P38 Central locking problem

Can anyone offer any advice?,I have a 4.6 1998 P38 which has central locking problems.

Basically using the remote key fob I can lock both rear doors and tailgate but the front doors remain unlocked.

If I manually lock drivers door with the key, the rear doors and tailgate lock but the front passenger door remains unlocked?

If I lock the front passenger door using the button inside, both rear doors and tailgate lock but not the drivers door.

Both front doors stoped locking at the same time, does anyone know the part that may have failed?

Thanks in advance Andy

Check fuses F9 and F22 in the base of the drivers seat (BECM fuse box). These are the ones that feed the front door outstations. Different fuses feed the rear doors and tailgate.

Thanks Derik, I checked the fuses and they were both fine, does anyone else have any idea where the problem could be?

The rear doors and the tailgate unlocking is controlled directly from the Becm not via the drivers door lock and front door outstation.
I have known both the drivers door motor to fail and the passenger door to superlock which has ended up with both front latches being replaced.
When the keyfob is operated, the front drivers door unlocks, this signals the front passenger door to unlock....the rear doors and tailgate unlock directly via the Becm NOT the signal from the front drivers door micro switches.

does anyone know the part that has failed and needs replacing? thanks again

ive got exactly the same problem!!becm was revirginalised?a few months ago,its going back to be rechecked tomorrow.both front locks were brand new.could it be the r/f reciever powering up the locks constantly and burning them out?whats the price of a box of matches anybody?

The rear doors and the tailgate unlocking is controlled directly from the Becm not via the drivers door lock and front door outstation.
I have known both the drivers door motor to fail and the passenger door to superlock which has ended up with both front latches being replaced.
When the keyfob is operated, the front drivers door unlocks, this signals the front passenger door to unlock....the rear doors and tailgate unlock directly via the Becm NOT the signal from the front drivers door micro switches

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Sorry Irish but I have to disagree with you on this one. The tailgate is controlled directly from the drivers door central locking switch on the lock. If the unlock motor on the drivers door has failed, unlocking the car with the fob will unlock the other three doors but will not unlock the tailgate. This will only unlock when you unlock the drivers door with the key. It shows this on the circuit dia in Rave. I only found out when the unlock motor on my drivers door failed and I found the tailgate still locked until I unlocked the drivers door with the key. The front passenger door is controlled from the BECM the same as the rear doors.

Hi what is the solution to this problem as mine has started to do this.

Many thanks Steve

Hi what is the solution to this problem as mine has started to do this.

Many thanks Steve

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You'll have to be a bit more specific in exactly what it's doing and what it's not doing.

steveoooo,i think its a cunning plan by r/r to get all p38s off the road.is there anybody out there with the answer?Im away on holiday for three weeks on monday so i may have the solution when i get back(fingers crossed).keep you posted.regards alan.

just had the same problem on my drivers door !
so after hours with the multi meter i found that there is a issue with the becm sending power to the door.

the fuses f9 and f22 should have 12 v, which they do, but on checking the output from the bmec the purple black power wire had less than 1 volt this wire goes to the door via the white plug in the A post should have 2 black wires( earth) and purple/blue and purple/back( 12 v each)

I rigged up a 12 v supply to the plug in the door and it all works !

next step is to have a look in the bmec not sure what im going to find but hopefully a burnt track or blown diode , can any one comment or provide pics of the inside front ?

FYI the plug ( c326 ) is the middle connect on the bottom row at the front

hex said:

just had the same problem on my drivers door !
so after hours with the multi meter i found that there is a issue with the becm sending power to the door.

the fuses f9 and f22 should have 12 v, which they do, but on checking the output from the bmec the purple black power wire had less than 1 volt this wire goes to the door via the white plug in the A post should have 2 black wires( earth) and purple/blue and purple/back( 12 v each)

I rigged up a 12 v supply to the plug in the door and it all works !

next step is to have a look in the bmec not sure what im going to find but hopefully a burnt track or blown diode , can any one comment or provide pics of the inside front ?

FYI the plug ( c326 ) is the middle connect on the bottom row at the front

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Use a strong magnifying glass and look for dry (cracked) solder joints. I have a BECM in bits, I can go take photo's if it would help.

Datatek said:

Use a strong magnifying glass and look for dry (cracked) solder joints. I have a BECM in bits, I can go take photo's if it would help.

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Datatek , thanks for the offer, what i want to know is is it a single board or multiple boards and if i can check the connection and voltage with a multimeter

hex said:

Datatek , thanks for the offer, what i want to know is is it a single board or multiple boards and if i can check the connection and voltage with a multimeter

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It's 2 boards, a logic board and a power board with relays and power MOSFFETS. Be careful to ground (earth) yourself to discharge static build up from your body before touching any of the internals or you may destroy things
You can trace the connection with a multi meter either on Ohms with the power removed or volts with the power on, but it's often quickest to just look for bad solder joints, corroded tracks etc

Did anyone manage to find out the problem, as it sounds Like the same problem I'm having.
Cheers.

in my case it was a broken track on the bmec, folowed datatec's method and found that the board is double sided some tracks are on the top and some on the botom.
the track on the top was ok but the bottom one had lifted and cracked

Had similar problem first my passenger door stopped working on the fob, then drivers door stopped working but both rear and tailgate continued to operate on the fob. I had to replace both front door mech's, and also replaced r/f with the upgraded version as the old type apparently burns out the door mech's even with the blue wire disconnected, having done this touch wood i have had no further problems. Hope this helps.

Wow, I thought I was the only one with this problem, been going on since oct 2011, nd still ent sorted! started off with battery going flat, then front doors not operating by key fob, had driver door latch replace worked of for two weeks, then stopped, turns out it was a wiring problem in drivers door, then had pass. door latch replaced, yippi! both doors work from key fob, but when I lock it up the head lights flash instead of the indicators??? 10 days after this was all fixed, im back to square 1, both front doors not unlocking from key fob! also, has any one ever experianced the 4 indicator lights being on solid when they wake up in the morning? I'm lost for words... any help would be apprieciated as this has cost me £900 so far, and the bloody engin imobilesed this afternoon, good job I had spare set of keys!

In answer to flavell yes i experienced more or less identical problems so can understand the frustration but have managed to sort mine out by having diagnostic done and listening to the help on here, then carrying out the work i stated and as said so far so good.

Hi there sorry for hijacking your thread but i have got same prob. (p38 2.5dse 1996) went to open tailgate and it wouldn't work, so after reading many threads thought it must be the push button as read they rust up inside, so managed to get the panel off the inside and operate lock manually to open it, stripped the button down and it looked almost new, mmm me thought, got multimeter out, tested power to button and have got 12v on one wire and 5.7v on the other wire, is this norm?. so went to lock the car and noticed that only the rear doors are locking on the fob and only drivers door is locking with the key, when sat in the car and you press the lock button down it only locks the drivers door. have i got a dodgy lock on a door somewhere of could it be the rf?