HELP needed, 1988 XJ6 (XJ40) ,
Left turn & break lights not working, I checked the bulbs, OK. I checked the fuses, OK. I removed the module and tested it on the right side, module OK.
I'm at a loss for what else to check, ........ any ideas would be appreciated 
Thanks, John.

Tri checking the connections and earthing, John.

 

 

OK. I switched the left & right lamp control module, both modules work ,(and will work without being grounded) both bulb holders work, I checked all fuses (not knowing what fuse is for what , covers missing). My next question what plug supplies the power to the module ? The large round one with 4 wires or the square one with like 12 wires ?

hi

I'd test at the connectors for 12v when each item is turned on

but as 2 items are not working I'd say its a earth problem, check the light cluster, the lamp holders, there usually a metal grid that the circuit, check you have a good earth to each lamp holder, this metal grid can break sometimes

here's a link to manual that might help http://wilfredfoto.nl/XJ6 Series III/manuals/XJ6 Service And Repair Manual (Haynes).pdf