Question about Jeep Grand Cherokee

5 Answers

ASD relay dosen't get ground signal from PCM. ASD relay has B+ and ignition +, ground wire from ASD socket to PCM is OK. When ASD circuit is jumped, PCM still has no 5v reference or communication to data link. PCM has ASD output acknowledgment when ASD is jumped. PCM has fused B+ and ignition + and both grounds. All diagnostics pointed to bad PCM. Got a used PCM and had it properly programmed right down to the VIN and mileage. Same results. I'm running out of options.

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  • 12 more comments 
  • skywaverick Jun 22, 2009

    There are well over 100 wires going to the PCM . I have already checked
    the 6 that are needed to get the PCM fired up. What other wires are you
    talking about?

  • skywaverick Jun 22, 2009

    I think I posted enough info on my problem to get specific response to resolve it. If not, please ask more questions, or suggest specific tests. I have everything Mitchell's and Alldata have to offer. I can't believe the second computer is also bad (the programmer would have said something)Is there something else not sending the correct info to the PCM that won't allow the computer to power up? Thanks

  • skywaverick Jun 22, 2009

    Actually, I'm not afraid of testing, I do it for a living. And if you
    reread what I have written, you'll see I've done more diagnostic trouble
    shooting than what the manufacture suggests or has available. It's just
    that in all the years I've rebuilt wiring harnesses and resolved
    electrical problems for other repair shops and dealers (that couldn't resolve
    the problem), I haven't encountered this particular problem. It is
    probably something like a sensor with a grounded reference voltage
    that's causing circuitry in the computer to malfunction. I was hoping
    some of you reading this might have encountered the same scenario and
    point me the shortcut. Sorry if I was representing myself as someone
    looking for the "right fuse", that "better be careful".

  • skywaverick Jun 23, 2009

    You mean "TWO" bad EPROMs? Because as soon as I hooked up the battery
    after changing the PCM there was no 5v reference or communication with
    my scanner. Not to mention, no ground to the ASD relay,etc. Do you have
    any ideas what could be making the EPROMs go bad as soon as I rehook
    the battery up after changing the PCM? Even a short to ground on the 5
    volt reference wouldn't fry the EPROM, it would take out the PCM's
    voltage regulator first, wouldn't it?

  • skywaverick Jun 23, 2009

    Yes, I'm familar with quad drivers for the injectors and such. I'll
    check the circuit for the ac including the polarity diode. I
    hadn't considered that circuit. It has to be something like that
    draging the PCM down. Thanks for the direction. I'll post my results.

  • skywaverick Jun 24, 2009

    I finally got a chance to ohm ALL wires going to the computer
    (disconnected from computer). The AC relay driver had 130 ohms to
    ground. The same as the relay coil. There was no wire that had less
    than 40 ohms to ground except for the 2 grounds and the brake sensor.
    (which was 1.7 ohms till pedal was pushed) I also checked PCI bus from
    PCM to BCM for continuity, 1.2 ohms. I also opened the computer and
    used test light (to load circuit confirming current capability) to
    confirm power and grounds made it through the PCM connectors OK. Even
    checked power and ground circuits with test light and volt meter
    simultaneously while cranking engine. Never dropped below 11.9 volts
    during crank. (10 volts is acceptable for computer function) Did I
    mention this vehicle has been to one dealer and two other repair
    shops. Lucky me!

  • skywaverick Jun 25, 2009

    When you write .002 ohms, do you realize you have your meter set to
    R-X1K is actually 2 ohms? A piece of brand new copper wire 6 inches
    long has MORE than two thousands of an ohm resistance.

  • skywaverick Jun 25, 2009

    Please.... if you don't want to read what's been done so far, don't waste time with redundant advise. i.e., if power (and grounds) have already been confirmed to the inside of the computer, what would checking the ignition switch accomplish? And how would I have done this without a schematic?

