Question about Jeep Cars & Trucks

1 Answer

Diagnois pcm failure

Engine died after loose wire shorted on AC bracket. Will not restart, but does crank over. Mechanic states short burnt out PCM; need new PCM. Mechanic could not explain what troubleshooting was done to validate PCM was bad. However, with new PCM, engine does start. My question - How is a failure of the PCM validated, as opposed to replacement that might have simply allowed whatever did fail to reset.

Posted by on

Ad

1 Answer

  • Level 3:

    An expert who has achieved level 3 by getting 1000 points

    Superstar:

    An expert that got 20 achievements.

    All-Star:

    An expert that got 10 achievements.

    MVP:

    An expert that got 5 achievements.

  • Jeep Master
  • 1,282 Answers

Mechanic would have checked for good input of crank and camshaft sensors and good output of spark and fuel injectors. If they saw good input but no output, that would be a sign of a fried PCM

Posted on Jul 29, 2017

Ad

6 Suggested Answers

6ya6ya
  • 2 Answers

SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

Hi,
a 6ya expert can help you resolve that issue over the phone in a minute or two.
best thing about this new service is that you are never placed on hold and get to talk to real repairmen in the US.
the service is completely free and covers almost anything you can think of (from cars to computers, handyman, and even drones).
click here to download the app (for users in the US for now) and get all the help you need.
goodluck!

Posted on Jan 02, 2017

Ad
emissionwiz
  • 76164 Answers

SOURCE: PCM unit

PCM is the standard automotive acronym for Powertrain Control Module, previously know as the ECM and ECU, in 1996 the term was standardized for the new OBD 2 emission control system.

Posted on Apr 29, 2009

seans46
  • 161 Answers

SOURCE: 1999 pcm problem

I am not sure I understand your problem but I assume the truck is not running , no power to pcm ect. I have had jeeps sent to me after thousands of dollars have been pured into them and still wouldnt start. Change the CRANK SENSOR. This will 99% of the time fix this problem. When you go to the part store just make sure to give them the correct info. it is located on top of the transmission bell housing and is held in by 1 bolt most of the time it is a 10mm bolt . it is sometimes a pain but its on the drivers side top of bell housing . look at the new one to get idea of what it is. follow wire harness and unplug then take bolt out and remove sometimes you have to twist and pull out. put the new one in put bolt back and plug in. if it has a piece of felt on the tip leave it on it will come off its self . jeeps have a lot of pcm problems but the crank sensor can fool even the best mechanics making it look like a pcm problem. I take it you have not changed pcm's. if you do it will have to go to dealer to be programed and flashed in order to stay running. but hpoefully you havent changed pcm yet and go ahead and change that crank sensor asap

Posted on May 24, 2009

  • 98 Answers

SOURCE: what is a pcm sensor

its the main computer in the car, powertrain control module

Posted on Aug 12, 2009

  • 743 Answers

SOURCE: Engine cranks but will not start. No link to PCM

Spray Ether in the air intake...if it doesn't start then, I would suspect the timing chain.

Posted on Oct 11, 2009

emissionwiz
  • 76164 Answers

SOURCE: check engine light on for approx 60,000 miles. now

yes change the fuel pump module which contains the sensor.

Posted on Dec 29, 2009

Add Your Answer

Uploading: 0%

my-video-file.mp4

Complete. Click "Add" to insert your video. Add

×

Loading...
Loading...

Related Questions:

1 Answer

2003 f-150 engine code po353


Hi I'm Peter, here is a link to codes and below is what it says. http://www.obd-codes.com/p0353




