Z55 suspension air compressor not working

2011 GMC YUKON
124,000 MILES • 6.2L • V8 • 4WD • AUTOMATIC
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RANI HOPKINS
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Air compressor is new and still wont kick on when powering on car. Put a new level. compressor on last night and it still. Didn't kick in. when by passing the relay last night it leveled the back end but it will not work otherwise.
Jun 10, 2020 at 12:52 PM
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KASEKENNY
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I assume you jumped the relay from 30 to 87? Take a look at the wiring diagram. If so, what is the voltage with the engine running on pin 85?

Then install the relay and tell me the voltage on the light blue/white wire at the suspension control module which is on the left rear of the frame.

The way this works is power is supplied from the fuse to pin 85 on the relay and then when the compressor needs to kick on, the control module grounds this relay through pin 86. This then closes the relay and the compressor kicks on.

If there is no power coming from the relay to the control module on this wire then the module is most likely the issue assuming the relay is okay.

Let me know what you find. Thanks
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Jun 10, 2020 at 5:01 PM