  • skywaverick Jun 25, 2009

    There are 4 wires that power up the PCM. 1 wire is battery + (hot all
    times), 1 wire is ignition + (hot run & start), and the other 2
    wires are ground to engine block. As previously written, all wires were
    tested from inside the PCM with about a 1 amp load while the engine was
    cranking. There is power and ground at the data link connector. My
    scanner (Snap-On 2500) powers up fine, no communication is the result.
    There is continuity on PCI bus and SCI trans & rec at DLC to PCM with no
    shorts to ground and .04 volts to power on the PCI. The .04 volts to
    power on the PCI wire at DLC appears to be inducted from the harness.
    When I jumper the ASD relay from 12 volt source to output side, it
    still won't power up fuel pump because fuel pump relay still needs
    signal from PCM to power relay. And just for S&G I jumped ASD &
    fuel pump relays at same time. But still no injector pulse. Both PCM's
    are "dead" . No outputs from either PCM's. I have others I need to work
    on for a while till I can get back to this one again.

  • skywaverick Jun 25, 2009

    I just looked at my schematics again. PCM connector C1 has ground pins
    31, & 32 (blk/wht&blk/tan, circuits Z11&Z12) going to right
    side of engine, G120. Are you looking at a Grand Cherokee or a
    Cherokee? My project is a Grand Cherokee Laredo. Both Mitchell's and
    Alldata show the grounds right side engine. Check your's again. Thanks
    for your input.

  • skywaverick Jun 25, 2009

    I suspected the voltage with no current capability when I did the 1 amp
    draw with the test light on the inside of the computer. I just looked
    at the wiring diagram and both power inputs to the PCM are fused at 10
    amps. I'm going to find a headlight or something that draws 9 amps and
    repeat the test on both grounds and power wires to the inside terminals
    of the computer while watching the voltage drop to prove the circuits
    ability to handle 9 amps of current. 1 amp test probably was not
    sufficient. Thanks for the idea upgrade.

  • skywaverick Jun 25, 2009

    I found a 100 watt xenon bulb that draws 8.3 amps and loaded both
    powers and grounds (one at a time) from inside the computer. All 4
    circuits handled 8.3 amps with no problem. Probably the last test I'll
    have time for before I take 1 week of vacation. Thanks to all that have
    helped, I'll catch you when I return. Rick

  • skywaverick Jun 25, 2009

    I checked the 3 power sources to the BCM- OK. I do believe there are
    some security issues because the SKIM light remains on during crank
    mode. The SKIM is supposed to back off the pulse with of the injectors
    to "0" if an invalid key is used. It is also supposed to disable the
    starter after 6 attempts. It never fails to crank and I don't see how
    it can control injectors with no power. I have temporarily wrote off
    SKIM functions figuring the light may be generated by PCM problems. This
    Jeep came from an auction running, then died at the dealers. I'm not
    even sure it has a security system. The BCM must be communicating with
    the instrument panel because the odometer and warning lights (all but
    check engine) work. But no BCM communication at the DLC.

  • skywaverick Jul 06, 2009

    Well I'm back from vaca and did some more diagnostics on the Grand
    Cherokee. As it stands now, I have confirmed power and grounds at the
    PCM. Still no outputs. SCI and PCI from PCM to Data link are good with
    no shorts to ground or power. When I hook up my Snap-On scanner to the
    data link, I have no communication with PCM. However, I have
    communication with ABS module and BCM. BCM tells me it doesn't have
    communication with PCM. This Cherokee has SKIS on the key but does not
    have VTSS. During "bulb-check" mode right after key is turned to run
    position, the SKIS light illuminates for 3 seconds then goes out for 1
    second, then comes back on and stays on. This indicates SKIS has a
    malfunction. This is expected with a nonfunctional PCM not accepting the
    key code. This condition would cause my no-start condition, but not
    the total shut down of the PCM with no communication. I have checked
    all the outputs of the PCM one at a time for shorts to ground. The only
    low resistance to grounds are ones that go to a relay or solenoid and
    are between 44 ohms to 150 ohms. Definitely not low enough to shut down
    PCM. Any more suggestions?

