Immobiliser fault (red&green LEDs flash alternatively)

[BWDuncan]

Hi all,

Still getting used to my new pride and joy and to the forums... I've tried searching for this problem but can't find a solution. I'm sure lots of people have seen this before.

I can unlock and lock with the key IR remote and the engine will start if I'm quick enough (usually not if I decide to glow it twice). Sometimes when I get the key to position 2 and I'm waiting for the glow light to go out the lights on the mirror flash red and green alternately. I lock and unlock with the key and the engine starts fine.

Googling suggests that I should replace the batteries in the key fob, however the book says that to test the batteries I should press and hold the button and if it flashes red once the batteries are fine. It does, so I'm not inclined to think that this will fix it. Other sources suggest disconnecting the car battery for a few minutes to a day, but I live in irrational fear that this will cause more problems than it will solve!

Any ideas?

I also only have one key so if anyone knows of a dealer in Scotland who will do a duplicate for a reasonable I'd love to hear about it.

Thanks,
Bruce

 

[Nik_Endeavour]

Try in this order. It will not cause any problems (apart from spending a 10-nner)

1. Replace batteries (remote)
2. Disconnect and reconnect battery


Shouldn't do it again

 

[jasonyw]

Hi all,

Still getting used to my new pride and joy and to the forums... I've tried searching for this problem but can't find a solution. I'm sure lots of people have seen this before.

I can unlock and lock with the key IR remote and the engine will start if I'm quick enough (usually not if I decide to glow it twice). Sometimes when I get the key to position 2 and I'm waiting for the glow light to go out the lights on the mirror flash red and green alternately. I lock and unlock with the key and the engine starts fine.

Googling suggests that I should replace the batteries in the key fob, however the book says that to test the batteries I should press and hold the button and if it flashes red once the batteries are fine. It does, so I'm not inclined to think that this will fix it. Other sources suggest disconnecting the car battery for a few minutes to a day, but I live in irrational fear that this will cause more problems than it will solve!

Any ideas?

I also only have one key so if anyone knows of a dealer in Scotland who will do a duplicate for a reasonable I'd love to hear about it.

Thanks,
Bruce

It telling you the fob batteries is below 3V, use an avometer to ascertain and if it still OK then you need to sync the fob with the security system. See owner book.

 

[lukejr]

I have the same problem. W202 1995 C200 with one button with flip out key, no alarm in the car.

Last Thursday I got the red green alternative flashing lights on the rear view mirror. Car would not start tried lots of things, but left and next morning it worked. Car drove fine, that evening, when I went to start again I got the flashing lights on mirror.

Could not get it to start did everything, changed key batteries, disconnected car battery, hooked up car battery charger unit, tried second key set.. Lock and unlocked 100s of times, no difference. Each time I turn key in ignition the alternative red green lights flash on mirror. Had to have car towed home.

Anyone have any suggestions. How does the key system work in the 1995 model (different to 1997+ model). Does the key button unlock car and disable the immobilizer at the same time? Or does the key deactivate the immobilizer when key is in ignition?

Thanks in advance.

 

[bennesspipers]

Hi,new keys are about £180 at the last check ! Sounds to me like you've both got bad or broken connections in your key fobs. The fob button unlocks & unimmobilises all in 1 go. You both ought to check that your metal key blade will manually unlock the passenger door & boot ('cos they seize up) because if they wont & you get a flat battery you've got an even bigger problem, Also, look at 'W202 starting problems' on here.

 

[bennesspipers]

Also, look at 'Key fob trouble' on here, & if your door lock wont manually unlock, look up 'door lock'.

 

[lukejr]

Thanks for the reply. Yeah it opens the door manually, and by using the fob. LED on rear view mirror flash red when locking and green when opening.

Once key is turned in ignition it starts flashing crazy alternative red and green. I assumed that once it unlocked with the fob that also disabled the immobilizer.

Will have another look around the forum thanks again for help and reply.

 

[Dec]

Do you also have a Red and Green LEDs in drivers door handle, you may not notice them if the car is new to you.

Dec

 

[Alps]

if the leds are in the rear view mirror, then its a diode thats in there that needs replacing. it happened to mine 5 or so years back, my indi sorted it saying it was a common problem. try disconnecting the rear view mirro and see if it sorts it.

