Please Help! w124 won't start. Immobiliser Fault?

[thegerman]

Hi everyone!

I'm new to this great forum! I've been enjoying the rather strange experience of driving a rhd w124 for a few months now and the forum has been great help already. Thanks guys!

I haven't found the answer to the problem I've been having for the last few days though:

After coming back from holiday to snow-covered London and not having used the car for 2-3 weeks, I wasn't all too surprised it didn't start. I don't know how old the battery is and I thought it had packed in.

The remote control central locking/alarm worked and the fan and lights on the dashboard came on, but when I turned the key there was complete silence. no noise from the starter, not a klick, nothing.

I thought it might be an immobiliser thing, so I used the little key in the glove box to turn the alarm on and off, but it didn't make a difference.

A friendly neighbour gave us a jump start and the car started instantly as usual.
We drove for about 20min, did some shopping and it started perfectly normal afterwards. In fact, it started perfectly normal another 5ish times that day, mostly doing short runs in town.

The next day, again the car wouldn't start.
I took out the battery and charged it indoors over night.(the light on the charger indicated half full when I plugged it in and full the next morning)

That morning I put the Battery back in and the same as before happened..or not happened: lights and fan all on but not starting, not turning over, no sound at all.

I thought maybe the battery is just dead, so I went to get a new one.

After putting the new battery in, the same problem occurred again. lights and all worked, nothing when turning the key.
I turned the key in the glove box again: off and then back on.
Then the car started as if nothing was ever wrong.

This morning: The same problem. I try to start. Nothing happens. turning the key in the glove box didn't help either this time.
I tried all sorts of combinations of alarm on and off and using the spare key but no success.

This all sounds like an electric problem to me.
Could it be a faulty immobiliser?
Could it be a combination of an flat old battery and an immobiliser issue?
Could I have triggered some sort of security immobilisation when the car was disconnected for over 12hrs?

Is there possibly any sort of reset function for the alarm and immobiliser?

Any advise would be much appreciated! I'm planning to drive to my family in Germany next week and need to have it sorted by then!

Many Thanks!

oh it's a 1993 280TE with 183k on the clock, but runs really well and pulls strong. cheers

 

[thegerman]

I forgot to mention that I tried jump starting it again today after it just wouldn't work with the key, but it also didn't do anything when trying to jump start it!
:-(

 

[carat 3.6]

Welcome to the forum.

It could be the imobiliser, starter, or ignition barrel. You need to test if you are getting power to the starter solinoid, when cranking the car.

 

[thegerman]

Hi! Thanks for the quick reply!

Wouldn't the starter still make some sort of noise? at least a klick?

Unfortunately I don't have the equipment to test the starter solinoid...will have to find out if the AA man would test it I guess.

Thought there might be some sort of sequence to reset the alarm/immobiliser?

Cheers

 

[carat 3.6]

Hi! Thanks for the quick reply!

Wouldn't the starter still make some sort of noise? at least a klick?

Unfortunately I don't have the equipment to test the starter solinoid...will have to find out if the AA man would test it I guess.

Thought there might be some sort of sequence to reset the alarm/immobiliser?

Cheers

Do you know which brand of alarm/imobilser is fitted? Scorpion was a common one. Is there a flashing red led somewhere in the car to show when the alarm is active? If so what dose it do when you try to start the car?

If the starter is not getting power you wont hear anything, you do normaly get a click if it is just a flat battery.

If your car is auto move the lever fron p to n a few times, and then see if it starts.

 

[The G.F.P]

i have had a similar issue and found unless battery is very well charged the immobiliser stays on

i realised this after 3 new batteries and that it only did it when its cold

 

[andy27168]

Hi,
What year is the car?
Have you got red and green leds in the rear view mirror? In the door handle? By the boot lock?
What type of key is it, single button fob with a flick out key blade?
I have a scorpion system which is what from what you have said about turning the system on/off is what you have got, and when my key fob batteries go flat, even though it still operates the locking perfectly ok, I get erratic behaviour from the immobiliser same as you are describing, replace the fob batteries and its back to working ok.

 

[grober]

In many immobiliser set ups of that vintage what happens is that the starter does turn the car over but the engine wont start. The fact that the starter isn't turning the ngine over is an indication there is a problem with the battery /starter motor/ starter wiring. Other possibilities are the ignition switch as has been said or the gear selector linked starter safety switch[ engine will only turn over when in park or neutral did you check this?] I guess there could be a problem with the immobiliser but another possibility is with the OVP [ Feeds the engine ECU] With older cars non starts can be a combination of problems from various components running slightly " below par"--- one on its own may be just OK a couple together may combine to cause a failure to start...However many can be overcome with a good heavy duty battery in a good state of charge. If the battery is several years old I would replace it----- if its younger get the alternator output checked.

 

[thegerman]

Wow thanks for all the replies!

I will try the key fob batteries first as they would be the easiest fix.
I didn't think they would really effect the immobiliser because if the alarm in the glove box is switched off I don't even need to use the fob or even bring it with me to drive the car away...

