Hello,
I am working on my sons 1999 XJ8 and think I may have a problem with the body processor module as the AUTO Headlight feature does not work. I did swap mirrors and it did not fix the problem. (It is getting voltage to pin CA55-5 and the dimmer voltage to lin CA55-2 and has a ground connection) I am wondering if the module from my 2000 VDP would work in this car? The car in question is not a VDP and is also a 1999 model. Is there any problem with swapping these modules to see if it corrects the problem? Like will something go terribly wrong with the car if I do? Is there a chart somewhere that lists the differences between BPMs?
In the trunk module ID tag for the 1999 JX8 the number is: LNC2500CG/ The 2000 VDP number is LNC2500CH/046

Thanks much for any replies!

 

Did you measure that the mirror pulls the headlight control voltage to ground when you cover the mirror front and rear area?

 

Just started researching but some points before I have wrapped my head around it

The BPM has to have the correct software installed referencing a master label under the hood

1999 and 2000 was a period that some wiring changes were done in respect to the engine upgrade away from the AJ26 to the AJ27

There may have been other whole car body changes effecting the BPM and how it controls things

The sunlight sensor for the headlights may be independent of the sunlight sensor for the climate control module which is what they eventually did in later years

 

Genuine Control Modules-programmable For Jaguar Xj 1998 - 2003 (from 812317 To F59525) Classic | Jaguar Land Rover Classic Parts

 

A cleaner and bigger picture to work with

CA55 pin 5 should be a feeler voltage of B + value

This will be the same as FC15 pin 16 on page 122 of your 99 wiring guide

CA55 pin 3 should be a ground

CA55 pin 2 researching , your security lock control unit gets involved on this wire , have you unplugged it and tested the auto light feature ?

this can be seen on page 56 of your 99 wiring guide as the Yellow/ White wire at BT1 pin 5

It might involve a Hard Reset of the SLCM with some precautions that others with this model would know about

This would be before changing any parts

You can remove the reverse light bulbs and see if that makes a difference

 

WOW! There are some smart guys on this forum! I truly appreciate all the suggestions and will troubleshoot a bit more and let you all know how what I find! I think I'll start with the headlight control voltage and work forward from there....
I may not get to this task today as I have a number of more pressing items to take care of around here......according to the boss.....
Bye for now...

 

You are correct that there are some wiring differences in this 1999 XJ8 and my 2000 VDPs. That and the fact one is a VDP and a year newer informs me to NOT try and swap the units.... Thanks for the advice....

 

I have a body control module LNC2500CG/xxx sitting in my office if you need one.




edit: on mobile, trying to put correct part number in. I have correct one

 

Well that is super generous! I'll fool around with the other troubleshooting tips first and contact you if that is the problem. This group is great!

 

The last 3 digits of the VCATS (suffix) is the important part.

 

After checking some the wires on the mirror socket, the signal at pin CA55-5 does not change from any lighting selection; Off, On, dip, or AUTO. It is essentially zero volts. The reverse lights pin 2 does change from 13v to about 0 volts as the shifter is moved to reverse. On my 2000 VDP the pin voltage is zero when not in auto and goes to about 3V when auto is selected on the switch. I will check the wiring from the mirror to the light switch to make sure the connections are intact.

 

If i have continuity from the mirror to the switch and them to BPM, I may want to try that module so generously offered by Col Sandurz ...

 

Does control voltage go high when you disconnet mirror from the connector ?

 

No, Nothing happens. After looking at the car, when the switch is in the auto position, nothing happens to the lights. I's like they are turned off as no exterior lights are on. I will check the switch and connections before I go any further at this point. The control voltage pin has no continuity to either the battery supply or ground so something is not connected....
I will be putting this project on hold as I need to work on one of the 2000 VDPs which are the daily drivers for us. The 1999 is a bit of a project car at this point..
I inform the group when I get the 1999 sorted out.

I will be replacing the A-frame bushings and ball joints on the right side of my car...J3. Looks like a real job to me.....Best, Dave

 

Control voltage(sense voltage) is coming from the bcm. It is not straight tied to battery or ground. Mirror grounds the sense voltage to ground and from what the bcm knows to turn exterior lights on.

 

Never did get the auto headlights to work on the 99 XJ8. After spending a great deal of time fixing just about everything on the car, my grandson crashed it after about a month of driving. Hit a high curb, mashed the radiators and took out the front suspension, and finally stopped when it hit the front of the engine and broke it off. Car totaled...Parts car now, Will strip it and get it towed away soon...Thanks for all the advice! As always, this is a fantastic forum and I could not have kept my cars going without it....
Dave

 

I had one of those days when looking over my back and the street twerked and I did not , totaled including a lot of things

But it was an unworthy GM product and then as the Chevy commercial went " I switched to Jaguar " so a blessing