Weird electric issues....IPDM or BCM?

[stoopideric]

I am having an electrical issue that I can't figure out. My lights and wipers will randomly stop working. I can leave the negative cable off for a while and they will work but then they may go out when I'm driving but definitely won't work on the next start up.
There were a few pins corroded in the BCM, I cleaned those up and it had no effect. I saw in an FSM where if those fail the IPDM test to check the ground for that circuit but I am not sure where that ground point is at. It is only those 2 things that do this, everything else works fine.

[VStar650CL]

You need to be more specific about what lights aren't working. The BCM simply reads the combination switches, then sends commands to the IPDM via the CANbus. The IPDM supplies both the lighting system and wipers from the high side (power is supplied, not ground) and the two headlights use different grounds, E22 grounds the IPDM and the righthand headlight, E46 grounds the wipers and the lefthand headlight. So there's no single ground which could cause total failure of the wipers and both headlights. The combination switch has all those functions on different legs of the matrix, so that would require an unlikely failure of more than one leg. So my guess would be that only an internal IPDM failure could kill both without killing anything else, but more details are needed.

[stoopideric]

So both headlights and the wipers either work correctly or they don't work at all.

I had replaced the engine and for 2 weeks everything was fine then this issue popped along with a slow overheating problem. When I hook up with my BT OBD reader I see 0% duty cycle and it never charges more than ~13.5v. I have read that the variable charging system can be problematic on these.

[VStar650CL]

That's true, but if the problem is the smart charging and not the alternator itself, then it's easily fixed by snipping the PWM wire. Coupled with a slow overheat, I'd say it's more likely you have a belt tension issue. If you think voltage is contributing to the lights-and-wipers problem, then it's important to catch it in the act and get a measurement while it's misbehaving. Electronics rarely "freak out" at above 10.5V and usually have to go much lower before they misbehave badly.

[stoopideric]

I will look through diagrams to find the PWM wire and try that since it's a free and fairly easy

[stoopideric]

So I was paying closer attention this morning on my commute and it almost seems like the lights and wipers stopping happens around the same time. I clipped the PWM wire and the charge voltage came up but had no effect on the issues that I am having. The belt is fairly new and I don't see the tensioner bouncing around like it is loose. This one has me stumped not gonna lie

[VStar650CL]

If it isn't a charge issue then chances are your IPDM is going south. The IPDM's all use FET, Darlington, or integrated driver arrays to run the relay coils, so it's entirely possible a whole array is going south and those two items happen to be on the same one. Nissan doesn't publish any circuit board layouts for their C/U's, but it wouldn't be the first time I saw a bad chip take out multiple functions.

[stoopideric]

Are the IPDM modules cross compatible? Mine is a 284B71BN3A from a 2012. I found someone that has one from a 2011 but it is number 284B71BN0A. Do you know if that would work?

[VStar650CL]

Those numbers aren't cross compatible, but there is a supersession for the 1BN3A to a 1BN6B, either number will work. Both are used on the 370Z as well as the G's, so there are a crapload of used ones listed on eBay. You shouldn't have any trouble finding one.

[stoopideric]

So after replacing the IPDM I still don't have headlights or wipers. If I unhook the negative cable for a while then they will work but then after a day or so they stop working.

I am also still having the overheating issue that I can't figure out. New thermostat, radiator cap, radiator is new, bled the system for days, no symptoms of a head gasket failure, fans work. If I run my heater wide open then it will never overheat and if it does overheat and I turn the heater on it will come down and stay down. I do have an exhaust leak on the header idk if that can cause the issue or not.
I'm at the point now where I have to wait until I have the money to take it somewhere because I am out of ideas.


On a side note I really appreciate all of your help VStar

[VStar650CL]

Yah, I don't think there's much else you can do without an expensive scanner which can read the BCM and IPDM. Unfortunately the combination switch is a "matrix" type which is almost impossible to check with a voltmeter. You need to pick the BCM's brain to see if it's working right. Same for the IPDM, you need to pick its brain to see if it's receiving the requests when the switches are thrown. Without that you'll probably do a lot of chasing your tail.

Vis the overheating, did you change the radiator hoses? Sounds like maybe the lower is delaminated and you have a partial blockage under suction.

[stoopideric]

Well the overheating was a clogged radiator, I just replaced it May but oh well.

Still haven't gotten a chance to get it hooked to a Consult scanner yet. I did swap in a used IPDM but the same problem still exists.

[stoopideric]

So just out of curiosity is the ecu PN and BCM PN tied to each other? I found a used set for my ride but the BCM is a different PN than stock. IF it swap both the ECU and BCM would they funtion properly?

[VStar650CL]

You might get away with changing both at once provided you have keyfobs from the donor, but that doesn't guarantee the BCM's other functions will work if it's the wrong p/n. The donor BCM can be a superseding or superseded number, that's okay. The dealer parts department can print you out a "supersession chain" for whatever p/n is in your car, any p/n in the chain will work.

[stoopideric]

I just wanted to follow up and post my findings. The first thing I found out is that I am an idiot, secondly the electrical problem turned out to be corrosion on the positive cables that attach to the fusible link at the battery.

I am still dealing with the slow overheating issue. I have put a new radiator and I will get a couple of weeks before it starts overheating again.

[VStar650CL]

Radiators don't clog in a vacuum (pun intended). If you're continually clogging them, it usually means one of two things. Either there's major corrosion and scaling inside the block, or somebody put sealer in the system. In either case you probably want to flush it with a very strong agent like BG or CLR Pro, then rinse and drain it through the lower hose and not the drain plug.