E220 Cab Intermittent immobilizer problem

[Witwill]

Hi

I'm in real need of some help as i'm about to go crazy!!

My E220 was parked up for a couple of years while i was working away. Since putting it back on the road I've had a couple of niggle to deal with but this is the worst. Sometimes the sensors just do not work (the door one stopped working before i parked the car up) but the boot one worked fine. Now the boot will work for a day or a week then suddenly nothing (AS THEY WORK THE IMMOBILIZER IT MEANS THE CAR WONT START). Occasionally the door sensor starts working. Its been into the garage a couple of times but they say they cant find a problem (thats because its intermittent and doesn't happen when they test it). because its happening with both sensors i think it may actually not be the sensors but another part. Please any help would be appreciated as I've had to leave it several times and take a cab.

 

[Dec]

You need to state what year the car is.
Describe what kind of sensors are on on the doors and boot.
Are there any lights flashing when the fault is present.
Describe what kind of remote or keys that you use.
Do you have a spare remote control or key.

Dec

 

[Witwill]

Hi sorry


It's a 1996 (N) model the sensors are factory fitted one in the door handle (only on the drivers door) and a little square one on the boot. Ordinarily they flash green when you open it and red when you lock it. The Immobilizer automatically kicks in about a minute after you turn the engine off. When the fault is present you get no lights at all. I've replaced the key (£200)!! And that's not the problem. FYI there aren't any sensors on the back if the rear view mirror as some people think there should be!

 

[kth286]

So it's a 124 car ?

 

[Witwill]

So it's a 124 car ?

Hi

Yes it's a 124 series

 

[Witwill]

Yes it's a 124 series

 

[Dec]

When you turn the engine off, you say the immobiliser kicks in, how do you know it kicks in?
What do you have to do if you turn the engine off and then want to start the car again after about 2 minutes?

Is there any other remote control for the car other than Mercedes one button flip out key?
You might just have an alarm that automatically arms itself after one minute from when you remove the key from the ignition, I think it is called Passive Arming in the alarm world.

Dec

 

[Witwill]

Hi
The hazard lights flash when the immobilizer kicks in.

To re start the car you have to point the key at one of the sensors and press the (single button flip) key to disarm it. Mercedes Benz confirmed it was quite a standard factory fitted system in the nineties

 

[Dec]

That all sounds like Passive Arming, when you turn the engine off and you take the key out of the ignition and exit the car, will the doors lock after 1 minute or do you have to press the remote button?

The 2 year lay off cant have been good for the alarm IF it has back up batteries inside it, how many wires go into the alarm siren? And will the siren sound if you intentionally trigger the alarm?

Can you describe the alarm siren or better still a picture of it would be useful.
I presume this is a UK car?

Dec

 

[Witwill]

Hi

Yes it's a uk car. I'll take a pic of alarm and post. It does not lock doors automatically. I turned the siren off years ago as a friend of mine valeted the car for me and got water in the siren and it started going off randomly. ( that was years ago and I'm sure it has nothing to with the current problem).

 

[kth286]

starting with the basics - have you replaced the key fob batteries with new and re synchronised the key to the car ?

 

[jibcl500]

Sounds like you have the dealer fitted alarm immobiliser fitted to your car, it can be bypassed easily so the car will start regardless without lock unlock to deactivate.

Would need to clarify what system you have fitted first though.

jib

 

[grober]

LOTTA CHANGES to the factory immobiliser set up around that time. You need to establish exactly which system factory or after market you are dealing with e.g.
http://www.startekinfo.com/StarTek/outside/12264/disc_2/Program/Chassis/80-400.pdf
From the symptoms you might have a problem with the N54 IR remote control unit rather than the alarm itself as it will always take its arm/disarm commands from the signals coming from remote control units. WHEN THERE ARE NO LIGHTS AT THE RECEIVERS DO THE DOORS STILL LOCK UNLOCK??

 

[Witwill]

Yes it is factory fitted and I bought a 2nd key at a cost of £200 but it hasn't made a difference it was expensive but at least I have a spare now. Guessing the easiest way is to find someone to bypass the Factory fitted immobilizer and then fit a new one!!

 

[Witwill]

When there are no lights on the receiver nothing happens at all. It happened again today luckily it started to work again after about 10 mins. But sometimes it could take an hour or more. And I could go for a week with no problem at all!

 

[grober]

When people mention cabriolets I always suspect water leaks or condensation. It's possible that some of the circuit boards have become damaged by water ingress. Yo would be amazed at how well they continue to function even when badly corroded ---- when dry---- but show em a little more water or damp and faults start to appear-- can give rise to intermittent faults you describe. Well worth taking a look at all those components to see if there are any signs of water ingress now or in the past.

 

[grober]

When there are no lights on the receiver nothing happens at all. It happened again today luckily it started to work again after about 10 mins. But sometimes it could take an hour or more. And I could go for a week with no problem at all!

This would suggest [ no door locking/unlocking--no receiver lights ] the problem lies with the IR system somewhere- first place I would check is the IR CONTROLLER under the rear seat.
PS I would also check/clean up the contacts[ they develop a film of corrosion] of all the fuses in fuse box under the bonnet- not sure which one supplies the alarm/IR system but think its Fuse B 8A and Fuse C 16A

 

[Witwill]

Condensation sound very possible. I think the vents have become blocked as I get condensation building up whenever the car is left locked for any length of time. It started after it was packed up for so long.

 

[jibcl500]

When there are no lights on the receiver nothing happens at all. It happened again today luckily it started to work again after about 10 mins. But sometimes it could take an hour or more. And I could go for a week with no problem at all!

Where are you based?
jib

 

[Witwill]

Lee Green southeast London (Lewisham). Where are you?