 

[lukejr]

The lights in the drivers door handle flash red green too when I try and start the car.

Need to sort out how to get it to a garage tomorrow.

 

[Dec]

When you lock, the Red only flash and the immobilizer is enabled, car won’t start.
When you unlock, the Green only flash and the immobilizer is disabled, car will start.

After you unlock and you turn the key in the ignition to position 2, ignition on, (position 3 being start) if the Red and Green flash alternately… Red/Green/Red/Green etc… this means that the immobilizer hasn’t been disabled and so the car won’t start.
The reason the car wont start is because the immobilizer hasn’t been disabled, so either the batteries are weak or there is some issue with the immobilizer or it has to do with what Alps says above.

As far as I know, just because the doors unlock with the key fob doesn’t mean the immobilizer has also disengaged… because of weak or poorly connected batteries.

Also try this;
Sit in car
Press keyfob button twice
Put key in ignition WITHIN 30 seconds and turn to position 2 wait a few seconds and try to start car.

Dec

 

[andy27168]

As Dec, DO NOT assume the fob batteries are ok because it operates the central locking.
Some 202's had a separate immobilser operated by the fob (normally fitted to cars with CAT A/1 Scorpion security system), others cars had a proximity chip in the key and when the key was put in the ignition the chip was close enough to the collar of the ignition switch, switching off the immobilser, though i have no personnal experience of this type it is quite common for the ID tag in the fob to come loose and not be close enough to the collar to activate the immobilser.
If you take a pic of the ignition switch i maybe able to identify which immobilser system you have but i suspect the fact you say you have no alarm that it will be the chip in the fob type, are you sure that there is no alarm fitted? have you any movement sensors on the "A" pillers, or siren under the bonnet adjacent to the radiator on the N/S?

 

[lukejr]

Cool Dec, thanks for photos and the camera trick to check. Just did it with camera and a light light flashes on click, and red light too when fob button is held. I changed the batteries in the fob too, but no luck.

Andy, thanks for suggestion. No alarm fitted, no sensors in car. I will take a pic of the ignition and post here within an hour.

Thanks again to everyone for helping.

Luke

 

[Dec]

As Dec, DO NOT assume the fob batteries are ok because it operates the central locking.

I learned that from you Andy, I think Lukes car is too early for the collar/ignition thing.

Luke, did you try;
Also try this;
Sit in car
Press keyfob button twice
Put key in ignition WITHIN 30 seconds and turn to position 2 wait a few seconds and try to start car.

Dec

 

[lukejr]

On advice from local garage I disconnected the car battery. Now the boot will not open manually with the key, the lock just won't turn. So I'm stuck with a car with no power, and no way to get at the battery to connect back up. Have WD40 the lock but will not move at all, no give, have tried both keys. I'm guessing the boot lock hasn't been turned in 14 years! I never used it the past few years anyway.

The keys manually open the passenger side door, so I can get access to the car and and pop the bonnet, but no way to open the boot to re-connect the battery.

Thanks Dec, I tried that yesterday (when battery was connected) no luck. I think it's time to pay the money and get it towed to garage and see if they can fix it and at least get into the boot.

I'll post the photo of the ignition in a minute so you might be able to let me know what type it is. Thanks again for the help.

 

[lukejr]

Attached is a photo of my ignition, if you need any further details let me know. Thanks again guys.

 

[Nibbo]

On advice from local garage I disconnected the car battery. Now the boot will not open manually with the key, the lock just won't turn. So I'm stuck with a car with no power, and no way to get at the battery to connect back up.

Ooops, someone should have read post #5 a bit more carefully.

 

[lukejr]

Indeed, but I had it disconnected before reading it. Too late now anyway.

 

[Dec]

Your lock is seized due to lack of use.

Get the WD40 straw into the lock key hole as far as it will go
Flood the lock with a 5 second burst of oil
If you can’t get key into lock, use an opened out hairpin and wiggle it up/down
Repeat every 10 minutes
The lock will eventually open by key, don’t force, it could take hours or days but it will open.

Dec

 

[lukejr]

Will do Dec, I'll keep flooding it with WD40. The key will pop in so will wiggle a lot.

Thanks.