T

tommo1972

New Member
Hi, I've had a number of intermittent faults on my P38 DHSE which suggest there is a problem with the becm.
Faults have been:
Traction failure warning on display (most common)
Air suspension not working (about 3 times in 6 months)
Indicator lights stuck on (only done this once)
auto gearbox selecter display showing wrong gear (showed reverse when in drive) (again only done this once)
Radio lost code (done this twice)
Gave all signs of a flat battery (nothing electrical worked at all) only done this once.
All the above have been put right by locking/unlocking the car, sometimes with the key in door, then all is then back to normal.
Am I right with thinking this is the BECM at fault, and any ideas on whether its a fixable fault, or replace the BECM?
Any suggestions welcome!
thanks
Phil
 
Have you checked the wiring connections/plugs at the Battery/Becm/Fusebox for any loose or corroded/dirty connectors???


I'd be looking for any of the above first, as it seems to me your losing a stable power supply.....how old is your battery and whats its CCA???
 
Last edited:
Hi, not checked any of the becm or fusebox plugs yet, the battery was replaced when I first had it about 6 months ago, old battery was completely shot, replaced like for like with a 770 cca.
In fairness there were a couple of eas problems (perished air bags and lots of leaking joints in the pipework) which have all been replaced so that may not be related. The only fairly common one is traction failure.
 
I'll try that! The underbonnet fusebox? what corrodes? the fusebox itself or the connections on the plugs into it?
 
tommo1972 said:
I'll try that! The underbonnet fusebox? what corrodes? the fusebox itself or the connections on the plugs into it?
Click to expand...

Yes the under bonnet fuse box. Mine looked fine from the top. I had no burned or browned patches but when I eventually removed it and followed the steps on Range Rovers I found lots of the copper tracking badly burned including the main connector stud which had caused me to lose all power to the vehicle a few times.
 
tommo1972 said:
Hi, not checked any of the becm or fusebox plugs yet, the battery was replaced when I first had it about 6 months ago, old battery was completely shot, replaced like for like with a 770 cca.
In fairness there were a couple of eas problems (perished air bags and lots of leaking joints in the pipework) which have all been replaced so that may not be related. The only fairly common one is traction failure.
Click to expand...

All of that could be battery, alternator, corroded fusebox, bad earths or the actual battery wires corroded away inside the sleeving. If the carpet is wet in the drivers footwell it could also be condensation inside the BECM:eek:
 
Well up to yet, all the battery connections and earth leads have been checked, no problems found. Its been fine till today, when it decided to loose a feed somewhere, all windows needed to be reset, radio lost code, dash came up with gearbox fault, traction control, and engine disabled. An hour later it is back to normal again!! Currently got the fusebox out and apart ready for a mate to check for dry joints. The fusebox looks quite new in fairness, no obvious signs of any corrosion or burning.
 
Went to one last month with a wet drivers carpet and yes the Becm was damp inside and yes he was getting all sorts of false readings.
 
As a side issue there is a setting in the BECM called moisture alarm.
Mine is switched off. Anyone know what it does?
 
dave4x4 said:
As a side issue there is a setting in the BECM called moisture alarm.
Mine is switched off. Anyone know what it does?
Click to expand...


No one's brave enough to enable it unless they are living in the desert, incase the becm go's haywire.......:eek:........:rolleyes:
 
Moisture detect don't do anything.

There's nothing wrong with the becm if everything is working.

The becm is only a hub for all the other modules on the car.

I'd also look at the fusebox & connectors.
 
well the fusebox and becm are at my mates for checking, no obvious problems with either, both dry and clean inside. Will hopefully know soon! Think I would have prefered seeing an obvious problem!
Anything else I can be checking on the car while Im waiting??
 
I'd be inclined to be checking earth connections to body/return earths, also make sure your battery cables to neg/pos clamps/lugs have perfect continuity.

I've seen loose/burnt cable lug joints cause all sorts of problems...
 
well back to the drawing board! The fusebox and becm have been checked for dry joints, resoldered and put back in on saturday. This evening the car needs all its windows resetting along with sunroof and the radio needs it code, just as though the battery has been disconnected (it hasnt, nor has it been flat)
Does anyone know if one of the relays inside the becm could cause this? Although its not a really serious fault (on the plus side I know the radio code off by heart now) I fear it may get to a point where the car will just be dead one day.
 
tommo1972 said:
well back to the drawing board! The fusebox and becm have been checked for dry joints, resoldered and put back in on saturday. This evening the car needs all its windows resetting along with sunroof and the radio needs it code, just as though the battery has been disconnected (it hasnt, nor has it been flat)
Does anyone know if one of the relays inside the becm could cause this? Although its not a really serious fault (on the plus side I know the radio code off by heart now) I fear it may get to a point where the car will just be dead one day.
Click to expand...

You should have disconnected battery before playing with fuse box or BECM. When you remove the fuse box, what do you think is connecting all the systems together. Of course everything will want resetting.
 
The car was put back together saturday, everything was set and was used sunday monday tuesday and wednesday till evening with no problems
 
Well, touch wood, the problem has been cured. Replacing the power board in the bcm has stopped all the electrical niggles.
 
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