GMC Repair: Distributor Ignition Module, gmc sonoma, wiring circuits

Question
1992 GMC Sonoma, 4.3 liter Z, hard to start, will not idle without foot on accelerator, runs very rough, trouble code 42. It WILL idle with EST in bypass mode, runs fine, smooth. I suspect Distributor Ignition Module/Control Unit. Is it a good idea to drive it with EST in bypass mode,or will cause further damage?

Answer
Possible faults are:

1. fault within the ECM (computer).

2. Faulty electrical connections from the ECM to the ignition module. connections.

2. fault in the ignition module.

You MUST test ALL of the wiring circuits BEFORE you go replacing electronic components such as the ECM or IGNITION MODULE. If any wire is SHORTED and you do NOT fix the short and simply plug in a new ignition module or ecm you will in most cases DESTROY the new ecm or ignition module.

If you simply install a new module and there is a short in the ECM you will DESTROY the new ignition module.

If you install a new ecm and there is a short in the ignition module you will DESTROY the new ecm.

If there is a short in ANY of the wiring you will also DESTROY the new ecm and or ignition module.


You MUST do the tets FIRST unless you are extremly LUCKY.



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