mikevernon@talktalk.net

My C4 has been laid up for some months and is now exhibiting some bizarre electrical problems.

With the ignition key switched on, the front and rear wipers operate continuously. Turning off the switches makes no difference, except that I can make the front wipers run at normal speed or high speed. The only way I can turn them off is to turn off the ignition or to remove fuses 24 and 28.

Sometimes, but not always, the heater blower in the engine compartment turns on and off at regular intervals of around 4 or 5 seconds. It does this even after the ignition is switched off. This is controlled by the same fuse as the rear screenwiper

The car has been outside over the winter so has got fairly damp in the engine and luggage compartments. I suspected a damp relay so I've taken the lid off the fuse/relay box and dried it out, but it hasn't cured the problem. The engine does start and run normally.

Any ideas?

stevepaa

Pop out your fuel gauge and then pop out the rear wiper switch and disconnect it. Use ohmmeter to check it. It should be normally off.

jimq

some mice maybe chewed on some wires? Oh yea welcome on your first post and show us some pictures
Having your email as your name could mean more spam then you can imagine!

mikevernon@talktalk.net

Stevepaa. A faulty rear screenwiper switch wouldn't explain why the front wipers are also running. I need to look for some part of the circuit which could be supplying power to both front and rear wipers.
I still suspect something in the main fuse/relay box because it was very damp inside there.

Where can I get hold of a wiring diagram?

Jim. Thanks for your welcome. You could be right about the spam thing.

Mike

stevepaa

I can send you a pic tonight. What year car?

mikevernon@talktalk.net

Steve
Many thanks for that. My car is a 1990 C4, although I imagine that the wiper circuit is the same for all years.
I haven't yet identified which relay controls the front wipers and I don't know whether the same one supplies power to the rear wiper. If it does then that sounds like the probable culprit.

stevepaa

The rear wiper has an integral relay in it. I have sent you pdf files. I think you had a mouse attack your harness. That is the ony place these wires all mingle.

stevepaa

Any update?

toxtethogrady

Hope its ok to resurrect such an old thread, I have EXACTLY the same symptoms as the OP and wondered whether anyone had any suggestions.

To sum up: 1990 964 C2 , UK car
Has been stored outside but under a (supposedly) breathable cover last few months.
Initially front and rear wipers both run as soon as ignition turned on. Can switch between fast and slow speed but not turn off.
I also have the intermittent turning on and off of the front blowers - they come on for around 2 secnds then turn off again then repeat.
Car starts and drives fine but wipers run continuously.

I also found that there was significant moisture in the fuse/relay box - dried it out as thoroughly as I can - there was lots of moisture under the wiper relay so i ssumed this was probably the issue, but so far it hasn't changed - do you think the relay is worth replacing ?

The point made in the thread above about vermin is certainly possible and one I have consdered but it seems a huge coincidence that the OP had exactly the same combination of symptoms - mice chewing would presumably be random in effect, so I'm thinking there is a specific component failure responsible.

Grateful for any / all help received.

Steve

jimq

can you pull the cover off the relay and see if it wet or corroded inside?

toxtethogrady

Thanks for the reply, I think it certainly could be , the whole fuse box was very moist and there was a patch if damp right under that particular relay.
I'll try and take the cover off tomorrow and see - I didnt know it was possible to get thhe cover off. Will report back tomorrow