Dashboard / Instruments again

[Grahamcol]

Thanks to those who responded to my query last week but I would like some further advice.

On my 2000 W202 C280, most of the dashboard warning lights will light up momentarily on turning the ignition key to pos.2 and then extinguish prior to starting the engine. I understand these lights should stay on until the engine has started so there appears to be a fault. However, I'm uncertain whether it's a fault in the instrument cluster which causes this (as my indie has indicated) or whether the fault is being caused by something else.

Anyone got any ideas as I don't want to have a new cluster fitted and find the problem is still there ?

 

[recycled]

not all will stay on. the srs goes off first. the ones that wait till the engine comes on, should be oil/ coolant/ battery/parkingbrake/abs.
brake off when you operate the handle

 

[television]

The instrument cluster has to be told what to do by other components like the ignition switch, and the fault could just as well be there

 

[Grahamcol]

Thanks. In this case my indie may well be getting things wrong by telling me just to get the cluster renewed.

What would be the best way of establishing exactly what's causing the problem ? Someone with specialist knowledge of the electrics / electronics systems of the W202 I guess. Surely that's the indie again then ? Does anyone know of someone in the West Midlands who can accurately diagnose and resolve the problem please ?

 

[Diesel Benz]

I'm a bit lost with the lights that are supposed to stay on but do not, in your car. To me it looks pretty likely that there is nothing wrong. Which indicators do you see should stay on? My car would not have a red (or any colour) oil pressure warning light or alternator light that traditionally go off only after the engine is started, I don't think I have any indicator on for more than the short time to see that the indicator bulbs are working (but I did not go to the car and check, these things are difficult to remember in detail).

 

[Grahamcol]

Most warning lights should stay on I believe. examples are oil, alternator, but in particular the ABS which I understand is part of the mot. My ABS goes off after about half a second (along with nearly all other warning lights) BEFORE the engine is started although the ABS / other lights will light up if there is a genuine fault - my post last week gives full details.

As I said, i'm mostly concerned that at the next MOT there might be a problem of the ABS light not following the correct sequence although it doesn't come on with the engine running.

 

[television]

I cant see a problem with the MOT the lamp is on with the ignition and goes off when its running, I know that there is a X second countdown for this, but I doubt if that will be picked up.

Working out why it does it is harder

 

[GRAV888]

I cant see a problem with the MOT the lamp is on with the ignition and goes off when its running, I know that there is a X second countdown for this, but I doubt if that will be picked up.

I bet you it will if it is not working correctly.
They are getting very strict on ABS lights now. Both of mine (2 cars) go out around 1.5 seconds after switching the ignition on.

 

[fredfloggle]

I cant see a problem with the MOT the lamp is on with the ignition and goes off when its running, I know that there is a X second countdown for this, but I doubt if that will be picked up.

Working out why it does it is harder

Nothing that a 555 won't put right.

 

[recycled]

The car will fail if the ABS lights do not go off after the engine starts.
Now if they go off before the engine starts is another matter.
Just tell the tester it is a special edition.
diesel benz yours is newer model., but in the w202 the lights do come on.

 

[television]

This has to be a fault on the ignition switch, there is nothing else.

These switches fail on the 129 and on diesel 210s mainly due to the high loading.

Turn the key very very slowly to see if the lights go out before the starter engages, if they do turn the switch back and see if they come on again.

If this is the case, then the switch needs replacing, a few brave ones take them apart and adjust the contacts

 

[Grahamcol]

Thanks Malcolm,

I will try this and report back next week (going away for a few days now).

I think I'm right to question whether it really is the instrument panel because my view is it could be something else causing the problem (like your suggestion i.e. the ignition switch)

 

[Diesel Benz]

I made a trip to my garage, I knew the indicator lights would come on but to my surprise, hardly any went off before I started the engine.

Note that the 202 also has an engine oil level warning lamp, not an oil pressure warning lamp (it could be combined, don't know how it warns about oil pressure, if it does), according to the workshop documentation (I did not find a user manual). Even this light could have gone away before the engine was started. I believe not even the SRS light went off from my W221 before the engine was started.

Malcolm's description about the ignition switch operation was interesting learning too.

 

[recycled]

the srs light should go off. it does not need to run before your airbags are fired. only needs to key to the on position.your abs ,engine needs to be running for it to function. as does your alternator and related functions

 

[television]

I made a trip to my garage, I knew the indicator lights would come on but to my surprise, hardly any went off before I started the engine.

Note that the 202 also has an engine oil level warning lamp, not an oil pressure warning lamp (it could be combined, don't know how it warns about oil pressure, if it does), according to the workshop documentation (I did not find a user manual). Even this light could have gone away before the engine was started. I believe not even the SRS light went off from my W221 before the engine was started.

Malcolm's description about the ignition switch operation was interesting learning too.

There is no oil pressure lamp on these engines, I looked it up yesterday

 

[television]

Thanks Malcolm,

I will try this and report back next week (going away for a few days now).

I think I'm right to question whether it really is the instrument panel because my view is it could be something else causing the problem (like your suggestion i.e. the ignition switch)

The instrument cluster has nothing in it that could blank it all, it is fed from the switch.

I have known about 15 of these switch faults, mainly it affects the wipers, and heated rear window,or the engine cutting out, on diesel cars the extra loading comes from the glow plug circuitry

 

[Diesel Benz]

the srs light should go off. it does not need to run before your airbags are fired. only needs to key to the on position.your abs ,engine needs to be running for it to function. as does your alternator and related functions

A bit off topic as this is about the W221 but I had another visit to my garage, the SRS light comes on when I switch ignition to the first position, and goes out after a short time. If I then turn ignition to the second position, the SRS light comes on again, and stays on with all other warning lights (actually most are on the LCD display) until I start the engine. It actually sounds reasonable that all lights stay on at the "check lamps" period.

A different thing if the "check lamps period" could be a few seconds or as long as the engine is started. Anyway, if the W202 is supposed to behave like the W221, then I'm changing my opinion and assuming that this W202 car might have some sort of an issue (probably what Malcolm explained) but I would still assume no problem at car inspection (although of course I don't know the UK local rules and interpretations).

 

[Grahamcol]

Well, I tried what was suggested about turning the ignition switch on slowly and then backing off very slowly but still the same so I really am at a complete loss to know what's causing the fault with the warning lights.

 

[television]

Well, I tried what was suggested about turning the ignition switch on slowly and then backing off very slowly but still the same so I really am at a complete loss to know what's causing the fault with the warning lights.

If it did the same thing then surely that must show that it is the switch.

If you turn the switch to a point where the dash goes out, then turn it back and they come on, that must be the switch.

Turn your wipers on before you start the car if they stop at the same time as the dash ==== switch

 

[Grahamcol]

Hi Malcolm,

Sorry, I've not explained myself very well.

What's happening is that I turn the key to the point where the lights come on (for a split second) and then turn back but they don't come back on until the key is turned forward again and then only for a split second once more. i.e. the lights will only ever come on for a split second and they will never stay on.

I'm not saying it isn't the ignition switch, I just don't know. I wouldn't have thought the ignition switch has any kind of timer built in to keep the lights on for x seconds. If I could establish what is supposed to keep these lights on for x seconds then I would at least have some idea where the fault lies.