C220 instument failure w202

[Prickleypear]

My Dad's C220's speedo and rev counter recently started playing up, every time the car is switched off and even sometimes after just stopping at a traffic light, the speedo and rev counter(only when switched off) stays on zero, if he hits it on top of the dash everything jumps back to working order.
While the speedo and rev counter are dead, the mileage still runs on, since he's had the car there was no outside temp display, but he put it down to not being fitted on this model, but is starting to doubt now.

I have read somewhere about a relay being at fault but i dont believe this is the case here as the relay wil have to be near to the speedo in order for it to work after being hit.

The car is a C220 W202 from 1995, if any one has any suggestions please feel free to post them up.

 

[Pendragon]

The fact that it springs back to life when bashed sounds to me like it could just be a bad connection.

However it could well be the speed sensor.


Keith

 

[vijilants]

Pop your hand behind the cluster and ensure that the large plug that connects into the back of it has not worked itself loose.

If I remember rightly you can get to the back of it by removing the lower panel in the footwell.

 

[Mr B.]

mine works one min the next it dont could it be the same thing?

 

[Dieselman]

The needles are sticking to the stop pins in the warmer weather.

Remove cluster, scrape paint off pins, refit cluster.

 

[Prickleypear]

Thanks for the suggestions.
I'll try sticking my hand up there and feel for the plug.
I dont think this one has stop pins for the needles, i will have to check but dont think there are any.

Where is the speed sensor located, just in case?

 

[Pendragon]

Sensor usually located on the gearbox.

 

[Prickleypear]

Thanks mate

 

[andy27168]

I,m almost 100% sure Dieselman is on the button as always.
The outside temp display has no relay in it that I know of there is simply a cable from the sensor to the digital display in the cluster.
A faulty sensor can cause a completly blank display like you are describing or an eratic display.
Check you have a sensor fitted behind the L/H side grill insert, remove the insert and the sensor can be clearly seen if fitted, disconnect and clean up spray the plug and the sensor connectors with a decent switch cleaner, as they do corrode, this might spring it into live, failling that replace the sensor, as they were only just over a tenner when I bought mine though that was a few years ago now.

 

[Laters]

I second Dieselmans suggestion that the needles are sticking to the pins. (if the car is prefacelift (which a 1995 car is) it will have the stop pins)
Happened on my old c class. (also a 1995 model)
The speedo would work as it should once it had been moved from the stop pins but once it touched the stop pin it was stuck there till I either hit the dash or went fast enough for it to break free.
I solved mine by putting a small bit of sleeving over all the stop pins.
Easy job once the cluster is removed and the unit seperated from the clear lens.

 

[Prickleypear]

Well Thank you people from MB club.

Over the weekend I took the cover off below the dash but could only reach one of the plugs.
So I pushed the cluster out, both plugs were secure and the earth's seem fine, took off the glass and surely the stop pins were stick, feels like they have grease on them, wiped them clean and so far it seems the problem is solved.

I did this before attempting to check for the temp sensor, it turns out there is no display on the cluster for the temp, just a blanking plug, so i didnt bother to look behind the bumper grill

 

[voy2age]

I,m almost 100% sure Dieselman is on the button as always.

think i'm going to be sick.