Body control unit replaced

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Mid-life-crisis

Active Member
Posts
116
Location
Northern Ireland
Hi all
2002 L322 3.0 tdi
Yesterday I replaced the body control unit because I couldn't get rhe headlight washers and wipers to work (yes the motors are ok as is the washer pump - not sure about the relay)
Anyway, today the lock and unlock buttons on the key fob doesn't work.
Does the BCU also control the central locking and if it does, can it be reprogrammed to the key
Thanks
P.s the headlight washers and wipers still don't work!
 
^^^^what he says, it didn't fix it so best to put old BCU back.
Have all the below conditions been met?


Headlamp Wipers and Washers
The headlamp wipers and washers are only active when the headlamps are switched on and the ignition is on. The
wipers and washers are controlled by the BCU which limits their operation to preserve washer fluid in the reservoir.
With the ignition and lights on, headlamp wash/wipe is activated on the first operation of the wiper column control
switch in the wash/wipe position. The BCU then suspends headlamp wash/wipe activation for the next four operations
of the wash/wipe switch, with the headlamp wipers and washer activated on the fifth operation of the switch.
The BCU monitors the operation of the wash/wipe switch and maintains a counter to restrict headlamp wiper and
washer operation to every fifth operation of the wash/wipe switch. The BCU also maintains a timer which prevents a
second operation of the headlamp wipers and washers within a 3 minute period. The counter and timer are reset when
the ignition is switched off.
When headlamp wash/wipe is active, the BCU energises the washer pump twice per cycle. The headlamp washer
pump is powered for a 0.5 second period, 300 ms before the wiper motor starts. The BCU then initiates a 2 second
delay before powering the headlamp washer pump for a second 0.5 second period.
If the washer reservoir fluid level becomes low, the LCM, which monitors the fluid level, sends a message, via the I
bus, instrument pack and K bus, to the BCU which suspends headlamp wash/wipe operation to preserve the
remaining washer fluid.
 
Last edited:
Wow, thanks backinblack. I did know that the headlights on and ignition on were required, but I didn't know about the 3 minute prevention period. But I have turned the ignition off and retried and they still don't work.
The passenger side motor and the washer pump were both faulty and I've replaced them. I tested the relay as far as I could and checked the wiring and fuses are ok.
My IID tool doesn't report any faults.
And as the passenger side rear window sometimes drops of it's own accord and refuses all commands to rise (even through the IID tool), I thought the BCU was a fair bet.
Sorry if I upset you by wantonly swapping things Datatek
 
Its not as easy as just swapping ecu`s out, a lot of them have to be programmed to the motor, especially where the keys are concerned
 
Wow, thanks backinblack. I did know that the headlights on and ignition on were required, but I didn't know about the 3 minute prevention period. But I have turned the ignition off and retried and they still don't work.
The passenger side motor and the washer pump were both faulty and I've replaced them. I tested the relay as far as I could and checked the wiring and fuses are ok.
My IID tool doesn't report any faults.
And as the passenger side rear window sometimes drops of it's own accord and refuses all commands to rise (even through the IID tool), I thought the BCU was a fair bet.
Sorry if I upset you by wantonly swapping things Datatek
Don't think you upset him, you were just reverting to Main Stealer tactics ie.swop things till it's fixed.;):D
 
Wow, thanks backinblack. I did know that the headlights on and ignition on were required, but I didn't know about the 3 minute prevention period. But I have turned the ignition off and retried and they still don't work.
The passenger side motor and the washer pump were both faulty and I've replaced them. I tested the relay as far as I could and checked the wiring and fuses are ok.
My IID tool doesn't report any faults.
And as the passenger side rear window sometimes drops of it's own accord and refuses all commands to rise (even through the IID tool), I thought the BCU was a fair bet.
Sorry if I upset you by wantonly swapping things Datatek
Not the least upset:D
 
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