W202 central locking not working

[vagman]

would be grateful for any help on this matter. never had a problem with my dad's 95 w202 c220d remote central locking before. changed the batteries in both remotes and now the central locking won't work. thought that it was simply a case of re-synch the keys which I did as per earlier posts with no success. new batteries work fine tried camera etc no probs there. I have noticed that the central locking dash button does not work either. never had a problem with this before either. checked all fuses but as the central locking is vacuum still can't work out what it might be.

even disconnected the central locking pump checked for moisture etc. refitted still no success.

at my wits ends as I have to lock and unlock manually via the passenger door. red and green lights all worj on reae view mirror. how do i check if it is the pump without buying a replacement

cheers

 

[television]

The early 202 pumps can be bought for around £25,,, Rob Parker sells them for that price, I have a good one here but minus the rubber connecting pipes inside.

I take it you have checked the fuses

 

[vagman]

checked the fuses under bonnet and in boot.

 

[Dec]

would be grateful for any help on this matter. never had a problem with my dad's 95 w202 c220d remote central locking before. changed the batteries in both remotes and now the central locking won't work. thought that it was simply a case of re-synch the keys which I did as per earlier posts with no success. new batteries work fine tried camera etc no probs there. I have noticed that the central locking dash button does not work either. never had a problem with this before either. checked all fuses but as the central locking is vacuum still can't work out what it might be.

even disconnected the central locking pump checked for moisture etc. refitted still no success.

at my wits ends as I have to lock and unlock manually via the passenger door. red and green lights all worj on reae view mirror. how do i check if it is the pump without buying a replacement
cheers

Remove the unit from the car and with a battery charger put power to the vacuum pump motor at the two terminals (Black & Brown wires)at the end of the motor, if the motor is good it will blow or suck air though its White pipe (pipe can be seen in picture)

Dec

 

[horgantrevor]

i would start with fuses and go from their

if light is coming on on the remote then you can rule that out

also what kind of mirror have you how did you reset the remote so we can be sure you did it right

also put key in ignition after you have reset it and leave in position 2 for ten min or so

can you see if the car is running can you make the headrest in the back fall or headlights move up or down

this will tell if the pump is dead or not

but i would check fuses fires dont forget the few in th e booth next to battery

keep us posted

 

[television]

i would start with fuses and go from their

if light is coming on on the remote then you can rule that out

also what kind of mirror have you how did you reset the remote so we can be sure you did it right

also put key in ignition after you have reset it and leave in position 2 for ten min or so

can you see if the car is running can you make the headrest in the back fall or headlights move up or down

this will tell if the pump is dead or not

but i would check fuses fires dont forget the few in th e booth next to battery

keep us posted

The locking does not work from the internal button or with the blade from the key so it looks like a pump fault

 

[vagman]

cheers guys, I will remove the pumop this evening and try to eliminate this. will keep all of you posted on my developments

 

[television]

Do not forget that I have a good one here if you want it

 

[vagman]

removed pump. took apart as per photos and advice above. tested with car battery power supply and pump works. before i removed from car i tested the rear headrest button and that worked also.

i plan to put back in the car tomorrow and retest again. Before i removed pump from car this evening the dash central lcoking button was still not working and neither were either of the two keys.

In regards to key synch I have been puching the key button and holding in while i turn the key to the position 2 before starting. Is this the nest approach.

many thanks for all your help to date.

 

[Dec]

Did you test the motor on its own, without going through the cuircut board?

Dec

 

[Dec]

If you didn’t see a White tube connected to the vacuum pump, but Yellow tubes only, then the rear head rest dropdown and the headlamp adjust are not controlled by the vacuum pump, the engine has to be running or I think, has to have been recently running for those two items to work. I think yours is the same as the one in picture which is a 1995 and doesn’t operate the headrests or headlamps hight adjuster?... later cars might be diffrent?