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5 Answers

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  • Master
  • 1,011 Answers

You say two wires have power and the other two would go (one is ground from computer the other to the fuel pump ect after the relay is grounded.When you jumped the relay did the jeep start or have fuel pressure .The no voltage to the obd2 connecter does not get it from the asd relay i am sure you checked all the fuses and fuse lnks correct.Worse comes to worse run a ground wire from the ground point on the asd relay wire that goes to the ecm. the relay still will not be activated with out the key on BUT please recheck all the fuse links..

Posted on Jun 25, 2009

  • 4 more comments 
  • mike loshbough
    mike loshbough Jun 25, 2009

    The 2 ground wires are not to the engine block nor should they be .the one is ground received by your pcm the other is to you fuel pump crank sensor ect.

  • mike loshbough
    mike loshbough Jun 25, 2009

    I just read the schematic so rethink your grounds!

  • mike loshbough
    mike loshbough Jun 25, 2009

    somewhere you have to have voltage but no or very little amps. like there is a frayed wire or bad fuse link.Was this jeep towed in this way?because you cant have 2 bad pcms right now it is brain dead either no proper power ,or a bad ground, fuse link, blown fuse ,.way to much corrosion on the battery terminal

  • mike loshbough
    mike loshbough Jun 25, 2009

    I also work at a shop but today i am off work so tomorrow i will check more into this.This would be a fun problem to solve if i was there.It is harder over the net for sure.So i will try to get back to you later Have you looked into the bcm for related issues like security system?

  • mike loshbough
    mike loshbough Jun 25, 2009

    The starter will still engage on all jeeps and Chrysler's but not on gm's.

  • mike loshbough
    mike loshbough Jul 06, 2009

    Wow you sure covered all your bases .this sounds like a job for a electrical shop that specializes in electrical wiring.I once had a eagle talon give me fits about the same problem so i replaced it with a used one to no avail then fried my brain and still came up with the same solution .Then i put a new computer in and it fixed it.I know you dont want to spend money were you dont need to but you sure know what your talking about so maybe dont double guess your self .I wish i could be there to help in person but you know i cant sure sounds just like a computer sorry cant help from here anymore:(
    good luck
    mike

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  • Master
  • 508 Answers

Ignition switch or major wiring issue get schematic and trace out!!!!

Posted on Jun 25, 2009

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  • Master
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You have a bad eprom ok?

Posted on Jun 23, 2009

  • 3 more comments 
  • Bruce Hathcock Jun 23, 2009

    have you ever heard of quad drivers and one connected tothe AC? have you checked it for .002 ohms tolarence and the ECM's .002 ground?

  • Bruce Hathcock Jun 23, 2009

    For the quad driver you will want to check the grounds, and I know this from experince, I used two $900.00 fuses to find out that a bad quad driver wa s at faultt he qauds would burn out as soon as the AC was turned on, it was one of those weeks I went hungry, But it was not even listed in any manual, I had to figure out whta was blowing the computer on my own, the hot line to the dealer didn't have a clue, later on they decided that maybe the mechanic needed to know about those things, at $900.00 a pop that made a difference. Good luck,

  • Bruce Hathcock Jun 23, 2009

    Be sure all grounds have less than .002 ohms Resistance on the computer the battery cables the frame to battery cable the obd II plug ground the computer housing ground and are yo wearing s ground strap? just asking, and if you are buying rebuilt that to could cause the problem. check voltage to the ep rom load it with a 1.5 ohms resister and read the voltage after the resistor, check the starter ground and the positive leads to the starter as well.

  • Bruce Hathcock Jun 24, 2009

    if you are reading fore the .002 ohms off any decive yo have to fix that problem, remember not more than .002 ohms.

  • Bruce Hathcock Jun 25, 2009

    do me a favor would you e-mail me so we can fix this we are both missing something and I don't give up, I need your diagrams so I can look for a circuit I suspetthere is one in the das but can't remember, and I don't have the alldata info in front of me, my e-mail is b123153h@yahoo.com put down asd relay IN SUBJECT LINE AND i WILL HELP YOU GET THIS FIXED.

