My wife's taillights on her 98 stop working. My wife has been in North Carolina for a couple of months and will be returning next week. I been putting it off but I best get it fixed before she gets home and the s### hits the fan.

Both taillights are out, believe it happened at the same time. Back up, turn, and brake light work. Sidemarker lights are also out but I think it is unrelated but not positive.

For the taillights I have checked and there is no power to the taillight socket in the assembly. Checked the fuses at left and right healboard fuseboxes for the BPM and fuses are good. I read an old post that Jagtechohio responded to with similar problems and I'm leaning to a problem in the BPM. I have a 98 parts car that I can get parts from and thinking of switching BPMs.

For the sidemarker not working I checked the fuses and they are good but I was able to put a jump wire to the socket for the fuse and the right rear marker light came on. So it has to be a problem before the fuse box. I haven't traced it down yet.

Experiences and suggestions appreciated. Thanks.

 

For the side marker lights the black connector ( about a foot back ) with about 5 - 7 wires gets corroded and the bulbs in the sockets get out of contact as you can bend the wire ears on the bulb for better contact . This can throw off trouble shooting logic as can be intermittent and temperamental as you rattle around the system . You will see the side marker lights in the below print I colored in brown and the # 3 relay with # 21 / 5 amp fuse in the trunk fuse box . There was a size up change in sidemarker light fuses on the X300 series . The relay is before the fuse ( this corresponds with your jumper wire observations ) so I would swap relay # 3 with relay # 5 . The relay command ground comes out of the BCM as the pink wire . This is the brake stop light relay so you cant drive in the swapped configuration .

For tail lights you would be looking at the blue I colored wires on the print labeled running lights . Before you change the BCM ( PITA ) there are 4 -5 fuses to it :

# 3 / 15 amp RH heelboard

# 5 / 15 amp LH heelboard

# 7 / 15 amp LH heelboard

Ignition switch gives it a ground on the 2 other points 1 stopsign labeled and 2 stopsign labeled . You are looking at good continuity as you rotate key sequence on pin 1 to 5 and pin 3 to 5 , Look for some corrosion on the pins as I found some on mine . The connector can be lifted straight up from the mounting clip so you can orient it in your hand . Look for a good ground on the socket side of the connector only on socket 5



Editing

 

I have a good ground at switch. Good continuity at 1 to 5. Open between 3 to 5. I cleaned the pins before testing. Changed the BPM and no change.

Does it look like a new ignition switch?

 

Not the ignition switch. Just changed it and still no taillights.

Stumped!!!

 

As you twist the key through each of it's positions and you never see 3 to 5 close it is a bad switch out of stock . I don't think I labeled the pins wrong but double check my work . Pin 4 to 5 is the key in / key out switch for the cars shutdown sequence to the Security system . You will see this referenced at the top left side of the print ( edited ) .

 

How did you remove the switch from the column as you replaced it before ?

 

Pretty simple. The bottom column covers were already off so all I had to do was loosen the 2 screws and remove. I used a replacement from one of my part cars.

 

Disconnect the battery and remove BPM connector , put 12 volts on the marked blue sockets and observe running lights . Run key through and check for grounds at the yellow sockets . Hook battery up and check for power at the 3 green sockets with lights turned on . Use a load tester to check the 3 green sockets . If all passes then replace the BPM .

 

Thanks for the help. I working out of town during the week so I won't be able to work on it until next weekend. Told the wife to rent a car until I get it fixed.
I like your ideas and process on checking the wiring. Your highlighted diagrams are really easy to follow.
I already changed the BPM with one that came from my 98xj8 donor car. The numbers matched. There is still a possibility it is the BPM but unlikely the two would have the same problem.
This weekend I will follow your advice and see if I can't pinpoint where the problem lies.
Thanks again, Bob

 

Follow the red and blue circled wires on the ends of the connector for proper orientation as you have a connector veiw in hand . Put bread twisties on these 2 wires and it resolves the frustration of Am I looking at it right and the mental work of having to double check . A load tester can be made from a light bulb as they will have the same brightness as you test each of the 3 power / fuse sources , this will verify what you are suspecting on a " cat whisker " connection not bridging a required current somewhere in the fuse box

 

Wire harness in hinge of trunk? I had lights out in the rear. Found several wires broken in the trunk hinge harness.

 

Thanks Larney.
If you get a chance post a picture of the location.

Much appreciated, Bob

 

My wires were in the passenger side hinge of the trunk. See pics below.



See the wires with the cover off.



I had one brake and both license plate lights and trunk lights not working. All just
because of some broken wires. The opening and closing of the trunk for 15 years(at that
time) made the wires break.Fixed 2 years ago with no issues.

 

Thank you. I will check that out. It might not be the cause of my taillight problem. The taillights are not in the trunk lid. But it is a Jaguar, a problem here might cause a problem somewhere else.
Thanks again, Bob

 

Lady P.,
I put 12v to the blue and taillights came on, wiring good from connector to taillights. Got 12v+ to the green. Got continuity from yellow #15 to ground.
No continuity from #41 to ground. Traced that back to the ignition switch and I got continuity from there to the yellow #41.
I don't the the yellow #41 Is a ground. Is there another ground to check?
It might be the BPM but seems strange that I changed it with one from another 98xj8 with matching #s and it has the same issue. I have a 99xj8 that I can try it's BPM but I don't know if the numbers will match.

 

The ignition switch gets confusing as more then one pole at a time makes contact as you rotate the key though . This can scramble the brain as you think only one pole at a time .

In the different way of looking at the switch at some point as you rotate the key around you should see pin 1 to 5 close and make a low resistance close to 0 meter reading . Mine was higher then 0 and will be replacing the switch . There is only 1 ground for the ignition switch at pin 5 in which my connector pin 5 was corroded . Check that the pin 5 to ground is close to 0 . There are 3 poles in the switch controlling many things and this ground may be good enough for some things ( and they work ) but not good enough for the thing you are looking at .

The Body Processor Module has a case ground and can be easily missed but important in a module's functionality .

Any questions , just ask

 

I had those symptoms on my 98 XJ8 and it turned out to be a broken wire on the lighting stalk on the steering column. The wires flex when you move the stalk to use the turn signal or dim the lights. I was able to solder the wire back in place then used a wire tie to secure the wires so the connections did not flex.

 

When this happen to you were your headlights still working?

 

Yes, the headlights were still working. this may help http://jagrepair.com/images/AutoRepa...s%20Repair.pdf

 

Pull the electrical manual for your car: you will see that the light switch has a wire for headlights and one for taillights. You will need to remove the steering wheel, the bottom cover and then examine each post for a broken wire or solder. I found I needed three hands to resolder (medical suture clamps worked).