Question1996 Chrysler T&C, LXi, 3.8L engine, 240000 miles, random engine shutdown.
Last summer (2013) my van's engine began to randomly shut down without evidence of any other problems. This shutdown is not preceded by any symptoms to suggest the engine is about to stall; one moment the engine is running smoothly and in the next instant it shuts down as if an ignition kill switch was activated. This is an intermittent problem, occurring several times per week, and at all speeds including idle (for example, when stopped at a red light.) After the shutdown, I typically leave the ignition switch in the "ON" position, shift into neutral, and restart the engine as the van continues to roll forward. The van restarts without trouble in 100% of these shut down cases. The problem seemed to disappear during last winter, but reappeared this summer at about the same random frequency as last summer. I suspect failing cam and/or crank shaft position sensors, or perhaps a failing automatic shut down relay. I jiggled/tapped these components while the engine was running to see if this action might cause engine shutdown, but the engine continued to run smoothly. I also checked the ES17 splice point where wiring for the cam/crank shaft position sensors is tied together. The tape surrounding the flexible plastic conduit showed noticeable abrasion at the point where it contacted the chassis, but there was no indication this friction point had worn through the plastic conduit to damage the wiring inside. In addition, I jiggled the ES17 splice point while the engine was running and no shutdown occurred. I ruled out a faulty fuel pump because this component was replaced about 2 years ago. I recently observed DTCs of 12, 15, 61, and 55 after the engine had been run with the resonator/air filter unattached from the intake manifold. The next day, I reattached the resonator/air filter to the intake manifold, started the engine, and allowed it to come up to normal operating temperature over 3 start/stop cycles. I then recorded DTCs of 12 and 55. I suspect the 12 occurred because the battery had discharged from excessive use of the van's interior lighting as I worked on door lock actuators throughout the course of the previous day. (I put a charger on the battery overnight in order to start/stop the engine prior to the second DTC readout as described above.) How can I identify the cause of this random, intermittent engine shutdown problem?
AnswerHi George,
Thanks for the detailed history. It appears that you have the wiring diagrams for the vehicle.
The first thing to check would be the ignition switch (A21) output and PTC 1. You could jump A6 (battery source, say from the hot side of fuse socket 7 or 8 in the junction box) to the down-stream side of PTC 1, after you start the engine and see whether that then solves the problem, Disconnect the jump when you shut down the vehicle. See whether that by-pass approach solves the problem. If so, then do the jump to the upstream side of PTC 1 do differentiate the switch from the PTC as the source of the problem.
The other item that can cause intermittent shutdown is the egr valve not closing to a dead stop when you slow down or accelerate as that leans out the mixture too much. So check the operation of the valve stem to be sure it is moving freely and shutting to a dead stop by means of slot in the valve stem. You can spray some WD-40 on the stem where it enters the valve body to improve the action.
It is also possible that MAP sensor (or its wiring) may be flakey but not so much as to set a code. An erroneous MAP reading can also cause a mixture issue that prevents idle, but not so severely as to set a fault code. Check the voltage on the MAP signal wire to test this hypothesis.
Those would be my ideas for shutdown with no codes.
Please read the PS (below) and respond to it.
Thanks,
Roland
