g37 parking brake for drl

Thanks Kevin and Sylvain.

Kevin, here's the diagram based on your reply.

What kind of diode can I use on pin 87a of Relay 1? Is parking lights(IPDM 91) enough to switch off DRL or should I also include Headlights(IPDM 83) as shown in the diagram ? could you please confirm the cut on the fog wire in IPDM.

thanks very much

The wire coming from the IPDM labeled fog 86 needs to be cut. The IPDM side of that wire is not used, the fog light side of that wire connects to pin 30 of the relay. The headlamp low 83 wire is not needed. The head lights can not be on without the parking lights, so the parking lights alone will monitor all conditions.Kevin Pierson

Fog pin 86 either connected as shown or capped off.

Hey Kevin Need your help again. I have an issue right now, my fog fuses keep blowing up with or without any sort of relay. As I mentioned before the bcm/ecm were replaced recently, I didn't have this issue before that. And the fogs were working fine when I picked it up from the dealership after the work was done. The fogs (or DRL) stopped working few days after I got it from the dealership. i figured it must be fuse, but whenever I change the fuse in IPDM it blows up right away and that was with the relay. So I took the relay out and connect fog wiring in IPDM as from the factory, still same issue. BTW, I do have some aftermarket lights connected to the fogs connection. But this has been the setup for more than a year. Any suggestions. thanks

The very first thing I would do is remove the aftermarket lights from the circuit and see if anything changes. The lights, themselves, may be OK on the circuit, but that would be the most likely place for a short / damaged wire. When you put the relay in the circuit the relay bypasses the OEM fuse and provides power directly from the battery. If the fuse is blowing as soon as you put it in it, with all lights turned off, it would indicate a short to ground between the output side of the fuse (which should be in the IPDM) and the input side of the fog light relay (which should also be in the IPDM). You can check this by measuring resistance to ground between the output side of the fuse and ground. I would also check the integrity of the OEM foglight relay - make sure that internal contacts are not shorted. If they are, that opens the door to much more wiring that could be damaged. If the aftermarket wiring for the added lights rubbed through and shorted to ground and then the OEM fog lights were turned on it is very possible that the internal contacts of the relay arced and stuck. So, to sum it up: 1. Check output of fuse to ground to verify short (should be <1ohm) 2. Remove all aftermarket wiring connections to OEM fog lights 3. Check output of fuse to ground to see if short still exists (factory fog lights should read around 8-50 ohms I would guess). If this fixes the problem you can then put a fuse back in and see if the fog lights stay on all the time (indicating a stuck internal contact on the fog light relay). If this doesn't fix the problem then the next thing to investigate would be the IPDM....Kevin Pierson

Thanks Kevin. Fog fuse blows up only when the fogs are switched on, i.e. when switched on as DRL using a relay, or when switched on just with Fog switch with no relay in connection. Other lights function fine, Auto, headlights, parking even when fog fuse is blown. "When you put the relay in the circuit the relay bypasses the OEM fuse and provides power directly from the battery. " With regards to the above statement, in my initial setup I was supplying power to the relay using a 12v 'wiper motor' power supply from IPDM and this worked fine but this blew the wiper motor fuse as well after the fog lights fuse was gone. I changed the setup to powering it from the battery using a 15A fuse, and when I made the connection this blew the 15A fuse. !!!

If the fuse only blows when you apply power to the circuit then the fault will have to lie in either the wiring between the IPDM and the lights or in a bulb itself. Sometimes when bulbs fail they short out. Throw your ohm meter on a fog light wire and see if you can determine where the short is (I would recommend starting with the bulbs then work backward through the wiring. As I told you already the OEM foglight relay has two outputs, although internally they are connected. It would be beneficial for troubleshooting to cut one of the fog light wires so you have two independent circuits - you can then ohm out both circuits and compare the results to each other.Kevin Pierson

thanks Kevin. I had to replace one of the fog bulbs twice before. Maybe there's a different related problem to this. But if it is a fog bulb and is dead, why would this cause a short?? Can you please elaborate on the OEM foglight relay, where should I look for?

Bulbs typically fail in the "open" position but I have seen them fail in the "closed" position. When the element blows it is possible that either end of the elements could end up touching. When you apply electricity to the bulb it will arc and weld itself together, thus causing a permanent short. The OEM foglight relay is in the IPDM. It sounds like the relay is working properly to me and that the problem is after the relay. I would check for corrosion and a loose fit in the socket that you have replaced multiple bulbs in - if there is a poor contact with the bulb it can cause bulb issues.Kevin Pierson

Will keep you posted. thanks very much, mucho appreciato.