Disco blues

[Prajna]

Hi all, I have a very dear neighbour who has a 1992 Disco 1. My mate, Mike is working through the mechanical deficiencies but it falls to me to address the electrical quirks. The main impediment is that I am finding it next to impossible to track down a fuse/relay diagram or circuit diagram for the beast. Fuse layout diagrams are plentiful for the Disco 1 from '94 onwards but it seems nobody knows about 90 - 93 discos. In '94 they brought in ECUs etc, so everything related to electrical systems changed. This LR is left-hand drive too and the fuse box (under the steering column and the only fuse box I can find - no engine bay or under seat fuses) has three equal length columns of fuses with no relays, whereas the later models have a main fuse section and two smaller satellite sections and a few relays.

At the moment I'm trying to fix the electric windows, which have power at the fuses and at the switches in the centre console but 0v at the connector block just before the loom goes through to the door.

A circuit diagram would, I feel, be of some considerable assistance. Does anyone have any hints where I might obtain such a rare and exotic item?

TIA

 

[Bobupndown]

Make contact with early Discovery 1 'GWAC' enthusiasts. They will be able to help.

G-WAC notes – Project Jay Preservation Group

pjpg.co.uk

 

[AKN]

I have a couple of ‘93 Range Rovers, likely as not the circuit will be the same. If you are not in a rush then I can look up the ETM section on the windows but I won’t be near it for a couple of weeks. Try with the 95 model year circuits I don’t think they changed. There is a black module probably under the centre armrest/cubby box which controls the windows they have been known to fail. Do the rear windows work? They don’t go through that ecu.

 

[pedrobedro]

Try on land rover forums, someone might have a pdf version.

 

[Prajna]

I have a couple of ‘93 Range Rovers, likely as not the circuit will be the same. If you are not in a rush then I can look up the ETM section on the windows but I won’t be near it for a couple of weeks. Try with the 95 model year circuits I don’t think they changed. There is a black module probably under the centre armrest/cubby box which controls the windows they have been known to fail. Do the rear windows work? They don’t go through that ecu.

No ECU in the '92 Disco. I have power at the switches but don't know where the wires go between there and the doors. There are relays in the door posts/side of the footwells but I don't know if the windows are on a relay. I don't see slate/blue and slate/pink or slate/red and slate/black (window motor wire colours) at the relays.

 

[AKN]

It is not normal to put relay in window circuit other than the ecu for one touch down. Do any of the windows work? If one does try swapping the switches with a non working one.

This is the book you need:-
https://www.brooklandsbooks.co.uk/product/land-rover-discovery-1990-1994-workshop-manual/

At the 95 model year LR went to RAVE a digital document system which is why post 95 pdfs are easy to get anything before that was paper so had to be scanned.

 

[Trevorleach]

Fusible links built into drivers side loom on the inner wing, I kid you not.
Extra battery/chassis earths are an essential mod.

 

[Prajna]

It is not normal to put relay in window circuit other than the ecu for one touch down. Do any of the windows work? If one does try swapping the switches with a non working one.

This is the book you need:-
https://www.brooklandsbooks.co.uk/product/land-rover-discovery-1990-1994-workshop-manual/

At the 95 model year LR went to RAVE a digital document system which is why post 95 pdfs are easy to get anything before that was paper so had to be scanned.

Very helpful, thanks AKN. It's a 3 door and neither window works, so swapping switches won't help but I would'a done it if it was just one.

 

[Prajna]

Fusible links built into drivers side loom on the inner wing, I kid you not.
Extra battery/chassis earths are an essential mod.

Yeah, so I heard. Are the fusible links easy to recognise? I don't have the Disco here atm to investigate; jumped the windows closed via the connector in the door post/footwell and she's gone off with it until we have time to diagnose further.

 

[AKN]

Here is a picture with the fusible links in my RR LSE

 

[Prajna]

Here is a picture with the fusible links in my RR LSE

View attachment 359652

Thanks AKN. So fuseable links = fuses? And I'll have to shift that sleeve/covering to test them? If they've blown then what's involved in fixing them?

 

[AKN]

jumped the windows closed via the connector in the door post/footwell

Do I understand this to mean you can make the windows move under power? Has the car been laid up for some time? My LSE was very reliable as an everyday use car but now it gets little use things like switches are giving trouble due to oxidation. So it could be worth trying some proper contact cleaner into the switch or get a replacement.

