05 ESV Air Ride Compressor Not Running Even After Replacing

[BlueOvalKid]

2005 ESV Platinum

Air ride compressor was not running. To diagnose I looked at fuses and jumped relay pins and still wouldn't turn on.

Based on above I bought a replacement compressor from Arnott and replaced it along with rebuilding the dryer.

Put everything back in and the compressor is still not turning on.

Also, the STUD1 fuse, RTD fuse and IGN 3 fuse are all good.

Started looking at the relay:

Pin 30 has 12v with key OFF

Pin 85 has 12v with key ON

Jump either to pin 87 and the compressor turns on (obviously dependent on key position).

What feeds pin 86 to complete the relay circuit? I'm thinking it has to come from either the compressor or computer to signal the relay to close the bridge to pin 87.

Does anyone have a wiring schematic for this relay and what circuits control it?

Any other thoughts?

[Cadillac Jim]

Do you have a code reader?  The OBD codes will likely tell the tale.  If you have had a DIC message "Service Suspension" or some such, that means that there certainly is an OBD code waiting to tell us something.

 

Here is the schematic.  Note that there is a relay, which is always a good place to look.

 

 

 

 

Here is a picture of the relay.  It's on the body, not in a relay center.

 

 

[BlueOvalKid]

If I'm looking at the schematic correctly then pin 86 of the relay is controlled by the ESC computer, correct?

I have checked all other pins of the relay and they are working properly.

Since I don't have any DIC messages would this point to the ESC computer being bad then and I need to replace?

[Cadillac Jim]

I would try looking at the relay pins 85 and 86 and see if it has voltage, and, if it does, try grounding pin 86 to see if that does the trick. If it has voltage on pin 85 and doesn't turn on the compressor when you ground pin 86, I would replace the relay.