W210 Alarm/Immobiliser Problem

[peterdavis]

I have a 1999 W210 220CDI which has just done 100,000 miles.

For some time now I have had problems getting the car to start which I think is probably the immobiliser. When I turn the key to start nothing happens, after a couple of attempts it starts, this is intermittent as sometimes it starts first time.

Yesterday the alarm started going off completely randomly. I could stop it ok with the electronic key.

I have disconnected the battery for 15 seconds as I believe this resets the alarm? but no difference.

I have also had a problem getting the rear courtesy light to work, I have changed the bulb, checked the fuses, but it still won't work.

I know that there can be lots of problems with the W210 alarm system but does the above combination of faults point to anything in particular?

Thanks

 

[television]

The first thing I would do is to disconnect the alarm siren, they do have a sell by time, its under the front wheel arch liner at the top

 

[peterdavis]

Thanks for your rapid response.

Sorry to be dim but do I have to remove the liner? and is it offside or nearside?

When I bought the car I could only get a very basic Peter Russek Pocket Mechanic manual which tells you nothing at all about the alarm and its components.

Thanks

 

[television]

Yes remove the rear section of the near side and its up in the top corner, or should be

 

[Cole@MBS]

I suspect that the starting fault is the starter going down, common on that model.....

 

[television]

I suspect that the starting fault is the starter going down, common on that model.....

reading the post again it could well be that and a few simple test would confirm it

 

[peterdavis]

Now indicators, cruise control and fan as well!

Had the starting problems checked out by an independent who checked everything down to the ECU, concluded that this was the most likely cause. Sent the ECU off to be tested and came back with no faults. Refitted the ECU and initially all was fine ......... surprise surprise!

Then started having problems with intermittent failure of indicators, cruise control and heater fan and starting again.

Decided to have a good look at the components near the ECU and when I took the pins off the next unit along, i.e. towards the front of the car I found that there was fluid in the top of the unit, just where the bottom of the pins would be sitting. I cleaned it all out and reattached the pins, only problem is when I pushed them back in more fluid appeared.

It is now starting first time, but still intermittent problems with the other components. Not sure what this part is but would imagine this is the cause of my problems. Taken some photos of it with serial numbers etc.

Update ..... mmmm worked out that the item in question was the automatic transmission control unit; so unlikely to be the problem. Have now noticed that the rear courtesy light and both rear window switches on the rear doors are not working, however the rear windows work from the switches on the front centre console.

On checking the forums I have found one or two threads regarding the failure of rear window regulators causing these kinds of problems and funnily enough I replaced one of the rear window regulators a few months ago which could have been around the time that the other problems started but can't be sure. Not sure how to proceed, help needed.

Thanks
Peter