Weak Electrics

[northcave]

Please read all before replying:

When i got my 300sl the stereo didn't work so i tested it and the stereo unit was fine. However i then discovered that the earth to the stereo was weak. Not dead but just too weak to function the stereo properly.

Other issues:
All lights on main speedo console are very dim.
Engine revs drop when using electric windows or hood.
Occaisional warning light for rear lights although bulb is good.
Intermintent indicator / wipers

I know it was only the earth to the stereo but i wonder what other units share that same earth and if it might be cause a whole host of additional problems.

Has anyone got any suggestions?

 

[anyweb]

regarding this part > All lights on main speedo console are very dim.

have you tried adjusting the rheostat to increase brightness ?

on my c220 i have two knobs in the instrument panel, one for resetting the latest mileage, and the other for setting time, the first one can also be twisted left/right to decrease/increase brightness in your instrument panel

worth a mention i think

the rear bulbs may need the bulb holders cleaned properly as they can get covered with non conductive residue,

as regards the intermittent wipers/indicator, try checking for this post for the very same problem

cheers
anyweb

 

[northcave]

well bend me over and tickle my balls,,,, i feel bit silly now... yes twisting the nob worked on the console.

I suppose that solved makes the earth problem less of an likely...

Is there any way to find out though what other items in the car share the earth that goes to the stereo. i doubt it has one all of its own.

Thanks very much so far!!!!

 

[Legoman]

the rear lights on mine caused a similar problem i guess , the previous owner soldered some cable to the negative part of the circuit frame and connected the other end to the chassis to resolve this.

as for what shares the same earth , i guess the components will also share the same fuse as well.

 

[television]

Earths on cars are in the form of star fittings, that is many connections on one bolt. there are a few under the dash both sides, the battery earths should never be ignored

 

[mattkh]

i guess the components will also share the same fuse as well.

Not always the case.

 

[bigasotonuk]

Hi,
I would check as Malcolm says your Battery earth and see if the earth strap to the engine is clean and intact.

 

[wireman]

If the battery ground strap is dodgy the strater motor will be very lazy.

Check grounds by measuring the voltage drop across the connection whilst the load is switched on. Any significant voltage (say >0.25v) means that the ground connection is a bit iffy.
Crimp lugs can get nasty corrosion inside where the wire enters (you can not see this bit unless you cut the lug in half) and go high resistance, checking for volts drop is an easy check.

Rub off any of the zinc oxide that forms on the fixed contacts in the rear lamp clusters and check the riveted bars which form the internal interconnections are sound and clean at the junctions, they get tatty after a few years. If you clean the junctions up soft solder will help improve the rivet connections but it must be very clean and totaly grease free before you start any solder repairs, galvanised steel is classed as a difficult to solder material in my book.
A light coating of waxoil from an aerosol will preserve the integrity of these assemblies.

Make sure that the tail lamps are 10w and not 5w bulbs or the warning indicator goes in for erratic behaviour.

 

[bus no 808]

Whoohooo, Anyweb you are my hero. I now have dashlights. No more driving blind, ahem, as it were. See what speed I am doing. Whoohooo. Brilliant. I should twiddle a few more knobs and see what happens.

 

[Old Hat Shop]

Make sure that the tail lamps are 10w and not 5w bulbs or the warning indicator goes in for erratic behaviour.

This worked for me. bulbs are the same fitment and all worked, but the different rating, shows up as an error. Clever, these Mercs.