W124 Headlight wiper motor blew a fuse

[blondebier]

Hi Guys,

The headlight wiper on the passenger side doesn't work on my car. I bought a replacement motor on eBay. (It was a used part.)

On Saturday, I took the headlight out and put it in.

When I tried the wipers, the electric warning light came on on the dash immediately and number 3 fuse blew. I replaced the fuse with another white 8A and tried it again. It blew again.

I ran out of time, so put the old motor back and tried it again. It didn't blow this time, but I am obviously back to square one.

Is it likely to be a duff motor or something worse?

What would be the easiest way to test it?

Any tips would be helpful.

Cheers,

Blondebier

 

[Frank O' Phile]

You can test these with a 12v supply. Except I can't remember the wiring polarity. Sorry.

When I found a couple of motors I found that one side has 3 wires and the other, 4. Which one do you have?

 

[blondebier]

Mine have 3 pins. So would it be ok to connect it straight to the battery?

 

[Druk]

Mine have 3 pins. So would it be ok to connect it straight to the battery?

I wouldn't do that. If there is an internal short you will burn out the wire you're using to test. The fuses are blowing for a reason (stating the bleeding obvious...sorry). Corrosion in the bushes on the output shaft is the usual cause of these failing.

 

[Ian B Walker]

Also worth noting. The left hand motor has three pins, the right (drivers side) has four.

 

[SilverSaloon]

you can take these motors to bits and grease and often they work again

 

[blondebier]

Thanks for the replies guys.

I'll take the replacement one apart and see if it is repairable.

It looks like Mercedes took a bosch part and stamped a hot marker into it to impress their logo and part number...

I wander if you can buy the internals for these from Bosch and recondition them. Even the £80 price tag from Euro car parts seems a bit steep...

I'll see what Google throws up.

 

[SilverSaloon]

I'd say with 99% confidence the large cog inside will be sized. Remove the back with a flat bladed screwdriver and pull off the cog. Then connect it up and see if the motor spins. If it does, grease it all and put it all back together. You may also want to clean up the other smaller cogs aswell.

Make note of the position of the cog to the rack before you start removing bits as that denotes where the wiper position returns to.

good luck.

i think the trick is to purposly switch on the lights and spray them every month throughout the year (mainly got to remember in the summer when you might not use your headlamps for months on end), otherwise time the winter comes and you ahve the lights they will be siezed.

 

[blondebier]

Thanks SilverSaloon, I'll give it a go.