Quick question about any interconnection between the cruise control system and the ABS/DSC system on a 2004 XJ8.

My wife's car has recently thrown a permanent SBS/DSC light and in hunting down the culprit my wife informed me that her cruise no longer works. Unfortunately she didn't tell me this the first time she noticed it so I don't know if it happened at about the same time or prior to the ABS problem.

Since my SDD program is acting up I've been having problems getting an accurate code scan but it occurred to me that since the ABS senses wheel speed it might also send signals to the cruise control unit.

Am I hallucinating or what?

 

You are correct. Your wheel speed sensors are the first port of call, check the reluctor rings also.

While you're checking, put the battery on charge just in case.

 

'DSC Unavailable' after starting is a common symptom of a battery getting 'a bit past it'.

 

My cruise control is also not working and after about 35 miles, I get DSC Unavailable and an Amber light. Waiting for my indie to check for codes on IDS but all I can see is P1000.

 

RD,

You really need the codes to narrow down the diagnosis. The suspects include the wheel speed sensors (contamination or failure), reluctor rings (contamination, looseness, damage), the sensor wiring harnesses (the rear ones have three electrical connectors in the circuits in addition to the connectors at the sensors and ABS module), and the ABS module itself (for years weak solder joints have plagued ABS modules made by Ate).

If your speedometer is working, then the right rear wheel speed sensor must be providing a plausible signal. That sensor provides the vehicle speed signal used by the ECM, TCM, IC, TC, DSC, ABS, ASM, CC, power steering rack, etc.

Cheers,

Don

 

as Don wrote -
(for years weak solder joints have plagued ABS modules made by Ate).

i know its a different module . but
maybe thats a clue , as the CC module warms up it may loose a vital contact with a soldered component . might be worth a look , but still wise to start with the codes anyhow .

 

Cheers Andy. I went for a spirited drive last night and after about 30 miles I get park brake fault and cruise not available which clears on restart. I found another guy in the UK with an STR that had exactly the same problem after his STR had been parked up for a while, and the problem didn't go away with a new battery and was only fixed with a new EPB module. Incidentally, mine also started after it was parked up for a few months when swapping supercharger and did not resolve with a new battery. Found a good cheap EPB module so will rule that out first.