Quote:
Originally Posted by ChevyTech
Check for corrosion at the ECM connectors.
Here are some tests you can do:
Test the reference voltage to the TPS, MAP or BARO sensor. This tests terminal 21 voltage. It should be 5 volts. 4 to 6 volts is considered acceptable.
With the O2 sensor unplugged, and the engine idling - Test the voltage on the purple ECM wire for the O2 sensor. I can’t remember the exact value but it should be around .4 to .6 volt.
Reply back with your results.
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When measured with a DVM between engine ground TPS reference voltage (circuit 416, Gray wire) should be 4.75 to 5.25 Vdc. At Idle, TPS signal (circuit 417, Dark Blue wire) back to ECM should be 0.20 to 0.95 Vdc, but typically 0.50 to 0.60 is considered a norm.
ECM supplies 450 mV bias voltage - this may be different were you place you ground lead. This value maybe as low as 320 mV.
//RF
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