1997 Jeep Laredo Jeep Grand Cherokee Stalling

Tiny
RITCHIE56
  • MEMBER
  • 1997 JEEP LAREDO
Engine Performance problem
1997 Jeep Laredo 6 cyl Two Wheel Drive Automatic 156K miles

I've read zillions of these forums where Jeeps are dying and stalling at random. Do not replace anything! Its the connectors on your PCM (located on the firewall behind the coolant resivior). Here is a test: Remove your coolant resivior and set it aside (the battery makes a good holder for it). Now start your engine (if you can). While it's ideling, wiggle each of the three PCM connectors, if the engine starts to sputter or stall - there's your problem.
Cure1: Remove the three plugs. Remove the three screws that hold the PCM to the firewall. Get a platemakers or typewritter eraser, the type you can sharpen in a pencil sharpener. Polish each pin on the PMC - without bending them. Next, get a high quality contact cleaner and give a SHORT spray into each of the three plugs. Plug them back in and pull them out several times to help clean the sockets in the plugs. Plug them in for the final time. Make sure they latch in place. Go go to ACE hardware or the like and get 6 each 24" tie straps. Ace sells them in pacakages of 10. Strap each plug to the PCM using 2 tie straps, vertically - one on each side of the harness bundle. Do this for all three plugs. Get them nice and snug. Clip off the remaining strap length. Mount back in engine and start it up. Should work like a charm. I'm sure you've replaced everything else by now, so you shouldn't have any more problems.

In my case, the socket pins in the plugs are worn out to where the tywrap solution no longer works. I'm currently looking into replacement pins. The connectors can come apart to be repaired. So far the closest pins I've found cost $10 EACH! *Ouch* Still Looking! Good Luck, hope that Helps

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Thursday, March 18th, 2010 AT 12:09 PM

4 Replies

Tiny
BEEF99
  • MEMBER
Thank you for your insight but before posting you may want to take into consideration that there is more than what you describe that creates stalling in the year model you talk about. In the Jeep's PMs they talk about a bad design on the 3 screws as the 3 screws they put in were too long on quiet a few models during those years and would create stalling too. The way to fix this problem is to go to your local hard ware store and replace them with slightly shorter screws. What was happening was the screws were too long and were grounding out the ECU and making the vehicle stall at random times.
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Friday, March 19th, 2010 AT 10:18 AM
Tiny
RITCHIE56
  • MEMBER
That's true too. That was the first thing I did. Actually, you don't even have to buy new screws, I just took some nippers and cut a few mm's off the end since its basically a sheet metal screw. That's good to mention - thanks!
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Friday, March 19th, 2010 AT 10:22 AM
Tiny
RITCHIE56
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So here's what I've done so far. I replaced all my PCM connections with AMP circular connectors, 3 each with 24-positions. I made pigtails and soldered them directly to the PCM pins. The other connector, I crimped new pins directly to the harness, replacing the OEM plugs. So far, no bucking, random stalling or backfiring.
Previously when it backfired, it blew my catalytic to bits and blew it into my muffler. So now my muffler is partially clogged. Also disconnected the downstream O2 sensor. It stalled twice today at a light (idle in gear) but started immediately. I suspect one of the two, or both aforementioned defects may be to blame. Tonight I'm building an O2 simulator (got off the net) using spare parts I have laying around. If I can trick the computer, then hopefully it will behave better. The muffler will have to wait till payday. If anyone is interested, I will send you a picture of the mod and a parts list and required tools. The connector conversion took me about 5 casual hours.
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Tuesday, April 6th, 2010 AT 12:33 PM
Tiny
J QUINN ESS
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Which 3 screws are you referring to? Can you send a picture?
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Tuesday, November 1st, 2016 AT 2:16 PM

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