Question about 1992 Jaguar XJ6

1 Answer

No Power to Fuel pump

With the ignition off there is 12v at the input to the fuel pump relay (circuit diagram shows direct wiring from battery to relay). When the ignition is turned on the 12v goes away and the car will not run. Taking a wire directly from the battery positive terminal to the relay input, just as the car wiring should be, the engine runs fine. Could this be a bad connection beteen the batery and relay? Ignition off - no current draw - 12v, but with the ignition on and the pump providing a load the whole 12v is dropped across the bad connection?

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  • ggryder Mar 05, 2009

    Everything works fine when I run a seperate wire direct from the battery to the relay (which is how the cars wiring is supposed to be anyway). I think this proves that the relay and everything associated with it and everything downstream in the circuit is ok.



    Since its almost impossible to trace a wire under the dash board it would be really useful if someone could identify and provide the location of any connectors between the battery and the relay.

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  • Jaguar Master
  • 4,369 Answers

I would check the ground for the fuel pump relay that operates the switch side of the relay.
You should have 2 12v inputs to the relay. When the relay gets 12v input, it closes the relay switch on the heavy current side that sends 12v to the fuel pump.

A relay is needed because you don't want heavy current going through the switch.

Also, most cars only run the fuel pump for 2 seconds when the key is turned on because you don't want the fuel pump running without the car running. If you listen closely at the fuel tank, you should hear the pump run for 2 seconds when you turn the key to "ON"
When the key is turned to "START", the fuel pump should run continuously.
The engine computer tells the fuel pump to shut off if the engine rpms are zero.
So, I would check the switch side of the relay. Power amd ground.

Posted on Mar 01, 2009

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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

2 Answers

Could I run a electric fuel pump on my 1998 Cadillac deville?


if it did not have an electric fuel before then the installation of an electric pump is a relatively easy process. If you have an electric pump already fitted but it has failed then remove it and install the new pump in its place. Take care to check all wires, fuses and relays and any pressure sensors for correct operation. Remove and blank of the opening for any mechanical pump on the engine
For new installation select an easily accessible place under the vehicle that can be protected from flying rocks and road debris. Run a power wire (red colour) from the run side of the ignition switch to the relay ( to be fitted ) near the battery or in the engine bay. Run this wire through an inline fuse close to the ignition switch to protect the circuit. attach to a coil actuation terminal of the relay.( look at the base of the relay for terminal identification. Run a black wire from the other side of the coil actuation pin on the relay to earth. Normally the same bolt that mounts the relay. Run a red wire capable of carrying 20 amps directly from the battery terminal through an inline fuse ( close to the terminal) to a power pin on the relay. Run another red wire from the outlet power pin on the relay to the electric pump. . Run an earth wire from the pump to earth.
This is a basic electric circuit for the installation of the pump. If there is a requirement for a pressure regulator or pressure sensor to control the pressure or pump operation , that control wire will be connected in series into the wire from the ignition switch so that when the pressure is reached then it breaks the circuit to the relay from the ign. switch and the pump will stop operation until the circuit is again completed. When the ignition switch is off there will be no power for the pump

Oct 09, 2014 | 1998 Cadillac DeVille

1 Answer

Car wont start


My routine to check non-starting motors: (petrol/gas models)

  • Check immobilizer status
  • Check fuel supply -does it reach the fuel rail when starting. If not OK, check 12v supply to fuel pump when starting. If OK, fuel pump maybe dead.If not present, check fuel pump fuse and relay.
  • If fuel supply is OK, check spark ignition. If not OK, follow the supply circuit backwards to the ECM. Coils and/or ignition amplifier connector should have one 12v supply to it when ignition switch is on.
For Diesels with 'common rails' you can take same approach for fuel. No ignition testing possible. The diesel fuel pump still needs battery power. It will make some sound when IGN is on. If not, check ALL fuses and relays.

