P38A Signs of a faulty BECM?

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Digweed

Active Member
Posts
120
Location
Ireland
As above. What would the signs of a faulty becm be? '01 2.5d with nothing electrical working inside, windows, mirrors, lights for eas nothing. interior lights work when turned on, mirrors dip when put in reverse. Interior mirror is autodim but it doesn't when lights are turned on. I had a look at the pin connections for the window control pack and found the power and ground wires for it and I'm not getting any power across them. Would this be a sign of a faulty BECM? The EAS has been doing my head in too - swapped out all the o-rings in the pump and the block and then the pump decides to give up the ghost! Have to get another one, but I'm still not getting any of the leds lit up on the dash like I've seen in some other posts. I get the 35mph message on the dash but nothing else. :(:(:(
 
Start by looking at the under bonnet fuse box for signs & smells of burning. Is the carpet wet in the drivers footwell?
Bit early to start thinking the BECM is at fault.
As kds said the auto dip mirrors only dip with the light from on coming vehicles.
 
kds said:
Not much help but the only one pretty sure about is the mirror, it only dims with on coming cars headlights when dark, no doubt somebody will pop in to help.
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Tried turning the lights on and covering the light sensor on the back of the mirror, shone a torch on the rear facing sensor but no joy.
 
Datatek said:
Start by looking at the under bonnet fuse box for signs & smells of burning. Is the carpet wet in the drivers footwell?
Bit early to start thinking the BECM is at fault.
As kds said the auto dip mirrors only dip with the light from on coming vehicles.
Click to expand...

I had a look at the fusebox, haven't taken it out though. Looks clean from the top, some of the relays were replaced already, found a few in the car, one was down between the fusebox and the body. I don't think the carpet is wet, it felt damp once but that may have been me getting in to and out on a wet day. I've read about the few damp problems in that area. If it's the heater o rings would it be wet up to the bulkhead or does it run down a channel to the floor?
 
Digweed said:
Tried turning the lights on and covering the light sensor on the back of the mirror, shone a torch on the rear facing sensor but no joy.
Click to expand...
I would have thought that the dipping mirror is the least of your worries, sort the other problems and you may well find that the dipping works again.
 
Digweed said:
I had a look at the fusebox, haven't taken it out though. Looks clean from the top, some of the relays were replaced already, found a few in the car, one was down between the fusebox and the body. I don't think the carpet is wet, it felt damp once but that may have been me getting in to and out on a wet day. I've read about the few damp problems in that area. If it's the heater o rings would it be wet up to the bulkhead or does it run down a channel to the floor?
Click to expand...
Lift the carpet at the seat end and check. As for the fuse box smell it for burning. It wouldn't hurt to take it apart, the main feed often comes loose.
 
Would that have an effect of no voltage showing across any of the fuses in the fuses box under the seat with ignition in position 2?
 
Lift the carpet because the the foam on the back of it soaks in the water and yer it runs down the wiring channel straight to becm so check carpet properly
 
Datatek said:
Lift the carpet at the seat end and check. As for the fuse box smell it for burning. It wouldn't hurt to take it apart, the main feed often comes loose.
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I had a quick look under the carpet, it felt damp but not wet (as damp as any vehicle sitting for 4 or 5 weeks on the coast would be). i took the fuse box out and i dont see anything wrong with it. There's a little bit of corrosion on one of the through pins but that cleaned off with a blast of contact cleaner. I gave it a good blast of cleaner between the boards to be sure.
 

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Digweed said:
I had a quick look under the carpet, it felt damp but not wet (as damp as any vehicle sitting for 4 or 5 weeks on the coast would be). i took the fuse box out and i dont see anything wrong with it. There's a little bit of corrosion on one of the through pins but that cleaned off with a blast of contact cleaner. I gave it a good blast of cleaner between the boards to be sure.
Click to expand...
Damp may be enough to cause condensation inside the BECM and/or corrosion in the connectors. that's why you should always have the aircon on as it dries the interior.
 
