J10 Main Beam remained on with no control

[panda986]

Hi all,

First time poster but have been on/off here for a long while to find solutions to my issues for my Petrol 1.6 +2. But this time, I have not been able to find anything so far.

Since a recent battery recharge and refit back into the car, the main beam is now stuck on whenever the engine starts. I cannot switch it between dipped or main nor turn it off, it just remained on. Luckily, when I turn the ignition to off completely, the light will go off so as not to drain the battery. (Seems related but the rear wind screen wiper also comes on and not controllable as well).

I have visually checked the Fuse (F47, 48 -- according to Haynes), and can take it out to just give me the dipped beam (but on the dash, it will still show the main beam is on). I was about to go check the relay, but I read that they are hardwired into the IPDM, so there is no parts to check or replace (please correct me if I am wrong). I am running out of idea, any suggestion? Given it remain stuck on, rather than not working like most other questions, could it be a Grounding issue?

Thanks in advance.

[calnorth]

It certainly looks weird but the rear wiper is controlled by IPDM from BCM. IPDM manages the CAN Bus reverse switch signal...so is the wiper operating in neutral?

BCM sends CAN Bus commands for both HI/LO Beam via IPDM to the headlamps. IPDM does the powering.

BCM detects what particular combination (driver) switches do

Whats common amongst that lot? Don't think its grounding. IPDM seems to be putting both HI lights/rear wiper ON? If IDPM is faulty internally I don't think spares are available nor is their an internal diagram for it AFAIK?

[panda986]

Thanks for the reply calnorth.

Even in neutral/off position, the rear wiper still operates.

So from your info, it could be the BCM (though I am not 100% sure what it is, but assume it is some control unit that switches are connected to?) is playing up sending the wrong signal? Or the actual switches for them are malfunctioning... though I would imagine both the headlight and rear wiper controls are different given they are on different stock.

Finally I had a more detail look at the Haynes manual's wiring diagram, both the rear wiper and the headlights are linked to the Fusible link box (FLC - petrol model). And none of the other are using that.... so it may be down to that? Its the one thing that is common to both and they are both stuck on...

Wiper

Lights

[calnorth]

The diagrams I have are somewhat different to Haynes. I don't think fuses/links are the problem

For the HI lamps:
The illuminated indicator in the cabin (Combination Meter) is slaved to the CAN Bus which means an ON signal persists from BCM. BCM has either been driver switched to HI or a fault is driving it HI as though its a driver command. That signal needs isolating rather than the fuse.

Rear Wiper:
BCM monitors the wiper motor internal stop switch to park it correctly. The rear wiper is controlled by a signal processor and driver selection plus reversing. As with the headlamps I think such signals to BCM need isolating.

Nissan diagnostics aren't useful here but I suspect there is a case for them to examine the CAN Bus signals (signal analyser) anyway. Its impossible to routinely switch systems ON/OFF without a distinct CAN code (data packet) that matches related signal processor addresses (identification).

I think the only thing you can do is disconnect the signal inputs to BCM from the combination switching (drivers controls). The diagram I'm looking at is Nissan Diagnostics which may not be 100% correct due to age/origin...see attached:

...................................

[calnorth]

Rear Wiper Schematic (Nissan J10) . Where CAN BUS lines are disconnected the sub system being disconnected should be replaced with a terminating resistor of approx 120 ohms.

[panda986]

Thanks for the info Calnorth, much appreciated.

From looking at this, it would seems BCM is a likely suspect (or probably a certain part of it), will see if I can get to it to visually inspect it first or see if anything stand out around it connection wise. Will also check the combination Switch as well. Will update back soon.

Though if it turns out to be anything else, then it will be out of my depth and will be looking for a garage (but hopefully arming with some knowledge will help)... Luckily my wife's car is still usable and can make things work.

[calnorth]

Thanks for the info Calnorth, much appreciated.

From looking at this, it would seems BCM is a likely suspect (or probably a certain part of it), will see if I can get to it to visually inspect it first or see if anything stand out around it connection wise. Will also check the combination Switch as well. Will update back soon.

Though if it turns out to be anything else, then it will be out of my depth and will be looking for a garage (but hopefully arming with some knowledge will help)... Luckily my wife's car is still usable and can make things work.

i suspect Nissan dealers etc will look for DTCs which may or may not help. After that its module replacement and there's only two really. Will be good to know the outcome...

[panda986]

hi All,

Finally got around to the bottom of the issue. Nissan garage took a look and found some wirings between the control stock and the BCM had came loose and it took them just over 2 hours to find and fix the issue.

Also the technician said the reason the main bean is stuck on is because it was a fail safe system. In case it cannot detect any input, the system would leave the light on instead of off (for safety reason). Hope this helps someone next time.

[calnorth]

hi All,

Finally got around to the bottom of the issue. Nissan garage took a look and found some wirings between the control stock and the BCM had came loose and it took them just over 2 hours to find and fix the issue.

Also the technician said the reason the main bean is stuck on is because it was a fail safe system. In case it cannot detect any input, the system would leave the light on instead of off (for safety reason). Hope this helps someone next time.

The diagnostics have procedures to follow and a lot of it is about wiring and path testing. BCM often has Fail Safe listed amongst the system descriptions for various fault functions. Trouble is the diagnostics I have are not 100% accurate as regards module inter wiring etc.