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  • Master
  • 3,866 Answers

This what I would do and i am not sure you will like this suggestion, Run a probe on the secound board or computer witch the other tech suggested. You said your not getting ground the ground wire is either bad or the circuit is bad, If your not a car eletrician as we are I would leave it to the experts physically as this DIY repair can get hairy your playing with a car's computer and PCM componets here. Try running your own ground out to the battery if that dont work probethe secound pcb it will not hurt. But if your just thinking its not it and do not want to take that suggestion that is up to you this will never get resolved if your not willing to see, We are not guessing here we are ruling out what you already tried!!

When in doubt please take it to a eletrician if you think our suggestions are just no there for you that would be your best bet!


Rulds2008



Btw, I’m available to help over the phone in case u need at https://www.6ya.com/expert/edwy_1a56970cf1ea4620

Posted on Jun 22, 2009

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  • Master
  • 520 Answers

With computer disconnected I would try to ohm out all connections to check for faulty wire or connector. Also check for corrosion on the back side of relay bank.

Posted on Jun 22, 2009

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1 Answer

1991 Dodge Dakota 2.5 liter 4 cyc blew fuse I replaced fuse no start have replaced pick up coil ,coil,plugs ,wires, cap,rotor,fues all good still no spark and no start helllppppp please!!!!!


Make sure battery has a full charge. Did you check primary voltage to ignition coil, engine cranking, dark green wire with orange tracer? Use a test light, is it hot? The voltage comes from asd relay, check voltage and ground circuits. The load side of relay is that line with arrowhead, that circuit is fuse protected and hot all the time. The control side of relay is the left side in diagram, has to have voltage and ground. The voltage appears to come from ignition switch on or cranking. Grounded by computer.
The distributor has a sensor in it that sends rpm signal to computer, w/o that signal the computer won't ground the asd relay and you get nothing. The asd relay sends voltage to several systems. Just my opinion. Any applicable trouble codes?
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2001 dodge neon 2.0 se what should the ohm reading be between asd relay ground to the computer ground wires?


You don't do an ohm check . Hook a test light to battery positive an have someone crank the engine over an touch the point part of test light to the PCM circuit at the relay socket . If the test light light's the PCM is grounding the circuit . Watch this video ! Fuel Pump Electrical Circuits Description and Operation ASD relay chrysler

Oct 28, 2016 | 2001 Dodge Neon

1 Answer

Auto shut down fuse blows when I start the truck?


This information is straight out of the 1997 Breeze/Stratus/Cirrus Factory Service Manual (Yes I paid the $90 for it years ago)

__________________________________________________ _______________

Automatic Shutdown (ASD) sense - PCM Input

The ASD sense circuit informs the PCM when the ASD relay energizes. A 12 volt signal at this input indicated to the PCM that the ASD has been activated. This input is used only to sense that the ASD relay is energized.
When energized, the ASD relay supplies battery voltage to the fuel injectors, ignition coils, and the heating element in each oxygen sensor. If the PCM does not receive 12 volts from this input after grounding the ASD reley, it sets a Diagnostic Trouble Code (DTC).

Automatic Shutdown Relay - PCM Output

The PCM operates the Automatic Shutdown (ASD) relay and fuel pump relay through one ground path. The PCM operates them by switching the ground path for the solenoid side of the realys on and off. Both realys turn on and off at the same time.
The ASD relay connects battery voltage to the fuel injectors and ignition coil. The fuel pump relay connects battery voltage to the fuel pump.
A buss bar in the power distribution center (PDC) supplies voltage to the solenoid side and contact side of the relay. The ASD relay power circuit contains a 20 amp fuse between the buss bar in the PDC and teh relay. The fuse also protects the power circuit for the fuel pump relay and pump. The fuse is located in teh PDC.
The PCM controls the relay by switching the ground path for the solenoid side of the relay on and off. The PCM turns the ground path off when the ignition switch is in the Off position. When the ignition switch is in the On or Crank position, the PCM monitors the crankshaft position sensor and the camshaft position sensor signals to determine engine speed and ignition timing (coil dwell). If the PCM does not receive the crankshaft position sensor and camshaft position when the ignition switch is in teh Run position, it will de-energize teh ASD relay.
The ASD relay and fuel pump relay are located in the PDC near the battery. The inside top of the PCD cover has a label showing relay and fuse location.