P0353 Ignition Coil C Primary/Secondary Circuit Malfunction
The COP (coil on plug) ignition system is what is used on most modern engines. There is an individual coil for each cylinder that is controlled by the PCM (powertrain control module).
It eliminates the need for spark plug wires by putting the coil right above the sparkplug. Two wires are dedicated to each coil. One is a battery feed usually from the power distribution center. The other wire is the coil driver circuit from the PCM. The PCM grounds/ungrounds this circuit to activate or deactivate the coil. The coil driver circuit is monitored by the PCM for faults If an open or a short is detected in the driver circuit for coil number 3, a P0353 may set. Also, depending on the vehicle, the PCM may also shut down the fuel injector to the cylinder also.
Symptoms Symptoms of a P0353 DTC may include:
  • MIL (Malfunction indicator lamp) illumination
  • Engine misfire may be present or intermittent
Causes Potential causes of a P0353 code include:
  • Short to voltage or ground on COP driver circuit
  • Open on COP driver circuit
  • Loose connection at coil or broken connector locks
  • Bad Coil (COP)
  • Faulty Powertrain Control Module
Possible Solutions Is the engine misfiring presently? If not, the problem is likely intermittent. Try wiggle testing the wiring at the #3 coil and along the wiring harness to the PCM. If manipulating the wiring causes the misfire to surface, repair the wiring problem. Check for poor connection at the coil connector. Verify the harness isn't misrouted or chafing on anything. Repair as necessary
If the engine is misfiring presently, stop the engine and disconnect the #3 coil wiring connector. Then start the engine and check for a driver signal to the #3 coil. Using a scope will give you a visual pattern to observe, but since most people don't have access to one there's an easier way. Use a Voltmeter in AC Hertz scale and see if there's a Hz reading of between 5 and 20 or so that indicates the driver is working. If there is a Hertz signal, then replace the #3 ignition coil. It's likely bad. If you don't detect any frequency signal from the PCM on the ignition coil driver circuit indicating the PCM is grounding/ungrounding the circuit (or there is no visible pattern on the scope if you have one) then leave the coil disconnected and check for DC voltage on the driver circuit at the ignition coil connector. If there is any significant voltage on that wire then there is a short to voltage somewhere. Find the short and repair it.
If there is no voltage on the driver circuit, then turn the ignition off. Disconnect the PCM connector and check the continuity of the driver between the PCM and the coil. If there is no continuity repair the open or short to ground in the circuit. If continuity is present, then check for resistance between ground and the ignition coil connector. There should be infinite resistance. If there isn't, repair the short to ground in the coil driver circuit
NOTE: If the ignition coil driver signal wire is not open or shorted to voltage or ground and there is no trigger signal to the coil then suspect a faulty PCM coil driver. Also keep in mind that if the PCM driver is at fault, there may be a wiring problem that caused the PCM failure. It's a good idea to do the above check after PCM replacement to verify there won't be a repeat failure. If you find that the engine isn't misfiring, the coil is being triggered properly but P0353 is continually being reset, there is the possibility that the PCM coil monitoring system may be faulty

Apr 19, 2014 | 1998 Isuzu Rodeo

1 Answer

Hey there I have a 2001 jeep grand Cherokee 4.7L the #8 individual ignition coil burns up with in 2 minutes. I did some testing and found that it is receiving full ground contact from the pcm/ecm even with...


The COP (coil on plug) ignition system is what is used on most modern engines. There is an individual coil for each cylinder that is controlled by the PCM (powertrain control module). It eliminates the need for spark plug wires by putting the coil right above the sparkplug. Two wires are dedicated to each coil. One is a battery feed usually from the power distribution center. The other wire is the coil driver circuit from the PCM. The PCM grounds/ungrounds this circuit to activate or deactivate the coil. The coil driver circuit is monitored by the PCM for faults If an open or a short is detected in the driver circuit for coil #8, a P0358 may set. Also, depending on the vehicle, the PCM may also shut down the fuel injector to the cylinder also. Symptoms Symptoms of a P0358 DTC may include: MIL (Malfunction indicator lamp) illumination Engine misfire may be present or intermittent Causes Potential causes of a P0358 code include: Short to voltage or ground on COP driver circuit Open on COP driver circuit Loose connection at coil or broken connector locks Bad Coil (COP) Faulty Powertrain Control Module Possible Solutions Is the engine misfiring presently? If not, the problem is likely intermittent. Try wiggle testing the wiring at the #8 coil and along the wiring harness to the PCM. If manipulating the wiring causes the misfire to surface, repair the wiring problem. Check for poor connection at the coil connector. Verify the harness isn't misrouted or chafing on anything. Repair as necessary If the engine is misfiring presently, stop the engine and disconnect the #8 coil wiring connector. Then start the engine and check for a driver signal to the #8 coil. Using a scope will give you a visual pattern to observe, but since most people don't have access to one there's an easier way. Use a Voltmeter in AC Hertz scale and see if there's a Hz reading of between 5 and 20 or so that indicates the driver is working. If there is a Hertz signal, then replace the #8 ignition coil. It's likely bad. If you don't detect any frequency signal from the PCM on the ignition coil driver circuit indicating the PCM is grounding/ungrounding the circuit (or there is no visible pattern on the scope if you have one) then leave the coil disconnected and check for DC voltage on the driver circuit at the ignition coil connector. If there is any significant voltage on that wire then there is a short to voltage somewhere. Find the short and repair it. If there is no voltage on the driver circuit, then turn the ignition off. Disconnect the PCM connector and check the continuity of the driver between the PCM and the coil. If there is no continuity repair the open or short to ground in the circuit. If continuity is present, then check for resistance between ground and the ignition coil connector. There should be infinite resistance. If there isn't, repair the short to ground in the coil driver circuit NOTE: If the ignition coil driver signal wire is not open or shorted to voltage or ground and there is no trigger signal to the coil then suspect a faulty PCM coil driver. Also keep in mind that if the PCM driver is at fault, there may be a wiring problem that caused the PCM failure. It's a good idea to do the above check after PCM replacement to verify there won't be a repeat failure. If you find that the engine isn't misfiring, the coil is being triggered properly but P0358 is continually being reset, there is the possibility that the PCM coil monitoring system may be faulty.

