My 2006 xkr developed a whole host of problems. It started with a shifter release solenoid stopped working. Following discussions on this forum I took a switch assembly apart and tested with Ohmmeter and microswitches worked. I re-soldered all points. I connected them back to the harness, and pushed them manually, but no change. Just opposite - Now I am getting warnings : Electrical fault, suspension fault, handbrake on. All fuses are OK. I am not sure whether I shorted some circuit, but now I do not have any power coming to switches. Where I should look. Is the body ECM fried? Some hints, please. Handbrake warning light gone, Electric/suspension fault is persistent. Problem cannot be in faulty brake light switch. It has for pins. One microswitch connects pins 1 and 4, the other one 2 and 3. When pedal is in the rest position 1x4 connected, 2 - 3 disconnected. When pedal is depressed 1- 4 disconnected, 2x3 connected. One brake switch wire feeds to adaptive suspension control module. I am afraid that module is damaged.

 

dneu,
It seems odd to get all these apparently unrelated issues together at the same time.
The usual forum response to such a scenario is to first consider the Battery condition.
The XK8 modules are 'voltage greedy' and sometimes, when Battery supply is low, they cannot perform a complete self check in time and throw up various warnings.
Check Battery voltage. I have found that anything under 12.2 volts needs re-charging and over 13.2 volts is healthy (so it's not a big window).

 

+1

MULTIPLE unrelated faults is most often ONE cause - partially discharged or failing battery.

Eliminate this first before concluding the "faults" are genuine.

Graham

 

Brand new battery - no change

 

I don’t trust a new battery to get the job done 100% of the time with this car. I don’t trust the 20 year old charging system to be up to the task at hand. It’s pushing current thru circuits that are not as conducive as they were when new. Voltage drop on these cars is a reality that one ignores at their own peril

the age of the wiring & circuits, coupled with the car’s electrical complexity have made me a believer in keeping the battery on a reliable tender whenever the car is not in use overnight or longer.

Besides, a quality battery tender will extend the life of any battery.

I use the Deltran Battery Tender +, others on the the forum have their favorite brand. Whichever one you choose, is probably not that important. But using one all the time is important, & has helped so many on the forum that it’s hard to ignore the benefits

The battery and charging system may have nothing to do with the OP’s issues, but it’s a good practice to be in the habit of keeping a new battery at its best. And using a tender can impact many of the chronic issues these cars face.

Z

 

Charging is fine, believe me - 14.5 V. I do not have power going to the brake switch. More problems - Windows drop down when door is opened, but do not go back and refuse "to learn" it (although while holding the switch I hear the click). I suspect the body processor module got. somehow shorted. The scanner reports "fault in communication with ECU".

 

Hey, did you manage to fix the issue ? I am having pretty much the same problem and BPM is my first guess atm. Thanks for reply!

 

I had similar issues with my older XK8.

Assuming you're eliminated the battery as the culprit, I would go back to square one.
Was the only original problem with the shifter solenoid? If so, I would try to get back to the scene of that crime. It's preferable to serial killing the windows and suspension, in addition to the shifter.
The first thing I would put in hand is a schematic.
Then, go back to the switch(es) you soldered. Could you have shorted something in the process? By re-examining your soldering work, can you get back to only having the problem with the shifter?
You need to address that problem, of course. Could the problem with the shifter be something as simple as a fuse or a relay?

To be honest with you, I tried replacing the BPM to solve my similar problem and that didn't work. Eventually, I crudely hacked the system and wired the shifter solenoid directly to the brake switch. Which now clicks every time I press on the brakes...This leads me to suspect a problem in the brake switch that I never identified. The cause of your problem may differ.

In short (pun intended), I've always solved XK8 electrical problems with the schematic and an volt- ohmmeter.

Perhaps the certified techs on the forum might have a more scientific, knowledgeable and certainly less time consuming approach to sleuthing weird electrical problems on the XK8.

However, problems with malfunctioning shifter solenoids have confounded Forum members for years on end. Sadly a definitive solution has yet to be found.

 

A previous owner was a real expert. The car developed hydraulic leak in tubed to a convertible lock. Instead of replacing them somebody cut tubes and pushed through rear wall a brake tubing and connected it to original tubing. Fortunately. it did not last long and I had to replace complete tubing. Doing that I discovered that the brake line cut through the main harness and severed some wires. After re-soldering and insulating them problem was gone.