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Mystery Engine Electronics Problem
1994 Laredo 4x4, 4.0L, 42RE Auto Trans, 165K; Original owner.
Engine stalls at speed or from idle, usually after it has warmed up. Tach goes to zero and check engine lamp flickers. (The flicker is much quicker than the flash seen when checking engine codes.) Engine can usually be restarted quickly--if the check engine lamp lights, the engine will start.
Engine codes = 12 & 55. Transmission codes = 11 & 55. The engine and transmission run great when they run.
I have read the threads describing similar problems and have heeded the advice you posted. I have replaced the PCM (due to other problems), TPS, IAC, CPS, and cap & rotor, so spark is good when there is spark. I have cleaned both ends of the ground wires and engine and body ground points. I inspected the engine harness and did not find any obvious chaffing or broken wires. Fuel pump pressure, fuel filter, and fuel supply have checked out OK. The ignition switch does not seem to cause this problem.
The check engine lamp flicker always accompanies the engine stall and, when the engine does stall, the check engine lamp goes out and remains off. When the check engine lamp flickers, the fuel pump and auto shutdown relays click on/off with the flicker. This can occur for up to 30 seconds when I turn the ignition off. When waiting for the check engine lamp to light during engine start, the transmission governor pressure solenoid valve sometimes "buzzes" for approximately 10 seconds. (The transmission fluid is full and relatively clean and does not seem to cause this problem.)
I'd appreciate any advice any of you can offer.
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09-19-2006, 07:09 PM
