g37 parking brake for drl

Hey Guys

Got DRLs running through the fog lights for a U.S g37 car. I would like to activate the DRL only when parking brake is off like the Canadian cars are done. I've done all the wiring through the IPDM, so how can I get parking brake signal. I don't want to touch BCM or ECM, I don't think IPDM gets this signal. Do I've to physically run it from the parking brake switch on the parking brake and run it through the firewall ? If so can anyone guide me through a similar job done.

thanks very much

What year is your G37?Sylvain Rochon

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This is what I would do Sylvain Rochon

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Parking brakes typically output a (-) signal when engaged - therefore with the above diagram the fogs would only come on with the parking brake set. You're going to have to tap the parking brake inside the vehicle. I've never traced it out, but I would assume it runs to the BCM. What is your hesitation with messing with the BCM? It's really no different then the IPDM you've already messed with. They are both small electronic modules that control outputs based on both digital inputs and CAN bus data. Assuming you grabbed switched 12vdc at the IPDM I would run the (-) side of the DRL relay coil in to the passenger compartment (should be an OEM grommet high on the passenger side behind the battery) and towards the BCM that is in the passenger kick panel. Connect a 2nd relay across the parking brake signal at the BCM (again, assuming it is there) and wire the (-) feed from the underhood relay through pin 87A to ground. If you did not add a relay at the IPDM let me know how you hooked it up and I may be able to provide more detailed info. Kevin Pierson

"therefore with the above diagram the fogs would only come on with the parking brake set." No, the fog won't come "on" with the brake switch set because the relay breaks the circuit. When brake is set, it sends a "-" to 85 and with ignition "on" on 86, it breaks the contact when relay makes the connection between 87 and 30 thus keeping the fog lights off til the parking brake is un-set and the relay comes back to make the contact between 87a and 30 thus lighting up the fog lights... So I don't agree with Kevin's statement. Sorry Kevin...lol... Sylvain Rochon

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Sorry about that, I misread the little numbers!Kevin Pierson

Thanks Guys. Hello Kevin, I guess I should be thanking you as I got some help from a Infiniti G35 forum and KP Technologies had great deal of input on a posting there. Anyways, I'm bit reserved in touching the BCM, first it was ECM/BCM were recently replaced at a dealership because of their screw ups and secondly it sits behind the glove compartment I think.

The parking brake 'SWITCH' on the parking brake outputs a (+)'ve upon parking brake release (OFF), so all I've to do is run it from inside through a firewall opening to the engine bay. Alternate easier route would be opening up BCM.

I'm trying to design my DRL with parking brake release AND Light/Auto/Park are OFF. I'm guessing no need to touch 'Auto' pin in IPDM, if lights come on through AUTO then the Light pin will have power going through. One thing I'm not sure about is if the Lights are ON, then DRL should be off as per the below diagram. Is there any other component I can combine this logic of parking brake ON and light OFF and would this still retain the Fog original functionality?

I'm using SmartDraw trial version, sorry about their logo.

There are 2 problems that I see with that diagram. First, make sure that the park brake wire does not rest at 12v when the ignition switch is off because if you have forgotten to put your park brake on, you'll have a current draw of 150mA because your relay #1 will be constantly on. Second, the way that I see your diagram, you'll be using the car's ignition to turn on your fog lights which I wouldn't do if I would be in your place. I would simply find the fog relay, find it's ground wire and simply use a relay to disconnect the ground when the park break is "on". That would simplify the project and you wouldn't play in the IPDM and BCM.Sylvain Rochon

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The OEM foglight is integrated in to the IPDM. The IPDM is CAN based. There simply isn't an easy (non destructive)way of accessing the wiring to the fog light relay. You should see what is required to just interface the OEM fog light switch (it is part of a matrix style multiplexed system that needs to be decoded). Fun cars for sure! Kevin Pierson

stclaus37 wrote: Thanks Guys. Hello Kevin, I guess I should be thanking you as I got some help from a Infiniti G35 forum and KP Technologies had great deal of input on a posting there. Anyways, I'm bit reserved in touching the BCM, first it was ECM/BCM were recently replaced at a dealership because of their screw ups and secondly it sits behind the glove compartment I think. The parking brake 'SWITCH' on the parking brake outputs a (+)'ve upon parking brake release (OFF), so all I've to do is run it from inside through a firewall opening to the engine bay. Alternate easier route would be opening up BCM. I'm trying to design my DRL with parking brake release AND Light/Auto/Park are OFF. I'm guessing no need to touch 'Auto' pin in IPDM, if lights come on through AUTO then the Light pin will have power going through. One thing I'm not sure about is if the Lights are ON, then DRL should be off as per the below diagram. Is there any other component I can combine this logic of parking brake ON and light OFF and would this still retain the Fog original functionality?

You're more then welcome for the info I posted - I was kind of a pioneer in the fog light hacking and to this day I am still the only person that has came up with a reliable way to use the OEM fog light switch to turn the fog lights on and off independent of the the headlights. Unfortunately, your diagram won't work. Do not confuse 12vdc at rest with actual 12vdc power. The 12vdc signal on the wire with the parking brake is not applied is simply a pull up voltage - there is no current behind it. You will NOT be able to power a relay off of that 12vdc signal. The current comes from the (-) side of the parking brake switch (that goes to the combination meter, not the BCM). So, you'll have to trigger your relay off of the (-) when on parking brake signal. Use igniton power for (+) voltage on the coil and for power through the relay to your fog lights (make sure you fuse it around 10A). In order to get the system to work when the switch is only in the off position I would consider using the parking light bulb as a trigger. You could possible tie the (-) side of the underhood relay to a parking light (+) wire instead of directly to ground. When the parking lights are off they will rest at ground and should be able to provide enough current to switch the relay. As soon as you turn the parking lights on the ground will drop out and the underhood relay will no longer work! You would have to install a diode in the ignition feed towards the underhood relay. So this is how I would do it: Relay 1 (inside car): Pin 85: Parking Brake (-) at combination meter Pin 86: Ignition Power Pin 30: Ignition Power Pin 87A: Ignition Power to Relay 2 Pin 86 with diode stripe facing under hood relay Relay 2 (under hood): Pin 85: Parking light (+) Pin 86: Ignition Power from Relay 1 Pin 30: Fog light output to both OEM fog light (Cut wires going to IPDM) Pin 87: 10A fused supply from battery Pin 87A: One of the cut fog light wires going to IPDM If you don't cut the wire going to the IPDM you can backfeed voltage through the IPDM and create all sorts of problems. The two wires are common inside the IPDM so only one has to be hooked up - the other can be hooked up as well or just taped off. This should allow the fog light switch to still work as OEM, should disable the DRL if the switch is in any position other the "OFF" and should disable the DRL if the parking brake is pulled!Kevin Pierson