Rick's Free Auto Repair Advice

no start no crank no click – GM

How to diagnose a no start no click on GM vehicle.

If you have a late model GM vehicle and turn the key only to hear nothing, you’ll most likely think you have a dead battery—and you may. But a no start, no crank, no click condition can be far more involved than that. In the old days, power flowed through the ignition switch and down to the starter solenoid. Not anymore. The ignition switch now talks to the body control module (BCM) and it’s the BCM that initiates one of two relays. The second relay, the more important of the two, is controlled by the powertrain control module (PCM). And it only operates the starter relay after it’s satisfied that the correct key is in the ignition.

Obviously you must have a good battery and clean battery terminals. But then you must have two good fuses in the starting circuit, two good relays, several good fuses to the BCM, good fuses to the PCM, and good grounds all around.

GM wiring diagram, starter diagram, ignition switch wiring diagram

Click here to download a PDF of the GM starting system wiring diagram

Click on the image here to pull up a PDF of a typical GM starting system wiring diagram. Depending on the year, model and engine of your GM vehicle, your starting system may be less complicated or use only some of the components shown here. For example, earlier anti-theft systems didn’t communicate the same way with the PCM. The bottom line is you MUST get the wiring diagram for your particular vehicle. Don’t even think you can find a free one online, because even if you get one with the right model and year, a different engine can change the whole thing. So I highly recommend that you plunk down $12 for a 1-week subscription to eautorepair.net and download the correct diagram for your vehicle. Then test the proper fuses, relays, and ground connections. The diagrams will show you where to find all those components in your vehicle. Hey, your mechanic is gonna pull a diagram. Why not save yourself a huge diagnostic fee and test these things yourself?

If you’d like to see other starter wiring diagrams, read this article.

© 2012 Rick Muscoplat

Posted on by Rick Muscoplat


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