The wiper fuse blew on my Toyota Camry wagon when I activated the rear wiper. I've taken the motor off and looked inside - no obvious problems. I'm wondering what electrical testing I can do with an ohmmeter. The complication is the relay unit, which has six connections. I'm not sure how it operates.
How many connections to the motor unit? See if you can find the electrical diagrams on the 'net. Does the rear wiper doe "clever" things like come on automagically when you go into reverse and the main wipers are on? That could explain the number of wires to the relay box, though I'd expect that sort of thing to be done by a BCU these days.
Most rear wipers have an intermittent setting. Maybe also a timed cycle when using the washer, if it has one. So the 'relay' unit would have connections to the switch as well as the motor. The timer unit on my SD1 which has both these functions has 6 connections.
But what you need is a circuit diagram for your model. You could then test the motor directly from the battery to ascertain whether it's that or the timer causing the problem. Was there any smell of burning when you looked at the motor?
On mine the rear wiper was so tight to turn because of corrosion between alloy housing and steel shaft going to wiper arm, stripped it completely and cleaned up and greased, goes much quicker now than it ever did. Al
I have a kind of generic circuit diagram, which doesn't convey a great deal to me. I think you're right about the timer. I tested the motor directly on the battery. Initially there were big sparks (the fuse-blowing kind), then it went open circuit. Not a good sign. I think I may need a new wiper motor.
While testing things I noticed my battery voltage was very high (I'd just been running the engine). With the engine running the charging voltage is about 19v. A new, probably more serious, problem. It's a bit of a coincidence, so I'm wondering if they are linked. Could the high battery voltage have caused the motor to fail? I'm familiar with low or no voltage from the alternator, but I don't know what can cause a high voltage.
Buggered regulator innit? Which translates as new alternator time.
If you've got 19v in your car, time to sort it and fast
I am not starting the engine again until it's fixed. I hope it hasn't caused other damage already.
You also have to watch these "tyre" places. I forget the details (it's been quite a while) but I had a voltage problem. They 'bunged' on 12V and zilch, so they 'bunged on' 24V (before I could stop them). Fortunately still zilch else I may have had every piece of equipment in the camper shagged. I can't remember what the problem was. I think I lost 1 x 12v bulb. Bloody kids who don't care a shit.
Assuming your DVM hasn't failed - it is reading some 12.5v from the battery with the engine stopped? - the alternator regulator has failed. This is usually internal to the alternator but can be replaced for about £30 if you can be bothered finding one.
Unless the rear wiper was in use for a long period, it's unlikely this high voltage will have caused it to fail.
There are a couple of things going on here that I don't understand. After sitting overnight the battery still reads 18v, engine not started. This shows on three different scales of the DVM. Not believing it, I checked with my old analog meter - same thing. How can a 12v battery hold 18v of charge?
Never seen any battery that reads that much over its nominal voltage. Try disconnecting it and see what it reads. And switch on the headlights etc without the engine running and see what the reading is.
Because it's grossly over-charged, plus there's a surface charge on top of that. Normally, the max you'd see going into it would be 14.8V (which is at the top of the charging range for calcium batteries).You could try bringing it down with a load, like an old headlamp, but don't even switch the ignition on until it's come down by at least 3 volts.
are there not some strange new batteries that do in fact take higher charge? it might also be pure 'surface charge'. If the battery type has that effect..
More interesting battery behaviour. After another day I checked the voltage - still at 17.8v. It doesn't seem a good idea to leave it at this level, so I turned the headlights on. The voltage dropped steadily to about 12.8, then rose again to 13.7, then slowly fell again. After about 10 minutes it was down to 10.3. I turned the lights off, and it came back up to about 14.5v. I've now put the interior lights on, with the aim of slowly pulling the voltage down to about 13 v. This was a fairly young battery, but I guess it may be buggered by now. When I have some spare time I'll probably pull the alternator and have a look at the regulator - I usually can't resist getting involved in time-wasters like this.
It sounds like the battery is knackered. It should run the headlights (2) for at least a couple of hours without going much below 12 volts.
If you decide to have a go at fixing the alternator, check you can buy a new reg for it. Find out the make and model (should be on the body somewhere) and if a common type Ebay should have them.
What's wrong with popliteal fossa?
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