ASD and Fuel Pump Relays

The following description of operation and tests apply only to the Automatic Shutdown (ASD) and fuel pump relays. The terminals on the bottom of each relay are numbered.

'------------------'
' __85 ___________'
' __87A '87 '30 ___' Sorry for the crudeness of this. This is supposed to
' __86 ___________' be the relay terminals!
'------------------'

OPERATION
- Terminal number 30 is connected to battery voltage. For both the ASD and fuel pump relays, terminal 30 is connected to battery voltage at all times.
- The PCM grounds the coil side of the relay through terminal number 85.
- Terminal number 86 supplies voltage to the coil side of the relay.
- When the PCM de-energizes the ASD and fuel pump relays, terminal number 87A connects to terminal 30. This is the Off position. In the off position, voltage is not supplied to the rest of the circuit. Terminal 87A is the center terminal on the relay.
- When the PCM energizes the ASD and fuel pump relays, terminal 87 connects to terminal 30. This is the On position. Terminal 87 supplies voltage to the rest of the curcuit.

TESTING
The following procedure applies to the ASD and fuel pump relays.
(1) Remove relay from connector before testing.
(2) With the relay removed from the vehicle, use an ohmmeter to check the resistance between terminals 85 and 86. The resistance shoud be 75±5 ohms.
(3) Connect the ohmmeter between terminals 30 and 87A. The ohmmeter should show continuity between terminals 30 and 87A.
(4) Connect the ohmmeter between between terminals 87 and 30. The ohmmeter should not show continuity at this time.
(5) Connect one end of a jumper wire (16 guage or smaller) to relay terminal 85. Connect the other end of the jumper wire to the ground side of a 12 volt power source.
(6) Connect on end of another jumper wire (16 guage or smaller) to the power side of the 12 volt power source. Do not attach the other end of the jumper wire to the relay at this time.

WARNING: DO NOT ALLOW OHMMETER TO CONTACT TERMINALS 85 OR 86 DURING THIS TEST.

(7) Attach the other end of the jumper wire to relay terminal 86. This activates the relay. The ohmmeter should now show continuity between relay terminals 87 and 30. The ohmmeter should not show continuity between relay terminals 87A and 30.
(8) Disconnect jumper wires.
(9) Replace the relay if it did not pass the continuity and resistance tests. If the relay passed the tests, is operates properly. Check the remainder of the ASD and fuel pump curcuits.

__________________________________________________ _______________

I know you said you replaced the relay, and this is a test procedure for the relay, but I have bought bad parts in the past. The description before the test procedure at least gives you an idea of what components are wired through and controlled by the relay. One of those may be faulty. Email me if you want or need wiring diagrams and I should be able to scan them and email them to you.

Jul 15, 2015 | 1992 Dodge Dakota

1 Answer

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are you sure that you changed the ASD relay? that code is for no signal from the ASD to the PCM. Check that you have constant 12v at the relay base and that you have switched voltage when the key is on at the relay base, then make sure you have continuity to ground at the relay base. If the relay clicks when the key is turned on then the internal coil is making and should be sending a signal to the PCM when the key is turned on.

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1 Answer

Asd relay has no power to the pcm and fuse panel inside has only half power run jumper wire to dead fuses and dash lights up and pcm powers up and jeep will start and run till jumper wire is removed


Hi, pull out the ASD relay and use a 12 volt test light to interrogate the relay socket. Hook your test light clip to ground and probe the terminals of the relay socket. There should be one hot terminal when the key is off and 2 hot terminals when the key is on. One of these is the power from fuse 6 and the other is from the ignition switch. If these are good, suspect the PCM is not turning on the ASD relay or the relay is bad. You can check for the ground signal from the PCM by moving your test light clip to battery positive and probing the other terminals in the relay socket. Again, one terminal should light the light when the key is off and both should light the light with the key on. If not, the PCM is not turning on the relay, and you should suspect your anti-theft system. Please let me know if you have questions, and thanks for using FixYa.

