I am posting this since there does not seem to be an easy resolution. We have a 2004 XJ8 VP in very nice condition with about 100,000 miles on it. The problem is that in cold weather, about 25 degrees or less, the car will not start. The starter motor will not engage, and codes of : gearbox fault, parking brake fault, ABS fault and DSC not available show when the codes are read. When the car becomes slightly warmer it will start and run perfectly. Now it is Sept, and there has been no problems since it is warm outside, however with cold weather around the corner I have to find a solution. My question to this group is; has anyone ever encountered this situation. I did call a couple of dealers and no one could recall such a problem - ideas would be appreciated. One friend who is alot more knowlegable on auto electronics thought it may be a module, there are many in this car. Since it is a cold weather problem, it cannot be really tested until maybe December. - Thank you
Further info: New battery, grounds have been checked

 

What was the code for the gearbox fault?

 

I am told that multiple unrelated faults are a sign of a low battery.
No matter if it's new, it also needs to be charged. With a charger.
Don't see what else could correlate starter motor with the other faults.

 

Hi, Thanks for the response. I should also note that the shifter will not leave park as well as not turn over. Regarding the battery, it is new and fully charged - I will have to check and see if the codes are still on the computer.

 

The symptoms strongly indicate a battery or mass problem, that would have been my first guess too. It should be measured again how the battery voltage behaves under load of i.e. headlamps and window heating, and when the starter engages.

If the causes mentioned can be ruled out, one of the remaining causes are the immobilizer. Unfortunately, it is a very complex system involving several control units. An error message should then appear on the display. I would try first to see if anything changes when the second key is used.

Fritz

 

Fritz, Thank you for responding, I originally tried both keys with no difference. I will have to re-read the codes, but I cannot do that until it is cold outside;
there are no codes at this time. I may have to re-post this in winter.
Art

 

It does sound like a battery problem. You could try putting an ice pack on top of the battery, leave it overnight and check the starting problem.
Cold batteries do not perform as well as warm ones, fully charged or not.
The other obscure source of multiple glitches is related to bad wiring earths beside the radiator. Not usually temperature sensitive but at that age of car worth checking out. There is also the main earth cable for the battery.

 

Thank you, I appreciate your response. I think that I am in limbo until it becomes cold outside again. At that time I will retrieve new codes and maybe be able to do some testing. - Art

 

Searching this forum just on "cold", there is plenty thrown up by "unfortunates", but in particular the 2nd hit was "DSC fault etc" (intermittent) and a discussion of Grounds (a known problem).

Whilst it is necessary to have a fault in order to fix one, things like diagnosing battery or ground faults aren't likely to be helped by reading spurious codes, are they?

For example, I had intermittent headlights. I changed the indicator/headlight stalk thanks to advice on this forum. All fixed at least at time of writing. How would a code help?

Call me a skeptic, but you wouldn't have a cold problem if your car was in a garage. If it's not in a garage, how did you charge it? No offence, I just think it's more likely battery or ground-point related or otherwise not necessarily a fault that codes will point to if they are secondary/spurious. Sometimes (speaking generally) electronic modules are tested with freezer cans or hot blowers to identify "bad joints", though I haven't seen that here. Connectors are always worth wiggling, again general electronics with no particular logic, though obviously a potential nightmare on this car.

Just my opinion. Retired computer technician who hates computers with a passion.

 

Yes, I agree with you, especially since my knowledge and methodalogy of problems is "old school". The reason codes were mentioned is that a few people had asked for the code numbers and I cannot provide them at this time.
I have been driving Jaguar cars for over 50 years and my 67 for 25 with points & condenser - never had a problem that I could not solve or repair.
You may be correct in that it is a simple wiring problem, but not the battery. Maybe a missed ground; possibly - The modern world of 2004!!