Nov 09, 2013 | Cars & Trucks

1 Answer

1995 dodge ram 1500 318 motor it wont get fire where is the logic module located


Under hood,passenger side mounted on the firewall,but ...
Could be something else ,crank sensor or cam,or ign.rotor ect.
The module like 3 hundred bucks.Try this ,turn the key
on-off-on-off-on( without out hitting the starter) the check
engine light should begin to flash.
Here is a code list,may narrow down the problem.
Diagnostic Trouble Code Descriptions and service hints. Fault Code DRB Display Code Description. Service hints. 11 No Crank reference signal at PCM No Distributor reference signal detected during engine cranking. Check the circuit between the distributor and PCM. 12 Battery Disconnect Direct Battery input to PCM disconnected within last 50 ignition key-on cycles. Normal if battery has been disconnected, otherwise check battery power and ground connections. 13** No change in MAP from start to run No difference seen between the engine MAP reading and the barometric (atmospheric) pressure reading at startup. Indicates a problem with the MAP sensor vacuum system. 14** MAP sensor voltage too low or too high MAP sensor voltage output is outside the acceptable range. 15** No Vehicle speed sensor signal No signal received from the vehicle speed sensor during road load operation. 17* Engine is cold too long Engine temperature too high or too low while traveling. Check coolant level, radiator cap, temperature sensor, and thermostat. 21** O2S Stays at center O2S shorted to voltage O2 sensor does not detect rich or lean condition, or O2 sensor input voltage too high. DRB will indicate which side with dual sensors. The O2 sensor signal should fluctuate under normal conditions. 22** ECT sensor voltage too high or too low Engine Coolant temperature sensor input out of normal range. Check engine temperature sensor. 23** Intake air temp sensor voltage too high or low Intake air manifold temperature sensor is out of range. Check sensor. 24** Throttle position sensor voltage too high or low TPS sensor is out of normal range. 25** Idle air control motor circuits A short is detected in one or more of the idle air motor circuits. 27* Injector # control circuit Injector number # output driver circuit does not respond to the control signal. Check the affected circuit. 31** EVAP Solenoid Circuit Short or open in the EVAP solenoid circuit. Check for loose, broken, or shorted wire in the charcoal canister purge solenoid wiring and connectors. 32** EGR Solenoid circuit Short or open in the EGR solenoid circuit. Check for loose, broken, or shorted wire in the EGR valve wiring and connectors. Possible air fuel ratio imbalance not detected during diagnosis. 33* AC clutch relay circuit Short or open in the AC clutch circuit. 34* Speed control circuit or speed control switch always low or high An open or short in the speed control vacuum or vent circuits. Speed control switch input above or below normal range. 35 Radiator Fan low speed relay circuit Open or short in the radiator fan relay wiring. 37** Torque converter clutch solenoid CKT or Trans temp sensor too high or low Open or short in CKT wiring or connectors. Voltage out of range at transmission temperature sensor input. See NOTE #1 below 41** Generator field not switching properly Open or short in the generator (alternator) field control (regulator) circuit. This indicates a problem with the charging circuit and the fault is set when the battery voltage from the ASD relay falls below 11.75 volts. Wiring, connectors, fuses, and the ASD relay should be checked. A shorted battery cell can also trigger this fault. 42* Auto shutdown relay circuit Open or short in the ASD relay wiring or connectors. 43** Ignition coil circuit # Open or short in number # coil circuit. Indicates that the ignition coil's peak primary circuit current is not achieved with the maximum dwell time. 44* Battery temp sensor volts out of range An open or short in the engine coolant temperature sensor circuit or a problem in the PCM's battery temperature circuit. 45* Trans OD solenoid circuit Transmission OD solenoid circuit failure. Open or short in the transmission overdrive solenoid circuit. 46** Charging system voltage too high Battery voltage sense input above target charging voltage during engine operation. Computer is indicating that the battery voltage is not being regulated. 47** Charging system voltage too low Battery voltage sense input above target charging voltage during engine operation. Also, no significant change in battery voltage was detected during a test of the generator output. 51** System lean L-Idle Adap at rich limit or lean R-Idle Adap at rich limit O2 sensor signal indicates lean air/fuel ratio during engine operation. The computer ran the mixture to the rich limit of programming, but the O2 sensor still indicated a lean condition. L or R indicate left or right side O2 sensor. Fuel pressure problems can lean the mixture and set this fault. 52** System rich L-Idle Adap at lean limit or rich R-Idle Adap at lean limit O2 sensor signal indicates rich air/fuel ratio during engine operation. The computer ran the mixture to the lean limit of programming, but the O2 sensor still indicated a rich condition. L or R indicate left or right side O2 sensor. Faulty ignition components, high or low fuel pressure, or leaking injectors can set this fault. 53* Internal PCM failure or PCM SPI comm failure An internal PCM failure or PCM communications failure has been detected. 54* No cam sync signal at PCM No fuel sync (camshaft signal) detected during engine crank. No camshaft position sensor signal was received from the distributor. Problem with the distributor synchronization circuit. 55 N/A End of message code. A DTC 55 is used to end all DTC messages. This code does not show on the DRB tool and indicates a completion of the stored codes on the Malfunction Indicator Lamp (check engine lamp). 62* PCM failure SRI miles not stored Unsuccessful attempt to update Service Reminder Indicator miles in the PCM EEPROM (memory). 63* PCM Failure EEPROM write denied Unsuccessful attempt to write and EEPROM location by the PCM. Controller failure, check the PCM. This code can be set when attempting an unauthorized reprogram of the PCM. 71** Aux 5V signal voltage low The auxiliary 5 volt supply output voltage is low. The 5 volt output signal is not reaching the required voltage level. 72** Catalytic Converter efficiency failure The catalytic converter is not converting emissions in the proper ratio.

