Just to pile up on the recent slew of stuff not working the blinkers on my Disco decided to pretend dead whenever the car gets up to temp. I have no clue what the issue could be. The relays are fine b/c they work fine until they don't. The green arrows flash on the cluster, just somehow there is no juice going to the relays. (also happens when I press the emergency flashers). The fuse is good.

Any thoughts on what could be causing this?

 

Do you have a copy of the ETM? It looks like the stalk is supplying ground to the BCU which then supplies a signal to the cluster and then the fusebox/IDM. Since the cluster flashes I'd say you can rule out the BCU and if it happens on both sides at the same time them it's unlikely to be a bad relay. You can try swapping them out with a different set to be sure. After that it gets complicated. It looks to me like power is supplied to the relays through C0582-7 and when turn signals are called for the IDM supplies the ground to pull in the relay and send voltage to the lamps. I think the best way to check this is to test for intermittent ground on the output side of the IDM, which looks to be most easily done at Pin 85 of each relay. Unfortunately this sounds like a fusebox/IDM issue.

 

The lubricant in contacts gets harder at low temperatures and prevents conduction. If wiggling switches makes them work, that is the cause for intermittent behavior.

 

The blinker in the cluster would not function if this were the case.

 

@ahab Thank you for the explanation - i would have never figured this out on my own.

In a typical Disco fashion, it looks like a massive PIA to diagnose. seem it will take more time to figure out than to change the head gasket. I think they must have been getting some kickbacks from harness manufacturer - nothing better than to run six miles of wire to run a blinker.