QuestionQUESTION: 1999 plymouth grand voyager with 3.3L from cold start gives a good "service engine soon" bulb check then starts. During warm up, the engine idle gradually begins searching between 600-900 rpm. After engine is at operating temperature, the engine shuts down and the temperature gauge drops to lowest reading bottom of temperature scale with no "service engine soon light". After ignition cycle no "service engine soon light" bulb check or engine crank/start and the temperature gauge remains at low scale. During cool down the relays begin to chatter and after cool down everything is back to normal and is consistently duplicated. Grounds to pins 10 and 50 of the PCM read less than 1 ohm and no ground outs for pin 43 to sensors (hot or cold).
ANSWER: Hi Robert,
The best thing to do is get a fault code readout with a plug-in code reader. I believe the self-readout using the ignition key is not available in your '99 so check with a nationwide auto parts store (e.g. Autozone) to see whether they do that for free. Let me know the fault code number you get, if any. The relays chattering is usually a sign of a low voltage level on the battery so check what it is reading.
By the way, what is G-flex?
On the grounds, 10 and 50 are true chassis grounds for the pcm proper, and while 43 is shown to be a 'sensor ground' internal to the PCM, so I am not clear that pin 43 should show a ground when compared to the chassis itself.
Roland
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QUESTION: My code reader does not read any codes present. Pin 43 leads were only checked for not having a ground out, so those wires seem to be good. Battery voltage is 12.5v cold or hot and does provide a strong start(after the cool down). If the PCM is not a possibility, then load test of the battery would be nice to do if I could keep the battery warm long enough to get to the store. The battery is almost 4 years old, but it seems to be performing excellent, not ruled out though. BTW, the relays that do the chattering are the EATX and Engine Shutdown relays. As far a what G-flex is, that is the VIN code for the type fuel option for the engine.
AnswerHi Robert,
The PCM could be a possibility for that does play a role in the starter and the autoshutdown
relay. The etax is controlled by the TCM. The coolant temp sensor readout is operated by the digital data bus which is also involved in the PCM and TCM communications functions, So it is possible that the bus is shutting down in the fully warmed up situation, but most specifically the data bus of the PCM. I would think there would be a fault code. How sophisticated is your coder reader?
The loss of the 'check engine' light and the coolant temp gauge reading (assuming that the rest of the cluster works) suggests to me that the powertrain controller is failing when this happens. That controller is the input for both those via the PCM's PCI bus wire. So too would be the refusal to actuate the starter motor, and of course the initial shut down as the PCM warmed up.
So check fuse 16 in the power distribution box and the positive temp coefficient #1 in box under the dash when you are in the shut down mode, which are the power sources for the PCM. If those are conducting when you are shut down then I would believe that the PCM is faulty. It should show a fault code I would believe, when it has cooled down, but perhaps not under these circumstances.
Thanks for the ratings/nominations.
Roland
