Quote Originally Posted by ticker52
I looked at the fuse box under the hood and the C5 and does not exist. Along with the C4, C6 and C7. All of these are listed on the diagram as the struts. I have no inputs for fuses in thos spots.
The A3 which is the PCM is a good fuse.
So, is there anything else to check?

I'll copy and paste what it says in my all-data for you...



Code I039 will set if the ignition is on and the IPC is not able to exchange data with the RSS module (if any other communication codes are stored along with I039, see the chart of "MULTIPLE INTERMITTENT CODES"). When this is the only communication code stored, the problem must be one of the following:

  • An open in CKT 800 between the Electronic Brake and Traction Control Module (EBTCM) and RSS module and an open in CKT 800 between the RSS module and programmer (ACP).
  • An open or short in the RSS module power or ground circuits.
  • A faulty RSS module.
During the time the failure is present, no RSS diagnostic information will be available for display. The "SERVICE RIDE CONTROL" message will be displayed on the IPC. Also, while in the service diagnostic mode, this code will remain active, always checking for proper operations.


C5 is the power supply to the RSS module in my car.... I would take a paper clip and jump the terminals on C5 to see if it works with that circuit closed.... By any chance, does your deville have the 4.9 liter engine rather than the northstar?


Quote Originally Posted by M.A.C
Thank you! I appreciate the help.

I'm going to follow-up on your advice. If it turns out there is an internal short to ground, I take it that the compressor must be replaced?
Yes, that's one fix for it (easy yet expensive). But it is possible to just fix the old one (hard yet cheap)... LOL, if you're like me you'd give it a shot. I try to fix everything. lol