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Jun 05, 2011 | 2001 Jeep Grand Cherokee

2 Answers

My ASD fuse is making a clicking noise and vibrating. What is the function of this fuse?


ASD fuse is called an AUTOMATIC SHUT DOWN FUSE. The ASD sense circuit informs the PCM when the ASD relay energizes. A 12 volt signal at this input indicated to the PCM that the ASD has been activated. This input is used only to sense that the ASD relay is energized.
When energized, the ASD relay supplies battery voltage to the fuel injectors, ignition coils, and the heating element in each oxygen sensor. If the PCM does not receive 12 volts from this input after grounding the ASD reley, it sets a Diagnostic Trouble Code (DTC).

May 18, 2011 | Jeep Cherokee Cars & Trucks

3 Answers

I have a 02 grand caravan, there is fuse call asd that keeps on blowing.


Well in a short term, you have a short circuit somewhere. Here is a detailed toturial for you. Please rate this post, thank you.

Automatic Shutdown (ASD) sense - PCM Input

The ASD sense circuit informs the PCM when the ASD relay energizes. A 12 volt signal at this input indicated to the PCM that the ASD has been activated. This input is used only to sense that the ASD relay is energized.
When energized, the ASD relay supplies battery voltage to the fuel injectors, ignition coils, and the heating element in each oxygen sensor. If the PCM does not receive 12 volts from this input after grounding the ASD reley, it sets a Diagnostic Trouble Code (DTC).

Automatic Shutdown Relay - PCM Output

The PCM operates the Automatic Shutdown (ASD) relay and fuel pump relay through one ground path. The PCM operates them by switching the ground path for the solenoid side of the realys on and off. Both realys turn on and off at the same time.
The ASD relay connects battery voltage to the fuel injectors and ignition coil. The fuel pump relay connects battery voltage to the fuel pump.
A buss bar in the power distribution center (PDC) supplies voltage to the solenoid side and contact side of the relay. The ASD relay power circuit contains a 20 amp fuse between the buss bar in the PDC and teh relay. The fuse also protects the power circuit for the fuel pump relay and pump. The fuse is located in teh PDC.
The PCM controls the relay by switching the ground path for the solenoid side of the relay on and off. The PCM turns the ground path off when the ignition switch is in the Off position. When the ignition switch is in the On or Crank position, the PCM monitors the crankshaft position sensor and the camshaft position sensor signals to determine engine speed and ignition timing (coil dwell). If the PCM does not receive the crankshaft position sensor and camshaft position when the ignition switch is in teh Run position, it will de-energize teh ASD relay.
The ASD relay and fuel pump relay are located in the PDC near the battery. The inside top of the PCD cover has a label showing relay and fuse location.

ASD and Fuel Pump Relays

The following description of operation and tests apply only to the Automatic Shutdown (ASD) and fuel pump relays. The terminals on the bottom of each relay are numbered.

'------------------'
' __85 ___________'
' __87A '87 '30 ___' Sorry for the crudeness of this. This is supposed to
' __86 ___________' be the relay terminals!
'------------------'

OPERATION
- Terminal number 30 is connected to battery voltage. For both the ASD and fuel pump relays, terminal 30 is connected to battery voltage at all times.
- The PCM grounds the coil side of the relay through terminal number 85.
- Terminal number 86 supplies voltage to the coil side of the relay.
- When the PCM de-energizes the ASD and fuel pump relays, terminal number 87A connects to terminal 30. This is the Off position. In the off position, voltage is not supplied to the rest of the circuit. Terminal 87A is the center terminal on the relay.
- When the PCM energizes the ASD and fuel pump relays, terminal 87 connects to terminal 30. This is the On position. Terminal 87 supplies voltage to the rest of the curcuit.

