I shut off my '95 Dodge Neon and walked away noticing that the engine control computer is making a slight whine noise that is sustained indefinately after shutting off the engine. If I turn the ignition on and off again then off stops. It does not seem to do the whine thing every time and me be dependent upon temperture.
I am wondering if anyone has ever noticed this whining "symptom" of improper shut down to the Dodge Chrysler PWM engine control modules, perhaps before a failure of the PWM module or other problems developing such as a dead battery.
My understanding of the operation of the PWM electronics is that it shuts itself off after ceasing engine operation when the ignition switch on state is set to off because it needs to store trouble codes etc. The PWM stores trouble history codes prior to shut down so it turns itself off when the storage to non-volitile memory is finshed. The '95 model is supposed to be non ODBII version when it comes to emmissions inspections stations, i.e. they do not show it on the list for using he ODB II connector to verify emmissions control operation for the last 30 engine operating cycles etc., and the '95 Neon OBD II PWM requires the Dyno-test exhaust gas analysis approach like the ODB I version PWM models from '94 and earlier... so it may not have all OBD II parameter monitoring and storage functions implemented as the '96 models do which do not need dyno emmissions testing. Apparently the '95 Neon PWM was a transiton year for the ODB II implementation but I have had a Snap On 2500 Scan Tool on it to show ovegen sensor operating parameters and injector pulse durations so its at least a partial implementation of OBD II.
QUESTION: Has anyone seen this whine thing before? Is it typical of the '95 PWM operation at times or is it unusual? Has anyone noticed this prior to a PWM module failure? Should I be looking for a used replacement PWM?
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