TD5 2001 Electrical problems

[frenchdisco5driver]

Hello,

Since a couple of years (yes), we have serious technical problems with our Disco II TD5.

When it's hot or after two hours on the motorway, the following things fall down:

Central locking, rear windows, rear wiper, intermittent front wipers, direction indicators, hazard warning indicators.

We also had the same problems when it was very cold (this winter).

After a few hours, everything comes back to normal.

It's a bit embarassing so if you could help me, I would very much appreciate.

Apart from that, we are very satisfied by our Disco.

I apologize for my english, which is for sure not "ideal".

Thanks very much in advance

All the best from France

Gerard

[BogMonster]

The things you are having problems with are all controlled by the body control unit and something called the IDM which is basically a lot of relays which live inside the back of the main fuse box.

It's usually caused by water ingress from a leaky windscreen, but I guess maybe it could be a temperature related problem with the same electronics. I think that's where your problem will be anyway, though exactly why it's happening, I'm less sure about.

[HarrysLandy]

It is almost definite that your problem lies with the BCU. There are numerous reasons as to why it is malfunctioning including water and temperature damage, or a combination of the two.

I'm not too sure about this, but I've read that welding can affect the ECUs on the Discovery.

The Discovery has lots of electronics, especially the Td5 so one simple thing could cause a whole system to shut down, therefore it isn't necessarily the BCU that has broken, it could be something that the BCU relies on to work.

Sorry I couldn't be more helpful, but this is just what I know from experience.

[frenchdisco5driver]

Hello

Thank you HarrysLandy and BogMonster four your contribution.

I had effectively heard about IDM and BCU, and possible problems in communication between both.

I have been told also about a relay becoming hot so it couldn't work properly.

The thing is now to determine which relay.

Do you think that using tools such Nanocom we could go any further?

Thanks again

Cheers

[BogMonster]

I doubt it - most of these sorts of problems cannot be diagnosed with the computer because the modern ECUs are very good at diagnosing problems in other circuits they talk to, but very bad at diagnosing problems with themselves. A bit like human beings

Your best bet is to get a wiring diagram and work through each affected circuit trying to draw a link between which circuits have a common component. Sometimes (if it is water ingress) if you pull the fusebox out and take it apart the cause is very obvious - the circuit board will be very green and corroded - and the fault is obvious and needs a replacement unit. I would do that first, it isn't too difficult, a couple of hours would be enough to do it.