Hazards stop working when heated screen is on!

[oneandtwo]

Strange one, my hazard lights / flasher relay stops working as soon as the rear heated screen is turned on. Turn the screen off and the hazards start working again. 
 

It doesn’t happen when either left or right indicators are turned on, just the hazards. 

 

Any ideas? I’m stumped as to why! Only thing I can think of is I have LED lights all round and the replacement aftermarket LED flasher relay.

[crwoody]

Assuming it's a Td5 Defender, there is a shared common earth point, K108, linked to both the rear heated screen relay and the hazard warning relay, it also provides the earth connections for the radio and ABS and a few other things.

K108 is mounted on the bulkhead right behind the coolant expansion bottle, worth a look there first.

 

[oneandtwo]

This may help someone in the future;

I took a look at this last night and realised that when the heated screen was on, the dash warning light for the hazards came on as well, and when hazards were on, the heated screen warning light also came on. Looking at the wiring diagram, the hazard warning light pin and the heated screen warning light pin are next to each other on one of the multi connectors to the dash panel (Td5); the fault turned out to be a badly done crimp from the factory which had been flattened where it crimps the insulation which had caused the terminal to gradually wear a tiny hole through the plastic multi plug connector causing an occasional short between the two warning lights.

[Mo Murphy]

Good find  !

Mo