electrical mystery

[Lou013]

Hello chaps and best wishes to all of you,

I was trying to work out why my fuel gauge was working only when the car was wet and I found this :

http://imgur.com/AsFCE7D

http://imgur.com/c6aUktz

it is hidden below the brake fluid pot on the driver side. When shaking it some odd white powder is coming off..

Does someone know what it is and what is its purpose ? I can't find it on the electrical schemas...

Thanks

[zombeh]

They're the dimmer resistors for the dash illumination. The power for the lights in the instruments goes through neither, one or both depending on the position of the dimness switch.

[Lou013]

thanks

I think mine are damaged because my fuel gauge was working only when wet...

[Oldred_V8S]

They are, as stated above, the resistors for the dash lights. You can bypass them to increase the dash lighting from very dim to just dim.

I would suggest you get a multi-meter onto the fuel gauge sender and associated wiring to track the fault down.

Edit to add

Test the wiring under load by putting the meter leads into the back of the plugs, or back-probing (stop sniggering Glen) don't just unplug the leads and put the meter probes into the plugs.

The sender unit is just a simple rheostat and would be simple to test on the ohm setting, but must be disconnected for this test.

Edited by Oldred_V8S on Monday 4th January 12:32

[Lou013]

the sender is fine, i've tested the ohm when I've replaced it.

Since I have shaken the dimmable resistor the fuel gauge is now working.

Other thing the clock on the dash is not working, there is no power on the wire coming on it, this wire has the same colour as the one plugged onto the dimmable resistor...

[phillpot]

zombeh said:

The power for the lights in the instruments goes through neither, one or both depending on the position of the dimness switch.

Not wishing to be pinickety but they look like they are wired in series (as mine were) to give OFF - DIM - ON (12volts), not enough positions on the switch for two levels of dimness




Should have nothing to do with fuel gauge issues. Maybe a bad earth at the fuel tank made better when wet?

[Blue 30]

Working when wet ?
That sounds like the water is creating an electrical connection !
And the most obvious is a bad earth on the fuel tank.
You could simply first try a long jump lead from the battery -Ve (neg/earth) pole, to the metal case of the tank.
Then turn the Ign 'on' & see if the gauge reads (assuming you do have some fuel in the tank).
If that works, you will just need to replace the original tank earth wire or bad connector(s).
If that test doesn't make the gauge work, then you're looking at a 'sender to gauge' wire problem, the gauge itself, or the power (+Ve & -Ve) to the gauge, as VDO gauges are usually 3-wire working (+/- & sender wires).

TB.

[zombeh]

phillpot said:

Not wishing to be pinickety but they look like they are wired in series (as mine were) to give OFF - DIM - ON (12volts), not enough positions on the switch for two levels of dimness

I guessed and didn't actually look too hard since "as bright as it goes" isn't really bright enough I've never turned mine down to see what the other choices were and it didn't occur to me that off might be an option.

[glenrobbo]

Oldred_V8S said:

Test the wiring under load by putting the meter leads into the back of the plugs, or back-probing (stop sniggering Glen)

Who? Me?

As if........




:snigger: