Kevin Baker

I generally know that electircal stuff is not supposed to be hot, but whats the deal with the DME relay?
I had one go out last week, and I'll be buying a spare soon, but are they supposed to get hot? What needs to be checked to fix the heat problem?

Tadi

Hot electronics normally indicate a short of some kind. I'm not sure how hot the DME Relay is supposed to be, but if one just went out you might have a short somewhere thats just going to destroy the new one when you put it in. I would check the car for a bad circuit before installing the new relay. Someone else correct me if I'm completely off base.

Bri Bro

Both of the relay outputs from the DME are fused so I doubt the problem is a short. I am guessing that the one you want to replace was getting hot. I would suggest you measure the resistance across the two relays (there are two relays inside the DME) on both the replacement and the original, the coils contacts are marked on the case. The relay might have a short in it's winding and is drawing more current and overheating.

Another way the DME relays can overheat is if the contacts get pitted and increase in resistance. A normal relay has a resistance when closed of less then 0.01 ohms. With 10 amps of current, to will generate only 0.1 watts of heat. If the contacts resistance increases to say 0.1 ohms, the power goes to 1 watt. This will make the case warm to the touch.

I have replaced mine and many other have also had problems with this part. I always keep a spare around just in case.

Bri Bro

Bump

Peckster

I replaced mine with the new one and kept the old, which was still working fine, as a spare. Five years from now, I'll rotate with a new one (if I remember or care).

MHT

if the relay is getting hot it means that too much current is flowing thru it. The heavyest load on that relay is the fuel pump, either the pump is going bad or something is restricting fuel flow and making the pump work too hard. Check fuel filter, in tank filter or any problems with feul lines.