Datatek said:
Damp may be enough to cause condensation inside the BECM and/or corrosion in the connectors. that's why you should always have the aircon on as it dries the interior.
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Thats my goal for this :) :) :) nothing electrical works inside bar the central locking and all the various fecking alarms/beeps/bongs going to tell me there's something wrong :). Wing mirrors, windows, radio (turns on but I've no code for it), none of the EAS lights come on, sunroof, nothing works. I got the electric seat working but that was only because it had been plugged out. I've a feeling the SRS fault I get on the dash is just the seat airbag disconnected, it had been my plan today to fit a new connector to the two wires but I got pulled away. I've the battery disconnected now so I might take out the BECM module and give the plugs a clean. Can it be opened up or does it need specialist tools to get in? I've also finally ordered a diagnostic tool! I went with the Hawkeye in the end, I couldn't justify/afford spending more than I spent on the car in the first place to get a novocom.

Grrrrrr said:
Have you looked in RAVE for where the earth points are and checked they're all good?
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I had a look at the RAVE but I didn't have a chance to day to look at them. I tested for voltage across the fuses in the BECM fusebox with the ignition in Pos.2 and there was no voltage reading across any of them, might this be a problem?
 
If there's no volts getting to BECM, the issue is more likely to be at the fusebox end, or a bad earth somewhere. Does the car even start up ?

Start at fusebox, and check each feed before & after the relays. Check the permanent 12V feeds first.
 
pwood999 said:
If there's no volts getting to BECM, the issue is more likely to be at the fusebox end, or a bad earth somewhere. Does the car even start up ?

Start at fusebox, and check each feed before & after the relays. Check the permanent 12V feeds first.
Click to expand...
 
Digweed said:
Thats my goal for this :) :) :) nothing electrical works inside bar the central locking and all the various fecking alarms/beeps/bongs going to tell me there's something wrong :). Wing mirrors, windows, radio (turns on but I've no code for it), none of the EAS lights come on, sunroof, nothing works. I got the electric seat working but that was only because it had been plugged out. I've a feeling the SRS fault I get on the dash is just the seat airbag disconnected, it had been my plan today to fit a new connector to the two wires but I got pulled away. I've the battery disconnected now so I might take out the BECM module and give the plugs a clean. Can it be opened up or does it need specialist tools to get in? I've also finally ordered a diagnostic tool! I went with the Hawkeye in the end, I couldn't justify/afford spending more than I spent on the car in the first place to get a novocom.



I had a look at the RAVE but I didn't have a chance to day to look at them. I tested for voltage across the fuses in the BECM fusebox with the ignition in Pos.2 and there was no voltage reading across any of them, might this be a problem?
Click to expand...
No live feed to the BECM or the fuse box would certainly cause problems, that goes back to the under bonnet fuse box.
 
Datatek said:
No live feed to the BECM or the fuse box would certainly cause problems, that goes back to the under bonnet fuse box.
Click to expand...
Put the fusebox back in today after a good cleaning, checked all the ground points that I could get to (couldn't get to the ones in the rear of the engine bay) looks like someone has already been in there some of the retaining nuts were out of the holders. all the ground points looked ok, took them all off and gave them a rub with some sandpaper and finished off with contact cleaner. the floor is dry as a bone, what i thought was damp when i felt under it is the plastic backing on the carpet. I'm at a bit of a loss now as to what to do. The car starts and drives no bother but the interior electrics are stumping me.
 

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The saga continues with this thing! Disconnected the battery and took it the plugs from the becm sprayed in some contact cleaner just in case there was a bit of corrosion there. Hooked everything back up and started her up. She ran lovely (still nothing working inside) i put in the radio code that i got today, radio works! After about ten minutes messing about with the radio there was a couple of clicks and a new set of faults came up. "Electrical fault" "fuel gauge fault" and "temp gauge fault" and the horn started going off. Even turning it off and taking out the key left the dash on and horn going had to disconnect the battery. This was the dash with engine off and key out!
 

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