Question about 1999 Jeep Grand Cherokee
99 Jeep grand Cherokee Laredo 4.0 straight 6 - The first issue I had with this vehichle was the water pump. replaced it and had no problems for a time. after that was fixed i began noticing the vehichle sounded odd when idling, i would hear a CLICK and the engine would sound like it was reving then it would slow and CLICK and rev and slow etc. etc. The engine then choked out one night in the drive thru of a restaurant while idling, after this the check engine light came on, i had it read and it said crank positioning sensor, i replaced and the jeep drove great for about an hour then started dieing when idling, check engine light came back with tons of codes, my mechanic replaced the spark plugs & ground the battery clamps so they would tighten better, again drove great for a few hours then began dieing at every stop light, starts perfectly every time and runs better when it's cold. Mechanic then thought it was the coil pack, he replaced this which changed nothing and ended up putting the old one back in, he says i must take it to a dealer as he feels it is an issue with the computer.........please help
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Posted on Jan 02, 2017
I Found that the outboard PCM cover screw was shorting out the circuit board.
Short story long: I have a 96 Grand Cherokee 4.0L, 125,000 miles. Several weeks ago, I started to have stalling issues. Hot or cold, dry or wet, first drive of the day or last, it didnt matter. The engine would cut out. It felt like it lost all electricals.
At the time it was showing an ASD relay code. Swapped the ASD and A/C relays. Same problem. I didnt have time to look at it, so I had the dealer go through it. After 2 days and $200, they called and said it was the ASD relay, and that they put in a new one, and its all good. Um, ok, maybe I missed something. Im a trusting soul, but lets see if this fixes it. The next day the problem was back. I went back to the dealer and they basically said, We dont know what it could be, good luck with that. Now my wife knows why I dont go to the dealer. By the way, the old relay tested good.
My turn. Being the methodical aircraft mechanic that I am, I grabbed a multi-meter, contact cleaner, and wiring diagrams. I cleaned connectors, ohmed out wires and sensors, checked for power and grounds. Everything checked good. By now, its showing ASD, crank sensor, and primary ignition codes. Then, with my wife trying to start it, I wiggled the connectors on the PCM. Every time I wiggled the gray C3 connector just right it would run. When I let go, it would die. So I took the connectors apart and tightened up the crimps (I dont recommend doing this without the proper extractors and crimper). Threw it back together and BAM! Same problem. Well, time to bite the bullet and check for bad solder joints on the PCM board. I took the cover off of the PCM and realized that looking through the potting compound is like looking through Guinness Stout. But, I put it back in and hooked it up. It started stronger than ever, and didnt even think about stalling. Yes! I figured that I finally got the connectors sorted out, so I left it over night to cool down. Got up the next morning and it started right up and wouldnt stall even when wiggling the connectors. So I put the cover back on, put the PCM back in, hooked up the connectors, and BAM! It wouldnt start! That was the point when my wife asked, Hows it going? And I, being the methodical aircraft mechanic that I am, said, what the ----? Thats when my wife turned around and went back into the house. While smoking a pack of cigarettes, I thought, Gee, it runs with the cover off, but not with it on. DUH, wonder what it could be? So I backed out the two screws that hold the cover on and BAM! It started right up. Then, while it was running, I tightened the outboard screw and sure enough, it died. Yes! Aircraft mechanics love it when they can make things stop working. I cut the screws (1/4 long, factory screws are 1/2 long Torx head) with a pair of wire cutters, and shes been running great ever since.
Posted on Oct 07, 2010
Check to see if the fuel pump is running after it shuts down...could be a relay or the pump itself (overheating internally) Checked the fuel filter yet? Some crank sensors need to be shimmed. If it's too close to the flywheel even though you recently changed it, if it's too close to the wheel it can fail again. May not be the case but worth checking over. Also check the ceramic resistor on the left fender near the master cylinder if you have one. That too can cause problems.
Posted on Dec 27, 2009
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