Bad Earth Causing Problems - Help

[northcave]

I bought a 92 300SL. The stereo didn't work properly but i tested it on my other car and it was fine. This led me to test the electrical feeds to the stereo and i found that the earth was bad. Not off but just not very strong.

I am worried that this may be causing other intermitent problems such as the roof / soft top not retracting and window wipers slightly unpredicatble.

Does any one know what other parts of the car would rely on this earth and whether there is an easy way to fix it? Wiring diagrams would be good.

Any suggestions would be great.

Thanks in advance

Tim

 

[television]

There are seperate earths all over the place, the radio should be earthed when its in the dash. too late tonight,you should take the problem a couple at a time

 

[Hibbo]

Try reseating and cleaning the pins on all the relays, quite a few things are switched via the earth return (although not the stereo )

 

[northcave]

...

Is there a general place where alot of earths are made or are they all over?

I mean if i get under the car would i be able to see if any have got corroded?

Tim

 

[eric242340]

Is there a general place where alot of earths are made or are they all over?

I mean if i get under the car would i be able to see if any have got corroded?

Tim

They are all over the car and looking underneath the car will not help you. This is not necessarily a faulty ground. As Malcolm said take it stage by stage. Report each problem as is and then people can help you. Im sure there are more problems but its very rearely a ground.

 

[northcave]

Stereo

Ok so taking the earth to the stereo. I have been told the same earth is used by the main Instuments and should check there first.

Does anyone know any easy way to get behind there. Will the main speedo/instruments panel pop out fom the back?

Thanks

Tim

 

[television]

If you want to take the cluster out you can do so by pushing from the rear. there is one large multi earthing bolt on the bulkhead behind the radio. the radio normally earths through the mountings.

I do not think that you will find any earthing points on the cluster. SLs have the long extension cables from the rear, that could be damaged.

Is it the radio or tape that does not sound OK

 

[northcave]

..

I tested the earth and it give a week signal on a half lit bulb... It tested the earth straight from the chassis and it was fine. The stereo worked fine with the ne earth. I've had a reasonable amount of experience fiting stereos bu thats not my concern really. It is whether the earth is shared by anything else and therefore could be acounting for the lights flashing on my cluster occaisionally.

But if you say the earth on the SL for the cluster isn't the same then it kinda of ansers my question.

Tim

 

[television]

I tested the earth and it give a week signal on a half lit bulb... It tested the earth straight from the chassis and it was fine. The stereo worked fine with the ne earth. I've had a reasonable amount of experience fiting stereos bu thats not my concern really. It is whether the earth is shared by anything else and therefore could be acounting for the lights flashing on my cluster occaisionally.

But if you say the earth on the SL for the cluster isn't the same then it kinda of ansers my question.

Tim

Tim , why not run a cable from the chassis of the radio to any bolt on the car substructure, its probably only earthing at the moment, via the aerial lead

 

[northcave]

..

oh yeah deffo. My last concern is the stereo though. I can make an earth for that and will do tonight. I just thought i might have found the proplem on my cluster also which would be something.

Cheers

Tim

 

[television]

oh yeah deffo. My last concern is the stereo though. I can make an earth for that and will do tonight. I just thought i might have found the proplem on my cluster also which would be something.

Cheers

Tim

This may solve it,you never know on these things, report back if there is any change in the instrument cluster

 

[northcave]

...

I got the cluster out ok and added an earth for the Stereo. Stereo working fine now but i filed down the existing earths to make a better connection. However they looked pretty good to be honest, as you'd expect from a mercedes.

I'll report back if i get the flashing lights again. They only happen every so often so it might be a week or two.

Thanks

Tim