W202 Engine Immobiliser / Alarm?

[Csi031]

Really stuck

My 1995 C180 had a flat battery. Jumped started the car with leads and the car started fine. Drove for 45mins and parked car up.

When I came back to drive off. Engine turns over, car doesn't start. The usual flash of hazards to indicate alarm is off, doesn't happen. Actually hazards don't flash at all.

Tried recharging car battery to full. Key fob sync. Nothing works.

Any ideas ? Car has been towed back home and is sitting there dead.

I think it's engine immobiliser that's not deactivating.

 

[neilrr]

Fuel or spark, checked for both?

 

[Csi031]

Car is half full. Recently
Had new crankshaft sensor, coil packs and ecu unit installed.

 

[Dec]

Is there normally a Red LED on dash when the car locking/alarm is working properly?
What remote fob/s do you have and any other odd looking keys with the car?
Is there Red & Green LEDS on the door/mirror?
Is this a UK car?
Are the car battery terminals tight, do the hazard & outside parking lights work?

Dec

 

[Csi031]

It's a c180 elegance. Uk car

 

[Csi031]

It one one button fob. On the driver door there is a red/green led & on the rear view mirror.

I also have a flat credit card key for the car. That also doesn't disable the alarm. And just operates the central locking.

Battery terminals have been cleaned. Battery has been on charge all day and is fully charged. Car lights, radio etc all work.

Hazard lights work if I put hazards on. But they are not flashing at all to indicate alarm is being armed or disarmed.

 

[Dec]

Did you test the remote as described in above picture, also illustrated in the video below when viewed through a digital camera.

Do the Red & Green LEDs in mirror flash Alternately or Together when the ignition key is turned to position 2?

Have you checked all fuses, particularly relating to central locking/infrared.

Dec

https://www.youtube.com/watch?v=zQhwvjw29NA

[YOUTUBE]zQhwvjw29NA[/YOUTUBE]

 

[Csi031]

Hi Dec.

The red light in the mirror stopped working 15 years ago.

On the door, the red led is not flashing at all. Green led flashes when I press key fob.

Only Green light flashes when I turn fob to position two.

I've tried the camera. I cannot see blue light from key fob. I've tried it also with the credit card key. I've bought brand new batteries for key fob also.

 

[Csi031]

I have checked fuses. All are intact

 

[Csi031]

Both sets of fuses. Under the hood and boot

 

[Dec]

Seems to me the immobiliser is not being disabled, normally, when all is well, there are no lights flashing on the mirror when you turn the key to position 2.
Pressing the button on the flip out key, when you unlock, disarms the immobiliser, probably the Red & Green LEDs are flashing, Alternately (or the would be, if the Red was working) when you turn to position 2 , flashing alternately when you turn to position 2 means the immobiliser is not disarmed so the car wont start.

When you view the remote lens through a digit camera and press the button continuously, you should see exactly what you see in the video above, the Red light, to show that battery is ok followed by Blue/White pulsing light. If you don’t see the Blue/White light then the remote must be at fault and is not disarming the immobiliser.
Just try again to be sure to see if the Blue/White is not present, do it in a darken room.

It may be the remote fob button or some other part of the fob that’s at fault.

Dec

See this… repairing broken W202 Key fob. - Mercedes-Benz Owners' Forums

https://www.youtube.com/watch?v=lCqfivH9-Dg

[YOUTUBE]lCqfivH9-Dg[/YOUTUBE]

 

[Csi031]

Dec, interesting discovering. Using iPhone 6 camera, the blue white light of key fob is not visible. Using iPhone 4 camera, the blue white light of key fob is visible as bright as day.

The key fob is working. It means that immobiliser is not? Any ideas how it can be reset?

 

[Dec]

Did you try synchronising key fob.
Try more than one tiime.

Dec

 

[Csi031]

Yes. Point at mirror. Press button twice. Insert into ignition and turn to position 2. And wait for 30secs

 

[Dec]

Within 30 seconds, not "wait 30 seconds", either way it didn't work.

Dec

 

[Dec]

Unplug the electrical connections to the vacuum pump, for 10 minutes, to see if that resets anything.

See… https://www.google.ie/search?q=w202...hUBKcAKHVYoA7IQ_AUIBigB#imgrc=h6fhrkn3q5yFYM:

Dec

 

[Csi031]

Unfortunately no. I've tried syncing keys for over 2 hours. With no success

 

[Csi031]

Ok. I'll try disconnecting vacuum pump power tomorrow and let you know.

 

[Csi031]

I'm wondering if the alarm internal battery is flat. So the alarm is not deactivating.

 

[Dec]

It’s possible, but does it have internal batteries, if it has more than 2 wires going into the siren then it would have internal batteries.
See this thread here, car had two immobilisers… http://www.mbclub.co.uk/forums/electronics/206179-c280-w202-wont-fire.html
The immobiliser unit is located in the passenger footwell under a foot rest which is secured by 3 plastic nuts, looks like this… https://www.google.ie/search?q=w202...hUqIcAKHY4bCroQ_AUIBigB#imgrc=jJakjV9OhxrxTM:

Dec