08 Yukon denali. Service suspension msg on the dash. I was told by a local shop my compressor was bad. So I replaced it. Not the problem. It doesnt cycle when the key is turned on. Both rear level sensors have been replaced a yr ago. If I jump the relay plug it will run. Anyone have this issue? Thanks
need more details...
do the rear shocks hold air? they should inflate and stay inflated for days or even weeks, they should also still be inflated after a drive and not cycling the key
there are other specific things the pump will do like release some pressure after sitting parked for a minute or so and it will also release some pressure just before it turns on to inflate the shock bladders. It should also kick on if you have the key on or engine running and add a good amount weight to the rear end.
also to be more specific the service suspension message usually comes on because of a shock sensor or maybe a ride height sensor, you might want to check all 4 corners on both.
a tech2 or other ""high end" scanner like a snap on, etc will give you the specific code that is triggering the error otherwise it's a guessing game, a run of the mill obd scanner will not read the code, the code is a bcm code.