The Electrical gremlin thread.......

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The Electrical gremlin thread.......

Apr 30, 2006
East Yorkshire
So you have had one or combination below:

  • Imobiliser light staying on
  • Random power steering issues
  • Battery charging issues
  • Lights looking dimmer than normal
  • Airbag light coming on
  • Car been weak starting dispite battery been healthy
  • Random temperature gauge readings

These all can be a symptom of a bad earth/s in the engine bay.. So before you go shelling out your hard earned cash take 10 mins to try the following.......

Firstly ensure the battery terminals are all nice and clean and tight...

If you find something like this

its time to get cleaning.......

(Safety glasses and rubber gloves are a good idea when working on the battery)

First swill with a strong bicarbonate of soda solution in HOT water... and rinse well

next undo the clamps (negative first)

and clean the terminals and clamps with emery paper or a proper terminal cleaning tool

and put back together..... (negative LAST)

grease the terminals with either Vaseline or a dedicated terminal grease..

More info in removing the clamps here:

(if the electrical system has been so neglected that the above has happened you might as well continue to do the rest below whilst your at it)

Next follow the negative lead from the battery

it goes from here


down to the left chassis leg where its bolted on.....



Take it off clean the stud nut and crimp with either emery paper or scotchbrite and reassemble.... And smother with grease....

then follow it further......

to the top of the gear box..


Now some member (i cant remember who came up with a cracking tip to use a cut down cheap 13mm spanner to save messing about with the clutch slave and the possibility of needing to bleed it after)

anyhows this is the nut you want to get at and again clean all the parts...


and yet again grease it to keep the damp off it.....

and the other common issue is this little begger:


Which is hiding under the air box

which is removed thus:

on top of the rocker cover (1.2 and 1.4 8v) again clean the parts (only use high melting point grease here due to the heat of the engine)

Now if you have done these steps and your still having issues.......

One more check..........

take a pair of jump leads......

Connect one lead to the NEGATIVE battery terminal (NEVER THE POSITIVE FOR THIS CHECK)

connect one end to here on the negative battery

battery - terminal.JPG

the other to here (green to green)

engine mount.JPG

This bypasses the earth strap to the engine

and the other to here (purple to purple) is bypasses the section between the engine and the chassis ((this needs to be done as the mount is isolated on a rubber mounting))

Doing this you can remove one clamp and check by process of elimination which part of the earth strap is having issues

chassis mount.JPG

Its not overly rare for the earth cable to break down internally due to water ingress and vibration and fail

Car won't turn off.... battery runs flat random things power up

Check the engine bay fuse box

Remove the lid is it dry inside?

If not dry it out often people fail to fit the lid correctly and subsequently lets water in causing all sorts of strange electrical issues

Even if it looks dry. Remove it off its rubber mountings remove the multi plugs and stick it on a radiator use a hair drier to dry the plugs..
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Andy, an excellent guide. I was able to locate and clean all the earthing points shown. In the way of thanks I've taken photographs of other earthing points that I located on my journey.

Note that my vehicle is RHD so those with LHD vehicles should translate the following accordingly.

Firstly there is an additional earthing point at the back of the engine which is only visible from underneath the car. It's located above the oil sump, beside the alternator:

Rear of Engine earth above Oil Sump.jpg

Moving inside the car there is a dashboard earthing point located on the lower passenger-side A-pillar, below the BCM:

Passenger side lower A-pillar.jpg

An additional dashboard earth can be located on the right-hand side of the centre console (on RHD cars this is next to the pedals):

Driver side Dashboard earth.jpg

Underneath the centre console itself is an airbag system earth (be careful not to disturb the airbag sensor):

ABS sensor earth underneath centre console.jpg

Finally, an earthing point that many will be familiar with can be located in the boot underneath the left-hand side trim:

Boot Passenger side.jpg

Obviously the earthing points in the engine bay are more susceptible to the elements so are more likely to require maintenance, however these may prove useful to some folk trying to cure electrical gremlins.

It's worth noting that some earthing points will vary according to model and specification. For more details, reference eLearn here:
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Having compared my photograph of the Airbag earth (under the gearbox centre console) to the Haynes manual, I realised that I have 1 earth connected whilst the Haynes photograph shows 2:

C050 - Airbag earth underneath centre console.jpg

eLearn cites 2 wires connected to this earthing point; C050A and C050B, corresponding to Airbag System Earth Dashboard and Rear respectively:

Does this mean that I'm missing an earth lead? Is the airbag configuration model dependent?
Andy, in your OP you stated:

"Its not overly rare for the earth cable to break down internally due to water ingress and vibration and fail".

How does one test cables that appear ok on the outside for internal wear?

If any earth cable in the engine bay were internally broken would it be reasonable to expect a myriad of electrical gremlins?