Widscreen wiper motor testing

green A8 · #1 28th December 2012, 05:36 PM

As I stated in my intro post I've bought a badly neglected and somewhat damp 4.2 QS. One of the few things that totally refuse to work are the windscreen wipers. I've checked for blown fuses, no joy. There is no attempt at any movement of the wipers at all. I supect that it is the wiper stalk or a relay that is defective due to damp ingress from the flooded interior. Could anybody tell me where is the wiper relay located and which one is it? I would have thought that seized spindles or linkages would result in fuses blowing?

What I intend to do is connect a slave battery directly to the wiper motor. I've located the wiper motor and had it's loom plug apart, no sign of any corrosion present. Is there any particular wire that carries the +tive feed o the motor? I assume that the brown one is the earth, and therefore the -tive feed for the slave battery.

I look forward to hearing from the forums experts. Thanks for taking the time to read this.

Paul.

Dezzy · #2 29th December 2012, 03:14 PM

Not sure about your problem really, could be the stalk as you say.

The wiper relay is in the passenger footwell behind the sodden MDF board, as you look at the board it's on the bottom row and second from the right (trans tunnel) side.

green A8 · #3 29th December 2012, 08:43 PM

Thank You for that info Dezzy

I've found the little sod (relay) it seems to be corrosion free and nice and dry.

I had a play with the non functioning wipers today using the slave battery and a couple of test leads, I'm pleased to confirm that the wiper motor and linkages are fine, the spindles are a bit on the tight side, so I'll whip the assembly off and give them a clean/grease up. Looking inside the car at the wiper stalk, it looks to me as if the wrong part has been fitted to the car, there is no intermittant delay switch fitted to the top of the wiper stalk. The car is a 1998 model year. From memory I thought only the very early 8's were without this delay switch?

Oh, well another part to add to the list

Paul.

Dezzy · #4 30th December 2012, 08:25 AM

I'm not sure when they started having the intermittent delay switch on the top of the stalk, i don't have it but i'm on a 96. It has been mentioned on here before and someone like IT would probably know.

I was thinking, the relay i mentioned is the wiper intermittent relay and like Graynada i changed mine out for a programmable VW relay out a golf to get over the non adjustable time, and i think it's better than the 4 or 5 settings on the stalk.

green A8 · #5 31st December 2012, 01:16 PM

Quote:

Originally Posted by Dezzy

I'm not sure when they started having the intermittent delay switch on the top of the stalk, i don't have it but i'm on a 96. It has been mentioned on here before and someone like IT would probably know.

I was thinking, the relay i mentioned is the wiper intermittent relay and like Graynada i changed mine out for a programmable VW relay out a golf to get over the non adjustable time, and i think it's better than the 4 or 5 settings on the stalk.

Thanks for that info Dezzy. It sounds about right for a '96 not to have the intermittent delay switch on the stalk (our other family A8 QS 4.2 hasn't got one) But, I'd have thought a '98 M~Y car would have the switch. I'm certain that my Jan '98 3.7 Q registered company car had this fitted. Having a look at the steering wheel plastic shrouds on my project car, it looks like someone has at sometime removed them (one screw missing) I wouldn't be surprised if the windscreen wiper switch has been replaced. The wiper stalk looks to be a slightly different colour to the other stalks too.

It's not the end of the world, in spite of what millions thought

I'd be interested to know if an upgrade can be done without adding too many new wires, I'm not a very good sparkey.

So how does the VW programmable relay work then Dezzy? Might be an option. Mind you, at the moment there is no sign of life from the stalk switch, so it looks like I'll be forced to replace it.

Dezzy · #6 3rd January 2013, 10:28 AM

Well A8Parts will help with a replacement stalk if you need one.

The programmable relay works by turning the int wipers on, let it wipe once and return the stalk to off, then it's on a timer so when you need to wipe again just turn them on and it remembers the time between wipes. From 1 to 22 seconds i think

green A8 · #7 3rd January 2013, 05:51 PM

Thanks for that info once again Dezzy,

It would seem to me that the relay would be of more use than the rotary switch, which always seems to select either too much windscreen wiper action or too little, but never quite just enough. Sorry to pester, but do you have the VW part number?

Paul

Dezzy · #8 3rd January 2013, 06:26 PM

Here you go Paul take a look at this thread.
http://forum.a8parts.co.uk/showthrea...ighlight=wiper

HPsauce · #9 3rd January 2013, 06:34 PM

Quote:

Originally Posted by green A8

always seems to select either too much windscreen wiper action or too little, but never quite just enough

I'm pretty sure the timing set by the switch also varies with road speed too, though personally I'd rather control it that way than the variable relay process.
However, to get to the point I want to make, I'd be making sure it worked "as advertised" before going down that route. Though if you do have to replace the relay anyway that's probably easier and cheaper than the stalk......

green A8 · #10 3rd January 2013, 06:48 PM

Cheers for that Dezzy. I'll get one off fleabay and enjoy the mod

Looks like I still need to buy a new stalk but this sites sponsers can help out there

I'll be putting together a list of 'parts required' over the neax couple of days.

Once again Dezzy Thank You for your help

Paul