Help! My Wipers are Possessed!

[Madaboutmx5s]

Took my white roadster out today for the first time in a while and got a strange electrical issue with the wipers. They are coming on automatically.

What I have found is happening:

1. Anywhere below approx 30mph and the wipers stay off.
2. Anywhere between 30mph to 50mph they stay on and also activating windscreen washer bottle (so that's now empty!)
3. After approx 50mph they wipers, etc go off again.
4. Around 2.4k rpm with the engine warm I can simulate the same problem while stationery.
5. As per point 5 problem doesn't seem to happen when engine, etc is cold??

Any ideas?? I changed my steering wheel and boss recently so thought it maybe that but taking that off and problem still remains.

Any help would be appreciated. Done a search on here and google but not come up with anything.

[BlitzWing]

earth issue? fuse or relay starting to fail? long shot I know but maybe something is shorting. That or you need to wash your car with holy water.

[Madaboutmx5s]

earth issue? fuse or relay starting to fail? long shot I know but maybe something is shorting. That or you need to wash your car with holy water.

Thanks for your advice. Only thing I did try playing with this afternoon before having to leave it was one of the earth points to the windscreen motor. Took it out and out it back in and wipers then stayed on all the time. Played with how tight I toured it and they went off. However then when I practiced reving the car when warm at 2.4k rpm the wipers came back on again automatically.

Don't want to buy secondhand parts unnecessarily and looking the wipers are on a fuse so guess if the 20amp fuse for the wiper was duff it would just stop working? Wondering if a windscreen wiper motor or washer bottle pump could go back and cause these symptoms or if like you say I've a bad earth somewhere?

[kung fu jesus]

I would bet it is in the switch. You could take off the combo switch, disassemble it, look for a worn or broken detent or corrosion.

[Madaboutmx5s]

I would bet it is in the switch. You could take off the combo switch, disassemble it, look for a worn or broken detent or corrosion.

Thanks. When you mean on the switch do you mean the wiper stalk mechanism?

[kung fu jesus]

Yes.

[Golden Stallion]

Yes.
Just thinking here, how does that effect the car when warm. Do you think it is a coincidence or something

[kung fu jesus]

It seems like a resonance issue with a worn or failing switch or circuit. NVH can change as the car comes to temperature. I am guessing the vibration the car makes at the described speeds or conditions is the clue.

[Golden Stallion]

OK not doubting the great kfj or anything, just wondering

[kung fu jesus]

I could be totally wrong, and checking the ground would be the first option. I have seen this sort of thing before in older cars of other makes.

Remember, there are no bad questions here. :)

[Agent☣Orange]

I'm questioning the stalk switch also. We know the wiper motor works so that's not the problem. What's left is the signal. Yes it's weird that messing with the ground and vibrations at certain RPMs sets it in motion but once you've ruled out motor and ground, all that's left is the switch IMO. I wouldn't just check the wiper motor ground but all the grounds in the engine bay and the switch.

Let us know what you find though because we want to know.

[Golden Stallion]

Well it makes since now that you say my from car vibration as our engine are not what I would call smooth:|

[Agent☣Orange]

It's a possibility. The NB flasher module is another device that fails from vibration causing the solder joints to dislodge. Older Miatas can suffer through similar symptoms or corroded ground points.

[theothersawyer]

This reminds me of a time I was getting a ride in a friends FC RX7 and we were getting onto the highway and once we hit 140mph, the wipers just started going!

[Madaboutmx5s]

Thanks KFJ I am away for a few days with work but have a spare indicator/wiper stalk mechs so will try this.

[kung fu jesus]

Good luck!

[Madaboutmx5s]

Thanks all for the advice on this and a update so if anyone has something similar may save a bit of time if they are searching for a result. I had a play around with this before going away with work for a few days. Tried a spare different indicator stalk mech and this didn't make any difference. I then figured (Homer Simpson light bulb moment) that when the wipers were going off to begin with washer bottle was activity and drained washer bottle so this was likely the culprit and not the wiper motor/mech. Had a play around with the connections to the after market washer pump motor and (touch wood) this seems to have cured it for now as used the car for around 30 minutes today getting it warm and it didn't happen again.