'97 Disco 1 electrical problem

Could it be a bad earth somewhere?

Davy M

I think (hope) it might be a loose earth, but where is the most likely place?

Everything that has failed seems to be associated with the "multi function unit" in the electrical diagrams and the Haynes book seems to say this is in the driver's footwell. It does seem to need earths in the diagram.

Presumably this isn't in the fuse area, but is it inside the side bit where the door is hinged? I haven't had any time today, but did have a quick look and couldn't see anywhere else that a cover might come off.

In message , "Davy Murray @Blueyonder" writes

I think (hope) it might be a loose earth, but where is the most likely place?

Everything that has failed seems to be associated with the "multi function unit" in the electrical diagrams and the Haynes book seems to say this is in the driver's footwell. It does seem to need earths in the diagram.

Presumably this isn't in the fuse area, but is it inside the side bit where the door is hinged? I haven't had any time today, but did have a quick look and couldn't see anywhere else that a cover might come off.

Get your battery checked out, it may be going duff but not showing elsewhere yet!

In message , Bob Hobden writes

I'm no further ahead and think I'll have to save up to employ a professional. I've spent a couple of hours this morning with meter in hand in sub zero temperatures and am still waiting for the pain in my hands to subside.

I think the battery is OK. It starts the car, measures 'good' on my Wickes battery tester and charger and I've applied the Frankenstein tester (two handles to hold the metal rods that have a metal strip and meter between them) which read well into the green and smoked nicely.

I've found what may be the "multi function unit" in the electrics above the passenger footwell. What I haven't found are most of the 18 or so earth connections shown in Haynes.

There is another thing I just noticed not working, so the list is now

Interior lights Intermittent wipers (but normal wipers OK) Wipe part of wash/wipe Rear wash Rear wipe Heated rear window

Time to sit in the warm and trace out those circuits on the diagram(s), see if you can find anything common in the supply or earth side but I some how don't think you will. Don't forget to check supply/earth for any relays used.

It might be a combination of faults, all the rear stuff not working 'cause the door is no longer earthed or has to high a resistance in that connection.

I'm trying to extract the entire section from the RAVE manual for you but haven't yet cracked how to do so. In the meantime:

"The multi?function unit (MFU) is mounted on the rear of the passenger compartment fusebox and has an input to operation of the following:

• Heated rear screen

• Heated front screen

• Courtesy lights

• Side and headlights

• Rear fog guard lamps

• Headlamp power wash

• Front wipers

• Rear wash/wipe"

So your suspicions of where to look seem correct. Despite the location statement above, I've also seen another location mentioned "behind RH side of fascia on fascia fuse box" so look on both sides! Whichever side it's on I'm pretty certain that it's mounted on the back of the fuse box.

There's a test procedure for the MFU itself:

"Diagnostic Procedure

1. 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.
2. Press and hold the heated rear screen switch and switch on the ignition.
3. Release the heated rear screen switch within 2 seconds and the MFU will beep to indicate that it?s in diagnostic mode 1.
4. 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 oper-ated.
5. Pressing the heated rear screen again will cause the MFU to enter diagnostic mode 2.
6. The MFU will provide outputs to the following in order given below:

• Heated rear screen

relay energised for 2 seconds

• Heated front screen

energised for 2 seconds

• Courtesy lights

energised for 2 seconds

• Dim dip relay energised for 2 seconds

• Rear fog guard lamp energised for 2 seconds

• Headlamp power wash

energised for half a second

• Front wiper energised for half a second

• Rear wipe/wash energised for half a second

1. The MFU will then exit the diagnostic mode."

The earth connection for the MFU appears to be behind the RH footwell (side) trim panel above the front wiper relay.

I'll e-mail you some pictures - assuming that the published address works.

Dougal,

Many thanks. The pdf's to my email worked fine. I've printed them out and tomorrow I'll poke around again to see what happens.

I just wish it wasn't so cold.

I'll report back if/when it works.

Thanks again.

In message , Bill writes

In the end I went to a locally recommended auto electrician who delved in and reported back to confirm my suspicion that it was the MFU.

Unfortunately mine is the AMR 5360 and not the earlier 1280 version that lives on ebay. Googling reveals that this is a common fault and that they are difficult to find except by placing an order at full price with a dealer.

I will try more breakers just in case there is one out there - I'd like to have a spare before trying to go in with a soldering iron. Has anyone fixed one of these?

At the prices I've seen for new ones I'd be tempted to go in anyway - you've lost most of the functionality already. I'd be looking for LandRover's too frequent dry joints which are usually easily spotted.