Now you see them, now you don't - another headlight issue

[tazwegion]

Last month the headlights seemed reluctant to turn on (but did within a few seconds), the vehicle gets mostly driven during the day and often by my partner who will sometimes provide feedback of any issues noted (getting better), she also reported unusual activity from the indicators and a tail light appeared to be blown... easy fix right?


On inspection today, all bulbs were active and operational albeit a little dusty as they have not required replacement for quite some time, during the test process the headlights suddenly failed to engage, a fuse right? wrong...

Fuses were check and the only one which was damaged was #18 which restored the rear cargo interior light, not all areas of the fuse panel had power when ignition was switched to the "Aux" position but all fuses tested AOK for continuity (with a circuit tester)


I understand that the switches can be a problem in many cases but the loading has been removed from this switch by a lighting relay modification including the use of circuit breakers.

There are no park lights, no low beam nor activity from engaging the indicator stalk (for momentary passing high beam), the switch happily operate the interior light override, no buzzer or delay action has ever been noted on this vehicle in relation to the headlamps being left on.

Will have more time tomorrow and intend to remove the switch and check what power is going in and going out, it was probably due to be replaced anyway, lucky for me I am on holidays still


FWIW I did cruise the related threads in search but there appears to be quite a spectrum of symptoms

[Gildo]

My guess would be the switch, this is a known problem in older XJs.

[tazwegion]

Thanks for your response Gildo however unfortunately the plot thickens... the switch checked AOK on the work bench with the following observations

* continuity between the 12v input and headlight output (switch fully extended)

* the parking light fused input (all switch positions) & output

* interior lights to (switch) chassis ground.

* the fused parking light input and dash light output (including rheostat)


My next test will be to determine if power is arriving at the connector



EDIT: Well apparently after disassembling the lower dash for better access (highly recommended) there appears to be power to the switch, which leaves a minor/intermittent short or dead relays

[layback40]

Dont give up on the switch just yet. Your test is under a no load situation. When yo put plenty of amps through it, expect to see a breakdown.

[Gildo]

Originally Posted by layback40

Dont give up on the switch just yet. Your test is under a no load situation. When yo put plenty of amps through it, expect to see a breakdown.

Also check the condition of the connector on the switch loose/arced connectors on the plug can do this too, it usually heats up and melts parts of the plug or switch.
There's also plenty of other connections between the plug and the relays and lamps.

[junglejuice]

Sounds like a good time to do an upgrade.....

[tazwegion]

Originally Posted by Gildo

Also check the condition of the connector on the switch loose/arced connectors on the plug can do this too, it usually heats up and melts parts of the plug or switch.
There's also plenty of other connections between the plug and the relays and lamps.

Indeed that is what I thought also, I suspect a relay however after rechecking the tail lamps, wiring harness and connector for a short/wire fracture everything is now operating as it should, intermittent faults are the worst

Originally Posted by junglejuice

Sounds like a good time to do an upgrade.....

Exactly however...

Originally Posted by tazwegion

the loading has been removed from this switch by a lighting relay modification including the use of circuit breakers.