Thanks AKN. So fuseable links = fuses? And I'll have to shift that sleeve/covering to test them? If they've blown then what's involved in fixing them?

You said earlier that there was power at the fuse box and switches so the fusible links are fine. They are basically under rated wire which will burn out in the event of a wiring fault between the battery and the fuse box. If one does fail many things electrical will not be working.

 

[OJCar]

I have a 1990 and a 1992 Discovery and use the Haynes manual (3016) and the Factory workshop manual

https://www.ebay.co.uk/itm/234659414670?hash=item36a2ca828e:g:E5sAAOSwXhth4ugl

Land Rover Discovery 1990-1994 Factory Workshop Repair Manual SJR900 Uk Freepost | eBay

Land Rover Discovery 1990-1994 Factory Workshop Repair Manual SJR900 Uk Freepost.

www.ebay.co.uk

Both have wiring diagrams.

Which engine is in your friends Discovery?

 

[Trevorleach]

Yeah, so I heard. Are the fusible links easy to recognise? I don't have the Disco here atm to investigate; jumped the windows closed via the connector in the door post/footwell and she's gone off with it until we have time to diagnose further.

20 odd yrs since owning a 200, Iirc the links are fatter than the standard wires and also quite long, if blown a normal fuse must be okay to use

 

[Prajna]

@AKN yeah, motors work happily with 12v direct, and door looms fine as well, so something amiss between the switches and door pillars. I don't think it's been laid up but don't know its history prior to Nina buying it a few months ago. I measure high resistance most places; with 12.4v at the battery I'm finding, say, 12.1 at fuse C1 and 11.8 at the window switch, 0v in the door pillar connector (with window switch on). Neither window works, so something amiss between centre console and door pillars. There are a bunch of relays in front of the pillars behind a panel in the footwells but I don't see SK, SU or SR, SK wires running to any of them. Damned shame there's no Rave for that year, only scam manualsonline pdfs. I did lots of searching on the landy forums but it seems they all have later Disco 1s. We hope to get this landy up to scratch so I guess we'll just have to invest in a WS manual.

@OJCar it's a 200TDi.

 

[OJCar]

The only difference in the wiring for the 200TDi is the under bonnet engine loom so will not affect the windows.

 

[slim_boy_fat]

but don't know its history prior to Nina buying it a few months ago

Presumably in a private sale? Otherwise take it back and get garage/trader to fix it?

 

[Prajna]

The only difference in the wiring for the 200TDi is the under bonnet engine loom so will not affect the windows.

Difference between the 200TDi and what, OJ? The later Disco 1s have ECU, even separate ECUs for the window controls, so completely different wiring throughout.

 

[Prajna]

Presumably in a private sale? Otherwise take it back and get garage/trader to fix it?

Yeah, private sale.

 

[AKN]

@AKN yeah, motors work happily with 12v direct, and door looms fine as well, so something amiss between the switches and door pillars. I don't think it's been laid up but don't know its history prior to Nina buying it a few months ago. I measure high resistance most places; with 12.4v at the battery I'm finding, say, 12.1 at fuse C1 and 11.8 at the window switch, 0v in the door pillar connector (with window switch on). Neither window works, so something amiss between centre console and door pillars. There are a bunch of relays in front of the pillars behind a panel in the footwells but I don't see SK, SU or SR, SK wires running to any of them. Damned shame there's no Rave for that year, only scam manualsonline pdfs. I did lots of searching on the landy forums but it seems they all have later Disco 1s. We hope to get this landy up to scratch so I guess we'll just have to invest in a WS manual.

@OJCar it's a 200TDi.

If you put a separate feed to the terminals in the switch connector, switch removed, do the windows opperate? IF not measure the resistance, Ohms, between each connection at the switch and the other end of the wire at the door pillar connector, you need to do this for every connection as both the supply and return go through the switch. If your D1 is like my RR’s then the relays in front of the door pillar are for things like heated rear window, auxiliary lights, headlights etc. If you are going to be looking after this vehicle long term I’d recommend the link above for the genuine LR manual.

The only difference in the wiring for the 200TDi is the under bonnet engine loom so will not affect the windows

I think this is referring to the different engine options TDi/V8/mpi as the changes with model year revisions can be significant.