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Old 26th February 2015, 20:14   #11
Mdean22
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Quote:
Originally Posted by SD1too View Post
Thanks Russ for endorsing my suggestion at post no. 3. It seems to have fallen on deaf ears though ....

Simon
Sorry simon, no it hasn't its on my jobs to look at. Will check this weekend, now I'm sure my cars haunted or something, I decided to take it for its MOT knowing it would fail on the wiper issue, I suspected there may be other faults to rectify so would have a list to work off. i told the chap I had disconnected the wipers because they wouldn't stop, I reconnected them and they worked fine, I drove off with a full Mot with no advisories, happy days. 5 minutes from home the wipers started again and wouldn't turn off.
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Old 26th February 2015, 20:24   #12
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And to top it off, I went to my nans all happy the car had passed and fixed it self. When returning to the car it wouldn't engage gear, the auto gear selector bolt on the gear box had come loose and wasn't connected to the gear selector on the gear box. I had no tools so had to manually engage gear by lying on the floor and limp the car home. It's a real love hate relationship me and my car are developing.
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Old 27th February 2015, 14:35   #13
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Thanks guys there's a issues somewhere under the fuse box, don't know where yet but will do some digging this weekend. Will try get some pictures when I find where it is for future reference.
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Old 24th January 2020, 16:26   #14
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So what was it?!!
How did you fix it?!!!

Another time waster!
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Old 24th January 2020, 23:54   #15
Mike Noc
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It was 5 years ago Moorsey, and he hasn't posted anything for well over a year, so I'd be surprised if you get an answer.
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Old 25th January 2020, 18:01   #16
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Quote:
Originally Posted by HarryM1BYT View Post
My take on this, is that the wipers can be controlled by either the BCU or directly by the stalk switch.

Either source could be forcing the wiper relays on and the wipers to run.

He suggests he has unplugged the wiper stalk, so that only leaves the BCU generating the 'run' signal, or a fault on the wiring.

He might try unplugging the BCU, after disconnecting the battery, then reconnecting the battery to see what the result is.
According to Haynes's circuit diagram of the wiper switch, the wiper switch sends signals to the BCU exclusively, and only the BCU controls the 2 wiper relays. These signals to the BCU are very low currents, and are, as such, susceptible to dirt and damp issues.

The only slight complication is that the washer switch ALSO directly powers the 2 wire washer pump by grounding one connection of the pump. The wiper connections generally stay within the cabin, avoiding road dirt issues.

However the washer pump connection extends to the washer bottle, which is in one of the most exposed areas of the car to dirt, just behind the front bumper. This makes the washer switch connection to the BCU very susceptible to dirt and damp issues, causing false activation of the wipers, while NOT activating the washer pump.

To summarize, a small amount of dirt and damp on the washer pump connection exposed behind the front bumper, CAN cause the wipers to operate uncommanded, while having NO other symptoms or effects. Be aware, if your wipers run uncommanded.

On a new point, one of the advantages of the design of the R75, is that under most circumstances, loads are switched by "intelligent" switches, that helps to protect the load under abnormal situations, prolonging the life of the electrics, and our cars.

The washer pump is a rare exception, being protected by only a 5A fuse (F9).

I must get a better circuit diagram than Haynes.

Last edited by MarkS; 25th January 2020 at 18:34.. Reason: Another reason why wipers may run uncommanded
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