Rear wiper motor shorting

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30th September 2011, 07:37 AM
Aquarian51

Rear wiper motor shorting

I noticed the other day that when I use the rear door wiper my voltmeter does a big dip down below 8 volts each time the wiper does a sweep across the glass. I've had a quick look and can't see any obvious sparks or wearing of insulation of the wires. It hasn't blown a fuse - as yet. Any ideas: is it a common fault, things to look at or check? Advice gratefully received. Thanks
30th September 2011, 07:55 AM
Bigrig

Hey mate - the wiper motors have a tendency to die and are fairly cheap and easy to replace - I'd suggest checking the wiring from the motors first, but if no obvious signs or issues, then possibly replace them (may as well do both for the cost and effort whilst doing it).
30th September 2011, 08:15 AM
patch697

Quote:

Originally Posted by Bigrig

Hey mate - the wiper motors have a tendency to die and are fairly cheap and easy to replace - I'd suggest checking the wiring from the motors first, but if no obvious signs or issues, then possibly replace them (may as well do both for the cost and effort whilst doing it).

You talking Wiper motors or washer motors here Bigus?
30th September 2011, 08:21 AM
patch697

Quote:

Originally Posted by Aquarian51

I noticed the other day that when I use the rear door wiper my voltmeter does a big dip down below 8 volts each time the wiper does a sweep across the glass. I've had a quick look and can't see any obvious sparks or wearing of insulation of the wires. It hasn't blown a fuse - as yet. Any ideas: is it a common fault, things to look at or check? Advice gratefully received. Thanks

I had a similar issue & found that dust had got into every part of the wiper assembly & after a removal rigorous cleaning & a good spay with dir lube it was all good again.

Its not a fun job but all it cost me was time & the end result was worth the trouble.
30th September 2011, 09:26 AM
Ben-e-boy

Hi

I had a similar problem at work a couple of days ago where a plug for a hydraulic valve had a nic on the cable inside the plug and it was dragging the voltage from 240 when disconnected to 27 connected without blowing fuses or breakers what I refer to as a "long short"

What I would do first is disconnect the motor from the circuit the turn the wipers on. If the voltage still drops you have a cable fault if it dosnt you have a motor fault
If you have a cable fault thoroughly inspecting the cables. If its a motor fault I would do as patch said by cleaning but use "CONTACT CLEANER" its readily available. Its a solvent designed for use on electrical and electronic equipment failing that get a new one

Hope this helps
Cheers
Benny
30th September 2011, 09:58 AM
patch697

Quote:

Originally Posted by Ben-e-boy

Hi

I had a similar problem at work a couple of days ago where a plug for a hydraulic valve had a nic on the cable inside the plug and it was dragging the voltage from 240 when disconnected to 27 connected without blowing fuses or breakers what I refer to as a "long short"

What I would do first is disconnect the motor from the circuit the turn the wipers on. If the voltage still drops you have a cable fault if it dosnt you have a motor fault
If you have a cable fault thoroughly inspecting the cables. If its a motor fault I would do as patch said by cleaning but use "CONTACT CLEANER" its readily available. Its a solvent designed for use on electrical and electronic equipment failing that get a new one

Hope this helps
Cheers
Benny

I should have been a little more descriptive & said I sprayed the moving parts with dry lube & not the internals of the motor itself.

Cheers Benny & top tips to mate.
30th September 2011, 10:23 AM
Aquarian51

Thanks Benny. I'll try that to establish what is at fault. Will post the result so it may help others in the future.
cheers
Len
30th September 2011, 10:32 AM
patch697

Quote:

Originally Posted by Aquarian51

Thanks Benny. I'll try that to establish what is at fault. Will post the result so it may help others in the future.
cheers
Len

Good onya Len & best of luck mate.

If you get stuck just jump on & someone with be sure to help out.
30th September 2011, 01:49 PM
Yendor

Does the voltmeter also drop when you use other electrical items such as indicators or when headlights are turned on?

If so I would check the main earth that runs from the negative side of the battery to the body, is it clean and tight?, also I would check the main earth for the dash, from memory it connects in the panel around the inside fusebox.

Does the rear wiper move slowly or is jerky in it's movement? I would try lubing up the wiper mechanism as per Paul post.
30th September 2011, 02:17 PM
Ben-e-boy

Quote:

Originally Posted by Yendor

Does the voltmeter also drop when you use other electrical items such as indicators or when headlights are turned on?

If so I would check the main earth that runs from the negative side of the battery to the body, is it clean and tight?, also I would check the main earth for the dash, from memory it connects in the panel around the inside fusebox.

Does the rear wiper move slowly or is jerky in it's movement? I would try lubing up the wiper mechanism as per Paul post.

If the main earth has a high resistance joint you will have more issues than just the wipers
23rd October 2011, 05:46 PM
Aquarian51

Sorry it's taken me so long to get back to this thread.

The problem was that the voltmeter picked up it's supply from the rear wiper motor switch on the dashboard. One of the sparkies at work had meggad 'a wire that was live with ignition' for me to supply the voltmeter with - rather than run it from the battery and it being live continuously.

Is there a better source for the supply to the voltmeter? Please advise. Thanks
23rd October 2011, 06:21 PM
Yendor

Quote:

Originally Posted by Aquarian51

Sorry it's taken me so long to get back to this thread.

The problem was that the voltmeter picked up it's supply from the rear wiper motor switch on the dashboard. One of the sparkies at work had meggad 'a wire that was live with ignition' for me to supply the voltmeter with - rather than run it from the battery and it being live continuously.

Is there a better source for the supply to the voltmeter? Please advise. Thanks

This is not genuine, someone must of rewired it this way. They normally run off different fuses.

The voltmeter (like any gauge) is just a guide, so any ignition feed will do.

Doing this I don't think you are fixing the problem, just covering up the symptom.

I still think you have a voltage drop issue.

Did you check the earths?
26th October 2011, 05:21 PM
Aquarian51

Quote:

Originally Posted by Yendor

Does the voltmeter also drop when you use other electrical items such as indicators or when headlights are turned on?

If so I would check the main earth that runs from the negative side of the battery to the body, is it clean and tight?, also I would check the main earth for the dash, from memory it connects in the panel around the inside fusebox.

Does the rear wiper move slowly or is jerky in it's movement? I would try lubing up the wiper mechanism as per Paul post.

The voltmeter only dropped below 8 volts (the minimum reading) when the rear wiper actually wiped, so it was an intermittent drop of voltage. The wiper just did a steady slow wipe of the window. It dipped of course when the glow plug was engaged, but when the engine started the volts were pretty consistent around the 13-14 volt mark.

I did what Ben-e-boy suggested and disconnected the motor and the voltage drop still occurred, which indicated that it was a wiring issue - not a motor problem. That's when I decided to follow the wiring from switch to wiper and realised the voltmeter was using it as its power source.

I checked the earth connection from the battery and dashboard, and lubed the wiper motor.

I've disconnected the voltmeter from the wiper wire, so it is not connected to anything at the moment, while waiting for advice of maybe a better 'ignition source' to connect to.