A-Class Electric Double Whammy!

[Richard Murray]

Hi

My wife's A-Class, 168 model, 1.6 petrol injection with 75,000 miles on the clock (1999) isn't working properly. Two problems which I assume are completely unrelated both started yesterday.

Major one - it won't start. Ran fine yesterday. Has full service history by MB from 51,000 with remainder by myself. I used it yesterday so can't understand why it has suddenly developed this fault. When you turn the ignition - the engine just ticks and the interior lights flash. The dials on the dash display START ERROR. MB dealer won't say anything unless I can take it in!!! I suspect starter motor is goosed. I phoned a mechanic (local garage) who said to rule out a couple of things first - such as...

1/ Getting spark
2/ Getting fuel
3/ Immobiliser

Getting the spark plugs off is a pain. They're located under the car at the bottom of the engine block, and have allen-bolts securing the ignition unit (or whatever it is) in place. The plugs themselves were changed under a 1,000 miles ago. Regards the fuel - it's got 3/4 of a tank and I can hear the fuel pump prime itself when you turn to stage 2 of the ignition with the key. Regards the immobiliser, I'm sure it's not related. The key fob has a new battery, and the immobiliser should disable at stage 2 of ignition according to the handbook. I've also tried locking and unlocking to reset the system.

The mechanic also suggested if it was the starter motor - then to tap it with a hammer to see if the selenoid had stuck? That's if I could find it! Apparently, if I rock the car forward in gear it could disengage it? Tried this, but nothing. I've thought if I could jump-start it - then I could say for definate that the starter motor is to blame. Unit is £165 from Bosch (European Car Parts)! Not sure what MB genuine part would cost? How easy is it to fit? I couldn't even find the starter motor - which I assume is under driver's footwell area. A-Class is a pain to work on anyway - with space restrictions. Leave for the professional with hydraulic ramps?

The other problem is the rear wiper won't go off. Usually the button on the central dash needs one press to deactivate, but it just keeps on wiping? I've now disconnected the lead to the wiper as it will damage the glass otherwise.

Any views greatly appreciated.

Thanks

Richard

 

[bundy]

it sounds very much like a low voltage fault (flat battery)
if the voltage is low the relay used in the wiper circuit might not respond. so keeping the switch on. i assume the engine is not turning over but the starter relay is clicking!!!

regards ted

 

[MondeoMan]

I'd agree that it sounds like a flat battery, are the headlamps dim?

I'm not sure your mechanic is any good - there's no point in checking for a spark or fuel if the starter isn't turning over the engine!

 

[Richard Murray]

Sorted!

Thanks for the feedback. You were right about the battery. Garage dignosed straight away after I dropped it off. Must admit - I felt it was a starter problem. Looks like the original Mercedes battery - so given the car is a 1999 model - it was probably due for replacement anyway. The wiper is still wiping - so I've disconnected again. Could it be a relay?

Thanks

Richard

 

[television]

MB class your fault as S4 that is the combination switch itself.

Malcolm.

NB if you do want to do it yourself you have to remove the steering wheel,etc If you want the info Please ask.

Malcolm

 

[Richard Murray]

Combination Switch Replacement

MB class your fault as S4 that is the combination switch itself.

Malcolm.

NB if you do want to do it yourself you have to remove the steering wheel,etc If you want the info Please ask.

Malcolm

I'd appreciate instructions for this, thankyou.

Richard

 

[television]

Disconnect battery, wait 15 mins
Unscrew 2 bolts,one each side of steering wheel
lift air bag off and remove connector
Place air bag with expulsion area on top.

front wheels ahead, detent engaged
take out center screw
remove steering wheel
remove 2 screws and remove fanfare horn and air bag clock spring from the jacket tube
separate horn cables
remove steering wheel

undo 2 srews in center, when putting back shorter one on the right
The combination swich diconnects when you unplug it

I do stress that this is a recognised fault, I too can see no other reason other than switch S4.

Malcolm

 

[Richard Murray]

Steering wheel removal

Thanks for information. I assume from your description that 'switch S4' is located under the steering wheel and not situated on the central dash? It's an electronic relay switch and not the actual function switch?

With the battery disconnected (allowing 15 minutes) is it perfectly safe to disconnect the airbag - no other points to watch?

Also - what does 'detent engaged' mean?

Richard

 

[television]

Thanks for information. I assume from your description that 'switch S4' is located under the steering wheel and not situated on the central dash? It's an electronic relay switch and not the actual function switch?

With the battery disconnected (allowing 15 minutes) is it perfectly safe to disconnect the airbag - no other points to watch?

Also - what does 'detent engaged' mean?

Richard

the one I have have given details for is the car with the switch on the side of the steering column, if yours is not there I need more car details
S4 is the actual switch, this is the only fault in the MB data base, the contacts short together.
Detent is the steering lock.

Malcolm

 

[Richard Murray]

Wiper Switch

It's the rear wiper. The switch for this is located on the central instrument column between passenger and driver, above the CD/radio, etc. At the moment - I've disconnected it at the motor on the tailgate after removing trim, etc.

Thw wiper switches itself off when the tailgate is raised, but as soon as it get to a lowered position (no quite shut) it starts up again. Normally the wiper can be switched off if you press the button up. If you press the button down - then it engages the wash/wipe (three strokes) and then intermittent wipe thereafter. Press button up once again and it should cancel, but it doesn't.

 

[television]

It's the rear wiper. The switch for this is located on the central instrument column between passenger and driver, above the CD/radio, etc. At the moment - I've disconnected it at the motor on the tailgate after removing trim, etc.

Thw wiper switches itself off when the tailgate is raised, but as soon as it get to a lowered position (no quite shut) it starts up again. Normally the wiper can be switched off if you press the button up. If you press the button down - then it engages the wash/wipe (three strokes) and then intermittent wipe thereafter. Press button up once again and it should cancel, but it doesn't.

The little word rear makes a huge difference, I missed it,ignore the other info
I will come back later

Malcolm