P38 Fuse 6, 7 and 17 HELP!

I call upon the collective wisdom. I have a 2002 P38 66k until now recently working ok. I have searched and searched on this one, but no one gives a conclusion to their problem.

Recently and intermittently car has cut out while driving, followed by gearbox fault, ABS fault Fuse 6, 7 and 17 failed. The car has re-start with no faults after a few moments. I have Hawkeye – no faults stored on EMS, TMS or ABS. a slight whir has been detected from the engine bay, I thought this was cooling fan/s on way out.

The battery has been a bit iffy for a while. So have been bench charging – off the car.

Now the car is turning on with faults and now won’t start (just cranks). Last time it started, battery 12.5v and Alternator giving out 14.4/5 at 2k rpm – then just packed in on the spot.

Changed battery as old one was shot. There seems to be an instant drain. Getting 12.08v on the three BECM feeds on the engine bay under fuse box feeds. When taken off the car the batter springs back up to 12.5v.

Wires under the engine fuse box (3yrs old) seems ok, as does the BECM (reconditioned 5yrs ago feeds under the seat.)

Could the noise be the alternator packing in? could the alternator cause the voltage drain and cause these fault codes and lack of power to the BECM?

Is it the dreaded BECM relay 15?

Any help gratefully received.

Owen

If engine stops and you coast to an halt in gear you will always get gearbox fault on dash. Alternator could indeed be cause of drain if a diode has failed. You do not say whether it is petrol or diesel.

Hi wammers, sorry 4.6 petrol
I did coast to a halt indeed, but engine died seconds after gearbox, abs fault came up. Can an alternator have an intermittent output fault? Would a drain cause all this electrical fault? I have been running the car on the spot on/off for a while to keep it active (not good I know for an alternator).
When I put the multi-meter on the back of the alternator (not sure which connectors) car not running but ignition on, the voltages jumps around constantly from 0.01 to 12.08 up and down erratically?

Owen89VSE said:

Hi wammers, sorry 4.6 petrol
I did coast to a halt indeed, but engine died seconds after gearbox, abs fault came up. Can an alternator have an intermittent output fault? Would a drain cause all this electrical fault? I have been running the car on the spot on/off for a while to keep it active (not good I know for an alternator).
When I put the multi-meter on the back of the alternator (not sure which connectors) car not running but ignition on, the voltages jumps around constantly from 0.01 to 12.08 up and down erratically?

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Change the alternator is a think the first step. On your car you should be getting 14.5 across battery when engine is running just after start up. And around that across battery at 2000 RPM with everything switched on. If a rectifier diode has failed battery will be drained by flow back through alternator PDQ.

Ok, worth saying I haven't had alternator fault on the message centre so far. Can I change the diode pack on the back of the alternator?

Owen89VSE said:

Ok, worth saying I haven't had alternator fault on the message centre so far. Can I change the diode pack on the back of the alternator?

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Take it to an auto electrician and get him to check it. Changing diode pack is a job not for the inexperienced. If it is at fault an exchange unit is preferable in my view.

Thanks
Has anyone had these faults and an alternator has fixed it?

If I disconnect the alternator - should the faults clear and the drain stop?

Owen89VSE said:

If I disconnect the alternator - should the faults clear and the drain stop?

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DO NOT run the engine with alternator disconnected. Take it and get it tested.

wasn't going too , not that I can! I meant just disconnect and turn ignition on........

Owen89VSE said:

wasn't going too , not that I can! I meant just disconnect and turn ignition on........

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Fuse 6 is H gate sensor module. Fuse 7 is engine ECM and Transfer box ECU. Fuse 17 is Stop lamp switch. All found in BECM fuse panel.

This is an easy one. Becm failure. I've repaired this fault many times, possibly in the hundreds over the years.

Rick-the-Pick said:

This is an easy one. Becm failure. I've repaired this fault many times, possibly in the hundreds over the years.

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Nice one Rick over to you.

Hi, thanks Rick, but a bit of an update.....
I have had hawkeye talk to the ABS ECU - tried again. Brake switch failure! Odd because when this first happened I have foot on brake changing gear, and when it stalled on the road. Can a brake switch (assume foot pedal) cause this?

I had my alternator refurbed you can only use geniun parts so its expensive but its all to do with the set point so find a good reconditioners and make sure they use geniun parts only

Owen89VSE said:

Hi, thanks Rick, but a bit of an update.....
I have had hawkeye talk to the ABS ECU - tried again. Brake switch failure! Odd because when this first happened I have foot on brake changing gear, and when it stalled on the road. Can a brake switch (assume foot pedal) cause this?

Click to expand...

Under normal circumstances a brake switch failing to switch senses would bring up ABS fault and maybe TC fault. That would not cause what you experienced though. Easy to fit a new one.

Hi Rick, how much to fix it?

The problem with this failure is that it can also restrict power to other ecu's. Ignore all faults until this is sorted. Everything will probably be back to normal once done.
Contact me through [email protected] & we'll explain what we need.

Hi Rick, email sent. Thanks Owen

Well, by way of an update and to help fellow P38 folk, the BeCM had taken upon itself to have a meltdown!
Rick was indeed and thus far correct. Went to see Rick Saturday and he and his soldering did the rest. So far so good and the car is (currently!) showing no faults. except a window, a few bulbs inside, puddle lamps........................ LOL.

Thanks Rick - until the next time!
Owen