TESTING
The following procedure applies to the ASD and fuel pump relays.
(1) Remove relay from connector before testing.
(2) With the relay removed from the vehicle, use an ohmmeter to check the resistance between terminals 85 and 86. The resistance shoud be 75±5 ohms.
(3) Connect the ohmmeter between terminals 30 and 87A. The ohmmeter should show continuity between terminals 30 and 87A.
(4) Connect the ohmmeter between between terminals 87 and 30. The ohmmeter should not show continuity at this time.
(5) Connect one end of a jumper wire (16 guage or smaller) to relay terminal 85. Connect the other end of the jumper wire to the ground side of a 12 volt power source.
(6) Connect on end of another jumper wire (16 guage or smaller) to the power side of the 12 volt power source. Do not attach the other end of the jumper wire to the relay at this time.

WARNING: DO NOT ALLOW OHMMETER TO CONTACT TERMINALS 85 OR 86 DURING THIS TEST.

(7) Attach the other end of the jumper wire to relay terminal 86. This activates the relay. The ohmmeter should now show continuity between relay terminals 87 and 30. The ohmmeter should not show continuity between relay terminals 87A and 30.
(8) Disconnect jumper wires.
(9) Replace the relay if it did not pass the continuity and resistance tests. If the relay passed the tests, is operates properly. Check the remainder of the ASD and fuel pump curcuits.

__________________________________________________ _______________

I know you said you replaced the relay, and this is a test procedure for the relay, but I have bought bad parts in the past. The description before the test procedure at least gives you an idea of what components are wired through and controlled by the relay. One of those may be faulty. Email me if you want or need wiring diagrams and I should be able to scan them and email them to you.

I hope this helps.

Please rate this post, thank you

Apr 07, 2011 | Dodge Grand Caravan Cars & Trucks

2 Answers

92 dodge ram 150 5.2 this truck has no spark no injector pulse has no 8 volt computr to rank sensor, no ground b/y wire to asd relay.


TRY UNPLUGGING DISTRIBUTOR PICKUP CONNECTOR AND SEE IF 8V SUPPLY RETURNS..IF NOT,TRY UNPLUGGING VEHICLE SPEED SENSOR IN TRANS..THESE SHARE THE 8V SUPPLY CIRCUIT TO CRANK SENSOR ONE OF THEM MAY BE SHORTED..THERE IS NO GROUND TO ASD RELAY BECAUSE THE PCM MUST SEE CAM AND CRANK SIGNALS TO GROUND THE ASD RELAY..I HOPE THIS HELPS

Aug 22, 2009 | Dodge Pickup Cars & Trucks

1 Answer

Engine won't start


Sounds like an AUTOMATIC SHUTDOWN (ASD) RELAY problem. Fairly common on the Caravan.
Heres a brief overview of the ASD.
The Powertrain Control Module (PCM) operates the Auto Shutdown (ASD) relay by switching the ground path on and off.
The ASD relay supplies battery voltage to the fuel injectors, electronic ignition coil and the heating elements in the oxygen sensors.
The PCM controls the relay by switching the ground path for the solenoid side of the relay on and off. The PCM turns the ground path off when the ignition switch is in the Off position unless the 02 Heater Monitor test is being run. Refer to On-Board Diagnostics. When the ignition switch is in the On or Crank position, the PCM monitors the crankshaft position sensor and camshaft position sensor signals to determine engine speed and ignition timing (coil dwell). If the PCM does not receive the crankshaft position sensor and camshaft position sensor signals when the ignition switch is in the Run position, it will de-energize the ASD relay.
The ASD relay is located in the Power Distribution Center (PDC). The PDC is located on the driver's side inner fender well Power Distribution Center . A label on the underside of the PDC cover identifies the relays and fuses in the PDC
Check for good ground.
Good luck...i hope this helps, please rate me a fixya.

Jun 25, 2009 | 1994 Dodge Caravan

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