How do I go about testing a ground wire for my ECU?

-Mark W.
'88 SC Camaro w/ 305 TBI

 

Use the DC-voltage setting on a digital Volt/ohm meter. Red lead goes to 12V source like the battery + ,
black lead goes to wire coming from ECM. If the wire is being grounded then you will read battery voltage on the meter.

ODB

 

I'm tired and maybe misunderstood your question a little.
Same method can be used to test for grounds to be used by the ECU.

 

A better method is to set a digital VOM to the lowest DC setting and probe the ground (while hooked up) with one and put the other probe on the best possible ground you can. If you read more than .02v than the ground is bad.

 

another appoach is to set your DVM to the lowest resistance setting and measure the resistance between a known good ground and the ground point on the ECU. Also check to see if there are any other grounds on the ECU. If so disconnect that ground and recheck the first test

 

Joel has it. It is called "voltage drop". You can have O.O resistance in a wire, but when you apply voltage, it can become open, like most poor grounds do. When you perform a voltage drop, the circuit is loaded, and you are measuring how much voltage is "bypassing" the ground through the multimeter. Really, .05V is the max. It If you are checking ECM grounds, put the ECM is diagnostic mode (jump pins A&B) to turn the cooling fans on, this helps load the circuit.

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[This message has been edited by GMTech (edited February 15, 2001).]

 

Does anyone know where these grounds terminate D1 D3 D10 & A12
Also A11 goes to MAF pin B then pin A grounds somewhere also.