Feb 22, 2013 | Cars & Trucks

1 Answer

P0327 knock sensor code 00reodo


The knock sensor detects engine detonation, allowing the powertrain control module (PCM) to ****** ignition control spark timing based on the knock sensor (KS) signal being received.

The knock sensor produces an AC signal so that under a no knock condition the signal on the KS circuit measures about .007 V AC. The signal amplitude and frequency are dependent upon the amount of knock being experienced.

If an engine knock can be heard, repair the engine mechanical problem first. If there is no apparent engine trouble, check the KS signal circuit for a poor terminal connection at the PCM. If a problem was found, replace the terminal.

Check the KS signal circuit between the PCM and the KS connector for an open, a short to voltage, or a short to ground.

You can measure the resistance of the knock sensor by connecting a digital volt meter (DVM)between the PCM connector and the engine block. It should read abot 100K ohms. If it doesn't, you should replace the knock sensor.

If the resistance is ok, then you can connect the DVM to monitor AC voltage between the PCM connector and engine ground. Make sure the engine is off and the PCM is disconnected. Tap on the engine lift bracket with a socket extension while observing the signal indicated on the DVM. If any signal is indicated on the DVM while tapping on the engine lift bracket, then the PCM needs replaced. If replaced, this unit needs to be reprogrammed.

Feb 24, 2011 | 2000 Isuzu Rodeo

2 Answers

I am having a problem with the car turning on and off constantly and when driving on the freeway when i hit the excel orator it looses power to the gas peddal and comes back over and over again. while on...


It sounds like you have a loose connection to you coil packs. The speed sensors actually could be causing the problem also. If they are shorting out and shorting out the ECU then the car would die. And if they are just momentarily shorting, then it would cause this exact problem. When the car dies going down the freeway does the speedometer jump or the transmission act up?

Nov 12, 2010 | 1993 Oldsmobile Cutlass Ciera

1 Answer

I have a 1992 dodge dakota and awhile back i blew the engine. well we rebuilt it having it plained down and everything...then one day i was driving it and it just died and wont start. Its getting gas and...


when you say it has gas are you sure fuel is being injected by the injectors?
if not sure get whats called a noid light, sold at all large auto parts chain stores.they are inexspensive.plug it in to an injector connector and have someone crank engine if it blinks then injector signal ok. the light will give a dim blink which is ok.
no blink check for a blown fuse/loose connector/short to ground from engine to computer.
other causes of no start would be;
timing chain slipped
plugged exaust [melted down cat converter]
low fuel pressure
a major sensor failure,map sensor/throttle position sensor/crank,cam sensor
pcm [computer] failure or wireing to it
ignition switch
low compression

Mar 30, 2010 | 1992 Dodge Dakota

1 Answer

2002 Hyundai Sante Fe 2.4L


a crank sensor is a magnetic pulse sensor that tells the pcm(computer) how fast the engine is running. it sends an ac voltage to the pcm and that tells the pcm how fast and at what rpm the engine is running. there are no moving parts to the crank sensor itself. it just sends a pulse but it may be shorted or grounded or open. shorted can be caused be heat or liquid infiltration and will cause the signal to be skewed. grounded or open had to do with the windings in the inside. grounded means it has a wire toughing ground on the engine and open means it has a broken wire either inside or in the harness. i don't know where it is on that vehicle.

May 07, 2009 | 2002 Hyundai Santa Fe

1 Answer

Trouble codes


Trouble Code: P0139
O2 (B1 S2) Slow Response
Trouble Code Conditions:Engine started; vehicle driven at 20-55 mph with the throttle open for 2 minutes; ECT at more than 158ºF (70C); catalytic converter temperature is more than 1112F (600C); and EVAP purge is active. O2 Sensor signal voltage switches less than 16 times from lean to rich within 20 seconds during monitoring, or will compare the state of change between the front and rear O2 Sensors and if the differences are greater than a calibrated amount, the DTC will set. 3 good trips are required to turn off the MIL.
Possible Causes:
  • Exhaust leak
  • O2 element is contaminated, deteriorated or it has failed
  • O2 signal circuit or return circuit has failed

Trouble Code: P0344
Camshaft Position Sensor Circuit Intermittent
Trouble Code Conditions:Engine cranking or running; system voltage over 10.5v. The PCM detected an intermittent loss of the CMP Sensor signal during the period of 2.5 complete engine revolutions. The failure counter must reach 20 before this code matures and a code is set.
Possible Causes:
  • Wiring harness fault
  • 5v supply circuit open or shorted to ground
  • Tone wheel/pulse ring is damaged or corroded
  • CMP Sensor has failed
  • CMP Sensor signal circuit is open, shorted to ground or battery voltage or 5v supply
  • CMP Sensor ground circuit is open
  • PCM has failed
  • Trouble Code: P0340
    No Camshaft Position Sensor Circuit Failure
    Trouble Code Conditions:Engine cranking or running, system voltage over 10v. The PCM detected CKP pulses without detecting any CMP Sensor pulses for 5 seconds or 2.5 engine revolutions.
    Possible Causes:
  • CMP Sensor connector is damaged, open or it is shorted
  • CMP Sensor signal circuit is open or shorted to ground or to battery voltage or 5v supply circuit
  • CMP Sensor 5v supply circuit is open or shorted to ground or to battery voltage
  • CMP Sensor ground circuit is open
  • CMP Sensor is damaged or has failed
  • CKP Sensor is damaged or has failed
  • PCM has failed
Good luck....

Nov 05, 2008 | 2005 Chrysler PT Cruiser

Not finding what you are looking for?
Cars & Trucks Logo

Related Topics:

27 people viewed this question

Ask a Question

Usually answered in minutes!

Top Jeep Experts

yadayada
yadayada

Level 3 Expert

76164 Answers

Colin Stickland
Colin Stickland

Level 3 Expert

22156 Answers

Kevin Daniels

Level 3 Expert

1455 Answers

Are you a Jeep Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides

Loading...