1997 GC Laredo PCM?

KLUCKM

MEMBER
1997 JEEP GRAND CHEROKEE LAREDO

1997 Jeep GCL 4.0L automatic 4WD 140K. Very well maintained vehicle with all

service records.
After a basic tune up, Cap,Rotor,Wires,Plugs, oil change and filters the sensors started to fail. First the Idle Air Control Valve then Throttle Position Sensor then the Autoshutdown Relay and finally the Crank Position Sensor after it died at an intersection($225 tow home). Codes were cleared after each sensor replacement and no codes were being displayed.
The current symptons are: Engine cranks but will not start, No spark from coil, No check engine light in any key position or codes from my Jeep code scanner, Scanner can not link with PCM, A/C clutch engages when the key is turned to the on position. And open door chimes sound intermittently even when doors are closed.
I bench tested the coil, and Camshaft Position Sensor at both ends and results were normal.
When running properly this Jeep is a pleasure to drive. If anyone has any ideas I would sure welcome them

8 Replies

SERVICE WRITER

MECHANIC
9,123 POSTS

How is the fuel pressure, in spec?

Was this

answer

helpful?

Yes

Friday, August 17th, 2007 AT 7:44 AM

KLUCKM

MEMBER
4 POSTS

I don't remember off the top of my head what the fuel pressure was but I do know it was within spec. Could a fuel pressure problem cause those srtange symptoms. The fuel guage has always fluctuated unless the tank is more than half full.

SPONSORED LINKS

Was this

answer

helpful?

Yes

Friday, August 17th, 2007 AT 9:12 AM

SERVICE WRITER

MECHANIC
9,123 POSTS

I was just trying to see if no fuel pressure was an additional symptom. The thing was various symptoms, is sometimes folks want them all to be related. Not to say they aren't. It is better to ga after a particular symptom such as a no start, and keeping in mind the other symptoms in case they are part of the puzzle.

The scanner linking problem should be a bridge to cross as it may open up some doors. Have you checked the fuse for the dlc yet?

Was this

answer

helpful?

Yes

Friday, August 17th, 2007 AT 4:28 PM

KLUCKM

MEMBER
4 POSTS

First, let me thank you for your time and advise. Since I have pulled and checked every fuse and relay I could possibly find. I found only the Auto Shutdown relay to be faulty and replaced it. I don't know exactly which fuse the dlc is or it's exact location so I can't say that I absolutely checked it. I can only assume that I have.
A friend suggested that a faulty fuel pressure regulator may be the culprit. His reasoning being that if the regulator were to be faulty it would send the same signal to the PCM as if the vehicle was in an accident and shutdown power and fuel flow for safety reasons. Does that sound correct to you? Please don't make me drop my fuel tank !

Was this

answer

helpful?

Yes

Monday, August 27th, 2007 AT 7:32 AM

SERVICE WRITER

MECHANIC
9,123 POSTS

I wouldn't expect that regulator is a problem as the pressure is in spec. The regulator is a mechanical device that works by springs and a diapham. It comes as a module

I would still like to try to get a code check if possible.

The DLC fuse is a 20 amp that is in the junction box under the right side of the dash. Fuse # 7

It may end up being the pcm, but They aren't real common for going bad...and they are pricy.