Earth behind dash on 92 200Tdi

[JonM]

I am trying to work out why I lost electrical power last week [all dash dead, and of course no fuel to engine] and it subsequently cured itself.

I am looking at voltage drops. Battery negative terminal to chassis is nothing, so no problem with chassis earth strap.

Voltage at the battery condition indicator is 0.6 lower than across battery [engine running, alternator output 14V],

further 0.6 drop when heater fan is put on high.

So I am looking for the point where the earth wires behind the dash are connected to the chassis, and the point where the heater earth is located.

Thanks.

[errol209]

I am trying to work out why I lost electrical power last week [all dash dead, and of course no fuel to engine] and it subsequently cured itself.

I am looking at voltage drops. Battery negative terminal to chassis is nothing, so no problem with chassis earth strap.

Voltage at the battery condition indicator is 0.6 lower than across battery [engine running, alternator output 14V],

further 0.6 drop when heater fan is put on high.

So I am looking for the point where the earth wires behind the dash are connected to the chassis, and the point where the heater earth is located.

Thanks.

IIRC everything in around the dash is grounded on the bulkhead, and no seperate earth strap is provided betwixt bulkhead and chassis. The battery negative should go to the gearbox or starter motor, and the starter motor and engine should also be strapped to the chassis (one each). This would fit with your symptoms, i.e. there is a volt drop between bulkhead and chassis.

[JonM]

Thanks. Can you tell me exactly where on the bulkhead the earthing is or should be? I can't see anything for the jungle of wires.

[gilloverland]

I had a similar problem about a year ago, it wasnt an earth, it was the brown (live) wire on the ignition switch that was loose - hope this helps...

[western]

Thanks. Can you tell me exactly where on the bulkhead the earthing is or should be? I can't see anything for the jungle of wires.

to vehicles right of fuel filter [see the screw inside yellow ring on attached photo]

[JonM]

Thanks Western! Is that also the heater earth?

[western]

I believe so, there are numerous black earth wires on that screw, from various places.

[DaveSIIA]

Voltage at the battery condition indicator is 0.6 lower than across battery [engine running, alternator output 14V],

further 0.6 drop when heater fan is put on high.

Measure the voltage from each terminal of the battery condition monitor to a good earth (battery -ve terminal). If there is anything between the negative terminal and earth then you have a grounding problem. However, if the good earth to positive of the battery monitor is less than the battery voltage you have poor contacts in the supply side (master fuse box, ignition switch, etc).

Test is best done with as much electrical load as possible switched on. Measure alternator, battery and auxillary circuits under the same load conditions.

HTH

[Ex Member]

Thanks Western! Is that also the heater earth?

The heaters earth through the speed switches. Power is supplied directly to the heater. It is a strange backwards arrangement....

[Staffo86]

Hi after reading this I have similar problem, but mine is when engine is running when lights are off the dash lights are on on when I put my lights on the dash lights go off but only my little side lights come on but when I move the heater switch down a touch everything comes on and the heater doesnt work what so ever any ideas cheers jay defender 200tdi