So the pump motor works with 12v, I should have also said to reverse the wires (reverse the polarity) the pump should run in the opposite direction… it blows air when run in one direction and should suck air if run in the opposite direction… when the polarity is reversed.

If the vacuum motor is good then that leaves the printed circuit board or the components on the rear of it as the most likely cause of the fault.

See the solder joints 1 and 2 on the bottom of the circuit board, pictured below, the are where the Brown and Black wires that feed the vacuum motor come from, check these joints out as the are the power supply for the vacuum motor. The two joints in the picture are in poor condition (Brown staining)

Check also the rest of the pumps circuit board for other faults like bad solder joints/corrosion/damaged tracks.

Are there any Red and Green lights on the inside rear view mirror and on the door handle? If there are what are the doing when you press the fob button?

Dec

 

[vagman]

cheers Dec,

mine is a 95 c220d; pump exactly as above pic. no yellow tube only white and now that i remember the engine was indeed running whenever i checked the rear headrest button.. ran power direct to the pump itself and not the circuit board. will take apart again today and reverse the polarity and check over the circuit board again for any visible damage. will update

 

[Dec]

Are there any Red and Green lights on the inside rear view mirror and on the door handle? If there are what are the doing when you press the fob button?

Dec

Any comments on the Red and Green lights, if you have them… just need to eliminate the possibility that the inferred receiver is not working and is not ”talking” to the pump?
It’s possible that the vacuum pump is ok and the fault is elsewhere, like in the wiring to the pump or inferred receiver.

Forget what I asked above, about the Red/Green lights… just read your first post again.

You will see the contraption pictured below, its what switches off the pump and I think its what reverses the polarity each time the pump is run so if it blowed last time then it will suck next time that its run. Adjusting it won’t be of any help to you but its worth understanding what it is and that it does, more, here… http://forums.mercedesclub.org.uk/showthread.php?t=89011&page=4

Dec

 

[television]

The pump sucks if asked to or blows when asked, it does not reverse each time it runs, it is the command that is given the determines the direction of the pump. This is given from the 2 buttons on the key or switch in the car or switches in the door locks

 

[vagman]

took pump part again. then reassembled and refitted in car. central locking would still not work either via key or dashboard button. car would not start. flashing red then green light etc.

took pump out and sprayed pump terminals with wd40 reinserted and hey presto central locking worked both from button and remote and car would start fine. proceeded to try this out for 6 times and worked on each occassion.

left car went into house made a coffee felt all pleased with myself. went outside tried remote central locking on key and car would not open. back to square one.

all fuses are ok. no leaks in system. have i just got a lazy pump which is on the way out and needs replaced. don't mind fitting a replacement pump just want to make sure that it is the pump.

also is there a way to disable the immobiliser and still have the remote central lcoking etc. have read different threads on here about this topic and while i do understand the whole legal dilemna my car is 17 years old and i'm trying my best to keep it on the road.

happy for any advice on either topic

cheers

 

[Dec]

I don’t know how it’s disabled, the immobiliser is something that I don’t like on my car due to all the faults that I see on the forum about it, if knew how, I would be doing it myself.

You seem to have an intermittent fault, probably, as suggested earlier a broken joint somewhere on the Printed Circuit Board.

You could give it to an experienced TV repair man to have a look at it, that is if you aren’t too familiar with ths sort of work yourself.

Dec

Edit, What way were the lights the mirror Red and Green lights flashing?
Togeather or Alternatley?

 

[television]

There is nothing in the PSE pump that can affect the immobilizer to my knowledge so I think you may have to disconnect the alarm part.

 

[vagman]

alternatively Dec. red then green then red etc. turned key to position 2 while holding button to get started. after this will start first time every time as long as you do not press the central locking button. think i will replace the CL pump. local benz breaker is quoting £20.

 

[vagman]

cheers Malcolm. any tips or pointers to where i sholuld look for advice on how to do this

cheers

 

[television]

It is normally under the passenger kick panel