Jun 12, 2014 | 1998 Oldsmobile Intrigue

1 Answer

2003 olds alero crank no start, thought it was passlock. by passed this, it almost starts with either. cycle the key and pump works but no pressure after that.


Make sure you're getting power to the fuel pump after start up. GM cars provide power to the electric fuel pump via the starting circuit when cranking and switch to alternator/battery power via the fuse block and 12v relay with ignition on in run position. Check your fuse block (bad fuse; power not getting to part of fuse block) and fuel pump relay. Could also be plugged fuel filter, bad pump or ?. but not likely because you get fuel while cranking. Check for error codes in the engine control computer (GM OBDII) as well but that probably won't show anything. Good luck and good hunting. I had a similar problem with a Chev Astro. Turned out to be power not getting to one bank of the fuse block because of a burned junction terminal buried behind the battery under the hood. Get out the multimeter and start looking for failed electrical components or broken wires.

Jan 21, 2014 | Cars & Trucks

1 Answer

30amp auto shutdown fuse blows is it alternater


The ASD relay supplies battery voltage (12+ volts) to the fuel injectors and ignition coil(s). With certain emissions packages it also supplies 12-volts to the oxygen sensor heating elements. The Fuel Pump Relay is a separate relay controlled by the ASD relay input to the PCM. Fuse #12 (10amp) provides 12 volts to the coil side of both the relays and the ignition switch. Fuse #6 (30 amps) supplies 12 volts to the output side of the relay. Fuse #16 (15 amp) from the relay output to the Oxygen Sensors and Fuse #26 (15 amp) relay output to the PCM. Fuse #24 (20 amp) is Fuel pump relay output to fuel pump. Fuse #19 (10 amp) supplies 12 volts direct to the PCM.
look for burned or melted wires in the offending circuit.
sounds like you wiggled a wire while installing new relay.

Mar 06, 2013 | 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

1 Answer

Starter motor went out on 92 5.0 ho replaced it and new battery, now fuel pump does not work I get a 542 code checked fuel pump relay and inertia switch both good fuse good


  • Code 542 indicates one of the following conditions:

Engine Starts:

· Fuel Pump secondary circuit shorted to power

· Fuel pump relay contacts always closed

· Open in fuel pump monitor (FPM) circuit between ECU and connection to POWER TO PUMP circuit

· Heated Exhaust Gas Oxygen (HEGO) sensor shorted to power

· faulty ECU

Engine Does Not Start:

· Open inertia switch or inertia switch circuit

· Open in or between ECU and fuel pump (This includes open in fuel pump brushes/windings)

· faulty ground connection at fuel pump

The easiest way to check this circuit is to go to the fuel pump relay. If the relay clicks when the key is turned to the "RUN" position, then the inertia switch circuit is ok.

The Pink/Black wire starts from the fuel pump relay and goes two directions. One side goes back to the fuel pump. The other side is the fuel pump monitor circuit and goes to pin #8 at the ECU. This wire should only be hot for a second or two when the ignition is turned to the RUN position.

The fuel pump relay receives power on the Black/yellow wire. It comes from a fusible link at the power distribution center. This wire should be hot at all times.

If all the above is working as designed, them you probably have a bad fuel pump.

Feb 13, 2011 | 1992 Ford Thunderbird

3 Answers

I have no power to the fuel pump on my 1996 TBird. Where is the fuse for the fuel pump located.


Do this test first. With the drivers door opened in a nice quite area turn the ignition key to the ON position without starting the engine. You should hear the fuel pump operating for 5 seconds which is priming fuel to the engine. If not heard the engines oil pressure sensor is at fault. The third wire from this sensor links to the fuel pump to prime. When the engine reaches normal operation oil pressure range the computer shuts off that circuit and turns on the fuel pump relay for the pump to run. That relay stays on until you shut the engine off

Jun 19, 2010 | 1996 Ford Thunderbird LX

2 Answers

No power to fuel pump or fuel pump wiring harness...


try the electrical ignition switch on the steering wheel colum

May 27, 2009 | 1988 Ford F 150

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