The Key Fob is not an infa red one so no lights on the door handles.
I don't know if they're called scorpion but the key looks like this:
W124 key fob image by S9KSY on Photobucket

I've tried moving the gear selector around, but hasn't made a difference...might give it another go.

I replaced the battery as a first guess. A brand new Bosch so should be fine.

I have to double check what the little red light does when I try to start...

I hope I answered all your questions.
cheers

 

[thegerman]

Hi,
....and when my key fob batteries go flat, even though it still operates the locking perfectly ok, I get erratic behaviour from the immobiliser same as you are describing, replace the fob batteries and its back to working ok.

My alarm was acting a bit weird before actually...
I've only had the car for about 4 months. when I boiught it the alarm was deactivated with the key in the glove box. I reactivated it and used it without a problem.

The weird thing, though, was when I switched off the engine, left the key in the ignition and sat in the car for a bit, the alarm would go off.
Is that normal?

Also I think when taking the key out but not locking the car within let's say 2 minutes, the alarm would also go off.

Don't know if this is normal, but thought it was a bit odd.
Old car, so I didn't question it

 

[thegerman]

Regarding the key fob again:
It has a switch on the side that slides up or down.
Does anyone know what it does? (just realised the the owner's manual I have is actually older than my car and doesn't even list the 280 or the key fob)

Also there are two buttons and I never worked out what the right one is there for..?
The left one opens and closes it and sets and disarms the alarm.

Any ideas? Haven't found anything on the web about it yet...

 

[tintinmt]

I'm pretty sure that with this Scorpion type immobiliser the 'immobilisation' is simply cutting off the power supply to the starter.

 

[Charles Morgan]

The side button on the remote simply changes the frequency.

If I were you I'd get the immobiliser and alarm disconnected. While it may not be anything to do with the issue, when they start playing up you can have no end of problems.

 

[carat 3.6]

The Key Fob is not an infa red one so no lights on the door handles.
I don't know if they're called scorpion but the key looks like this:
W124 key fob image by S9KSY on Photobucket

We have the same key fob for my brothers car, I'm sure that was a scorpion alarm. The imobiliser did used to cut power to the starter solinoid, I say used to because I ripped it all out after it started playing up.

In your case I would turn the alarm off with the key in the glovebox, then either bypass the imobilser or remove it altogether.

Where are you located?

 

[tintinmt]

I have the installation and operating instructions for the Scorpion 918 which if not the same will be close to yours. I will scan and upload on Monday if you need it. There are a lot of reports of them failing. I have replaced two now with the current model Scorpion alarm SA80 (from memory). There were several places in both cars where the soldered joints had failed. These alarms were fitted at the dealers in the UK prior to sale I believe.
The ECU for the alarm is likely to be under the dashboard on the passenger side. You could probably just bypass the starter motor cut off once you identify the wiring.

 

[bolide]

The switch on the fob turns the interior ultrasonic sensors on and off

Best advice with these dealer-fit alarms, if they give trouble, is to rip them out as Charles says

You may find a couple of non-original fuses near the battery - check those as there may be a fused supply that runs via the alarm system. I have seen this on 190E installs using the same remote keys & red whooper as W124 instals

Nick Froome
www.************

 

[thegerman]

I have the installation and operating instructions for the Scorpion 918 which if not the same will be close to yours. I will scan and upload on Monday if you need it. There are a lot of reports of them failing. I have replaced two now with the current model Scorpion alarm SA80 (from memory). There were several places in both cars where the soldered joints had failed. These alarms were fitted at the dealers in the UK prior to sale I believe.
The ECU for the alarm is likely to be under the dashboard on the passenger side. You could probably just bypass the starter motor cut off once you identify the wiring.

Hi tintinmt,

that would be great! But isn't it a bit too easy to just bypass the immobiliser under the dashboard in the passanger side?
...no wonder the w124 has been leading the car theft statistics in Germany for years!

 

[carat 3.6]

Hi tintinmt,

that would be great! But isn't it a bit too easy to just bypass the immobiliser under the dashboard in the passanger side?
...no wonder the w124 has been leading the car theft statistics in Germany for years!

You dont need to go under the dashboard to bypass it, if you know which wire to live up in the engine bay she's running in 60 seconds!

 

[thegerman]

HEY, I GOT THE CAR RUNNING AGAIN!!!

I tried again and still had the same problem, then tried another simple suggestion from earlier in the thread: I tried to start in N and it worked!!!

So I assumed it just wasn't fully in P and when I had a closer look I found a little sea shell that my girlfriend had found on the beach the other day, that had fallen into the gear selector thingy befrore P!
Bit embarrassing really... but at least I can blame her now

I still want to see if it keeps on working, because it might be a combination of the problems suggested, so tintinmt, it would still be great if you could scan the scorpion instructions for me! Thank you!
Thank you all!!!

 

[Charles Morgan]

Good stuff! No need to shell out on something more expensive!