Iffy electrics!

Toad · Nov 22, 2013

Hi

I am having a bit of a do with my electrics at the mo. I have a Discovery 1 300Tdi ES Auto and periodically my courtesy lights, rear wiper, front intermittent wipers, heated windows, front and back, and front and back wash wipe stop working. I haven't been able to tell which of these things if any are causing the problem, but it's a real pain when it happens. I have checked the entire fuse box and all the fuses are okay, but I wouldn't have thought all the above would run off one fuse anyway.

Could it maybe be an earth problem, and are there multiple earth points on theses motors, and if so can anyone tell me where they are? I like to try and sort things out myself really before I resign myself to having to call in someone else! Any ideas would be really appreciated.

discool · Nov 22, 2013

All those items/functions plus the rear fog lamps go through on unit, that is the Multi Function Unit that's plugged into the rear of the fuse box, the electrical connections may be loose or the unit it's self maybe faulty.
Earth points are behind both footwell kick panels.

discool · Nov 22, 2013

Just do a MFU function test.

Close all doors and the tailgate. NOTE: If the oil pressure switch goes open circuit (engine is started) during the following procedure, the MFU will exit the diagnostic mode immediately.
Press and hold the heated rear screen switch and switch on the ignition.
Release the heated rear screen switch within 2 seconds and the MFU will beep to indicate that it's in diagnostic mode 1.
Press the heated rear screen switch; the MFU will beep twice. In turn, operate each of the following switches, heated front screen, rear fog guard lamps, side lights, headlights, front wiper, and rear wiper. The MFU will beep twice each time a switch is operated.
Pressing the heated rear screen again will cause the MFU to enter diagnostic mode 2.
The MFU will provide outputs to the following in order given below:
Heated rear screen relay energized for 2 seconds
Heated front screen energized for 2 seconds
Courtesy lights energized for 2 seconds
Dim dip relay energized for 2 seconds
Rear fog guard lamp energized for 2 seconds
Headlamp power wash energized for half a second
Front wiper energized for half a second
Rear wipe/wash energized for half a second
The MFU will then exit the diagnostic mode

Toad · Nov 22, 2013

discool said:
Just do a MFU function test.

Close all doors and the tailgate. NOTE: If the oil pressure switch goes open circuit (engine is started) during the following procedure, the MFU will exit the diagnostic mode immediately.
Press and hold the heated rear screen switch and switch on the ignition.
Release the heated rear screen switch within 2 seconds and the MFU will beep to indicate that it's in diagnostic mode 1.
Press the heated rear screen switch; the MFU will beep twice. In turn, operate each of the following switches, heated front screen, rear fog guard lamps, side lights, headlights, front wiper, and rear wiper. The MFU will beep twice each time a switch is operated.
Pressing the heated rear screen again will cause the MFU to enter diagnostic mode 2.
The MFU will provide outputs to the following in order given below:
Heated rear screen relay energized for 2 seconds
Heated front screen energized for 2 seconds
Courtesy lights energized for 2 seconds
Dim dip relay energized for 2 seconds
Rear fog guard lamp energized for 2 seconds
Headlamp power wash energized for half a second
Front wiper energized for half a second
Rear wipe/wash energized for half a second
The MFU will then exit the diagnostic mode

discool said:
All those items/functions plus the rear fog lamps go through on unit, that is the Multi Function Unit that's plugged into the rear of the fuse box, the electrical connections may be loose or the unit it's self maybe faulty.
Earth points are behind both footwell kick panels.

Those are two great replies, thanks very much. I am due at work shortly so won't get a chance to do anything until the weekend. Can you just tell me that when doing the MFU function test, will it be obvious if it finds a fault. In other words what should I be looking for once its completed the test? Or is the test an attempt at putting right whatever may be wrong? When you say if the oil pressure switch goes open circuit, do you mean I only need to turn the ignition on one notch on to auxiliary, or do you mean turn completely so the oil lights on, but just don't start it?

Thanks again Discool.

discool · Nov 22, 2013

It just a pure function test of the circuits the MFU looks after, if you don't see a light or hear the relay etc etc then that circuit has a problem, somewhere.

It's just what is states,
"If the oil pressure switch goes open circuit (engine is started) during the following procedure, the MFU will exit the diagnostic mode immediately".
So don't start your engine.

KeepDigging · Nov 22, 2013

An absolute mine of information!

Thanks.

Iffy electrics!

Toad

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discool

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discool

Well-Known Member

Toad

Active Member

discool

Well-Known Member

KeepDigging

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