1994 Jeep Grand Cherokee cranks but does not start.. - Page 2 - JeepForum.com
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post #16 of 25 Old 10-31-2011, 01:13 PM
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1995 FSJ Cherokee 
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Location: Okmulgee
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Here's a dumb question......what's a PCM?

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post #17 of 25 Old 10-31-2011, 02:08 PM
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Power control module it's the cars computer
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post #18 of 25 Old 10-31-2011, 02:09 PM
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Well in this case the jeeps computer
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post #19 of 25 Old 11-01-2011, 05:54 PM
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1993 ZJ 
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my security system was automatically turning on because i do not have a clicker and when i unlocked the car without it the security system automatically turned on and i couldnt start the car, my mechanic told me the way to disable it is to unlock and lock the passenger side door three times in a row
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post #20 of 25 Old 09-18-2012, 03:36 AM
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2008 KK Liberty 
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For others finding this thread, check the 5 volt reference signal to the cam or crank sensors on the harness. If it isn't there, the computer isn't alive. It may be a bad PCM or a blown fuse. But not seeing the Check Engine Light on the dash when the key is first turned on should have been a dead give away that the computer wasn't alive. Hope this helps out someone down the road.
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post #21 of 25 Old 10-12-2012, 01:21 AM
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Don't forget to check your neutral safety switch poor contact or broken filament in the position arm inside will create a dead short to the pcm. causing a no start no fire just crank and crank situation. On the 1993 zj you can open the casing of the switch and take them apart. check continuity through all wires in all positions and check continuity through the arm itself. There is a fine filament that runs through the arm. These burn out from jump starting other rigs ( don't do it) I priced one and the cost was $400 Not. I fix mine by cutting a Chanel in the arm and super gluing a slightly heavier wire making the connection stronger. Clean the striker plates and coat with a thin film of dielectric grease. Put it back together reinstall on trans. adjust per your repair manuals instructions. Seven years now with no problem from it. This should be one of the first things to check because that filament is extremely light gauge about as thick as a stand of hair and burns out easily.
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post #22 of 25 Old 11-14-2012, 09:00 PM
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1994 XJ Cherokee 
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I am having the same problems as well. my check engine light does come on however. i had originally taken the jeep to a local shop. they could not figure anything out for 3 days, then they took out the security module and bypassed it somehow (i have no idea what they did). That fix lasted 2 whole days. Next I replace the Crankshaft Position Sensor (worse job i have ever done on a vehicle!!). taht didnt work until i replaced the engine cutoff relay.
the car started and ran (very roughly) for 3 days in a row. i decided to take it for a spin.. it shut off like a lightswitch on a hill out of town. a $60 tow later i am reading this thread and decided to take out the PCM (as have a ton of electronics experience). the board is covered in one inch of a rubber like material!!!! Is this normal? Can this be taken off so one can work on the board? and per the last post, could a bad Neutral Safety Switch be the cause of all my problems?
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post #23 of 25 Old 11-16-2012, 10:39 AM
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1994 ZJ 
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As far as I know the Neutral Safety Switch (NSS) only keeps the starter from engaging.

Lon Allen - 94 ZJ Limited 5.2 327K miles and counting
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post #24 of 25 Old 11-24-2012, 09:02 AM
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1994 ZJ 
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Location: grand terrace
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94 Jeep ZJ No Sart after "DEATH WOBBLE" to a No Start Condition

Severe death wobble knocked out electronics. Read here about a lost CCD communication to the PCM. Is the CCD abbreviation "Chrysler Collision Detect"? If so can it be reset somehow? The wobble was so severe I thought I had lost a wheel at 60 mph. I have completely rebuilt the front suspension etc. Now have a "no spark condition". Have 12 volts to coil,but No Trigger pulse to fire it I have checked all connections to sensors and pulled pcm connection to clean and check pins.Alarm has been disabled by grounding purple/yellow wire. CEL displays only the 12 and 55 because battery was disconnected.
Cranks fine,swapped out asd and fuel pump relays.Verified fuel pressure etc.
Any ideas on the CCD translation?
During the first few Death wobble events, the jeep would stall as i pulled over to the shoulder. Jeep would crank only and not spark. In desperation I reset the factory alarm at the door lock and it fired right up.

have replaced the crank sensor,cam shaft sensor,Distributor cap,rotor and wires.
Have supply voltage to all sensors and when key is turned on the CEL appears for 3 seconds and Pcm goes through its diagnostics check and does go out. Have fuel pressure to spec. Have tried gas in the Throttle Body,no spark.
has not throw a DTC code since the original stall after DW. Currently shows the expected 12 & 55 codes.
Does anyone know if a failing Coolant temp sensor would cause a no spark condition???
Besides the dealership,does anyone know a shop that has the OBD1 diagnostics scanner to look at live data close to Colton,calif. area???
Any ideas are welcome!!!

Last edited by rmack2; 01-30-2013 at 01:17 PM. Reason: additional items added
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post #25 of 25 Old 08-21-2013, 03:22 AM
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Jeep retarded start

The main culprit is the CPS or fuel pump....if the security module and the PCM won't communicate, the fault most likely is the PCM...best to replace with a PCM without security...the VTSS may work anyway but not in conjunction with the PCM.....the security module is impossible to find, and if the PCM is faulty then replacing VTSS won't help......I have done this (replace PCM) and the Jeep (94 GC) works perfectly ...the PCM module cost was $159 including shipping... a bargain considering all the time spent and aggravation, shot-gunning parts like the CPS and other parts in the ignition...Have lots of spares now....I could get it to start by going to the security mode and setting off the alarm and then turning off with the fob....but this also failed in the end....I have 350,000 miles and still going...Doug
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1994 zj , grand cherokee , pcm , security

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