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DiscoDean

New Member

• Feb 12, 2007

• #1

Hi All,

This is my first post to the forum since getting our Disco last December, She's an L reg 200tdi S. However just recently she has developed an unusual electrical fault.

When the headlights are on and using the screen wash it is causing the radio to cut out momentary and there is a clicking from the inbuilt subwoofer unit in the rear door. This noise also occurs when the brake pedel is pressed and also when the Disco is put into reverse gear. I have also noticed that when the screen wash button is pressed there is an intermitant click noise from under the glove compartment, very much like a relay switching.

Could this be the problem, a faulty relay? When the brake pedel is pressed there is also a slight dimming of the dash lights and interior light.

I hope someone will be able to help me put this right.

Deano

 

clutchdust

Well-Known Member

• Feb 12, 2007

• #2

start with the simple stuff first, check the battery condition and alternator charge rate, sounds to me like low voltage especially when you say that the dash lights dim when the brake is pressed, do the headlights dim aswell?
What about operating the washers with the headlights off? does this have an effect on the radio?

If the battery and alternator are ok then it could be an earth fault (corroded or loose connection)

 

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DiscoDean

New Member

• Feb 12, 2007

• #3

Hi Clutchdust, thanks for the reply.

I do think that it could do with a new battery, it turns over quite slow from cold.

clutchdust said:

What about operating the washers with the headlights off? does this have an effect on the radio?

Click to expand...

Yes, the radio does not cut out when the headlights are off. Very puzzling

My local motor spares does a free battery and alternator test, I will get that done this weekend.
If its a bad earth, how can I cure that?

 

clutchdust

Well-Known Member

• Feb 12, 2007

• #4

DiscoDean said:

Yes, the radio does not cut out when the headlights are off. Very puzzling

My local motor spares does a free battery and alternator test, I will get that done this weekend.
If its a bad earth, how can I cure that?

Click to expand...

Try it with the heated rear window turned on, then operate the washers, if this causes the radio to play up then i'd say definately low voltage.

Bad earth can be a tricky one, get a wiring diagram and look at the earth points for the systems that are playing up, are they connected to the same ground point? if so then that will cause you the problem if its corroded or loose.

Get the battery and charge rate checked first before you delve in too deep.

Other easy checks you could do are to make sure the battery terminals are clean and tight and the engine earth strap is clean and tight, engine earth will cause charging problems and slow cranking if its not a good connection, loose/corroded battery terminals will cause the same.

 

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DiscoDean

New Member

• Feb 12, 2007

• #5

I've just gone outside and tried the washers with the heated rear screen on and the radio says on, the clicking noises and the radio cutting out only happens when the headlights are on, it doesn't happen if only the side lights are on.

 

clutchdust

Well-Known Member

• Feb 12, 2007

• #6

You're going to have to diagnose this carefully and systematically, It is a strange fault you have there but if you think about it, it's probably something really simple. A 200tdi isn't a complicated vehicle with regard to electrical systems so bad earth, battery or alternator does seem a likely cause. I don't have a wiring diagram for a 200 but I'm thinking that maybe the washer pump and headlamps share the same earth point and the currant draw due to a bad connection could interfere with the radio.

 

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DiscoDean

New Member

• Feb 12, 2007

• #7

Thank you for the advice, I shall investigate more at the weekend and also get the battery and alternator checked.
I'll keep you posted.

 

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DiscoDean

New Member

• Feb 18, 2007

• #8

I've had a new battery fitted which has improved the cold starting and the alternator is also working fine. The fault with the radio cutting out is still there, I just cannot seem to find what the problem is, i've checked the earth points (the ones I can see) but this hasn't made any difference.

To recap, the radio cuts out when the screen washers pushed only when the head lights are on. There is also an electrical click from the subwoofer when the brake pedel is pressed, again only when the head lights are on, this also sometimes happens when the heated rear screen is running.

I'm compleatly baffled