Thread: S3 wiring diagram

Sorry Neil can't help you with that one, I had same problem with my MGBGT using same brand of harness had to use multi meter to work out where things went, I also found the terminals very soft & they would work their way off the terminals on the switches & gauges, ended up replacing all the terminals after they came off the ignition switch & light switch. Chose an Electro Loom harness when I did my S1 which matched the WS Manual diagram & they also sent a diagram for the add On's.

Thanks Wayne.

I had heard various tales of grief involving the new looms but that’s what I’m working with for now.

It’s all nicely packaged etc - my challenge is reconciling what the various wires are really for.

One example is the rear harness which I thought would be a simple place to start. It’s reasonably intuitive which end is which and where the left and right branches are - just that the wire colours are all over the place including a majority that bear no relationship to the manual.

I guess one early route is to ignore the manual and look up a standard wiring colour guide to get an idea of what the new wires might be. From that it’s a matter of attacking the rest of the harness.

An area that I’m not looking forward to is reconciling where some extras that weren’t on my truck originally fit - brake failure light, hazard lights, two speed wipers, auxiliary socket, radio etc. These are meant to be incorporated into the new harnesses which will add another layer of complexity into the task beyond working out the colour pattern for what was originally there.

Early days.

Cheers,

Neil

Neil,
There are standard Lucas colours but I'd thought Land Rover would have used these.

Lucas wire colour codes for Land Rover


Colin

Hello again.

I’m envisaging that this could become a very long thread given my several hours spent so far staring at the various new and old loom components, colour guides, wiring diagrams etc.

In order to at least claim some progress I threaded the rear harness through the chassis late this morning after completely going over the workshops wiring diagram again earlier this morning. Apart from noting that one of the large rubber grommets is missing from the harness and the apparent inclusion of a couple of redundant wires (pink, green/brown trace) and a red/yellow trace rear fog lamp wire there appears to be no reverse light wires going to the back - I guess I can use one of the redundant wires for that if I can work out where else in the harness they are also being directed that might be important. There’s no independent number plate wire on this part of the harness either but I can take a wire off the right tail lamp connector that also serves the trailer plug loom.

One puzzle that I’m still mulling over is the white/green trace wire that is in the same part of the harness as the green/black trace wire that branches off and leaves the rear harness before it enters the chassis near the footwell. The green/black trace wire is the fuel sender which is the same as the single wire of the same colour and function as that on the original harness. The colour charts don’t list a white/green trace wire and I note that it uses the connector point on the block plug to the main loom that is sealed off and not used on the original harness. I am hoping that this might be an electric fuel pump lead but on the official workshop manual diagram for 2.25 and 2.6 litre petrol engines that wire is shown as white only. Whatever it is it must go to something close to the tank sender because it shares the same wrapping as the sender wire and the terminal is only about 30mm from the other terminal.

Anyway, I’m usually not bad on jigsaws, crosswords, unraveling tangled fishing line and, otherwise, solving puzzles. However, this one is definitely a challenge - not being an auto electrician probably doesn’t help either.

Cheers,

Neil

Afterthought - just kicking myself for pulling out the wire that I used to pull the rear harness wires through the chassis. Probably should have left it there to use for the reverse lights….

Hello again.

From the perspective of someone who likes to think he has some familiarity with Series 3 Land Rovers, if not a few of older age, I’m almost embarrassed asking this question.

Where is the temperature sender unit on a 2.25 litre petrol engine whose birthdate could be anywhere between 1969 and 1975?

Mine has an otter switch on the front left hand side of the head near the thermostat housing - it even has Otter printed on top of it. I’m assuming rightly or wrongly that this is an on-off switch that helps to regulate the choke warning light by sending a signal to the speedo binnacle in conjunction with the switch on the choke cable.

However, look as I may I’m not finding another temperature sender switch anywhere else including in the place on the front right side of the head also near the thermostat housing where the workshop manual suggests it should be. There must have been one somewhere on the motor because the truck has a temperature gauge in its instrument cluster and it once worked. Unfortunately, I disconnected the various wires some time ago figuring that refinding the various connection points would be fairly intuitive.

So, correct me if I’m on the wrong track here but have I got that correct - the otter switch has nothing to do with the temperature gauge and there must be a variable sensor somewhere on the motor? If that’s correct then repeating the original question - where might it be?

Cheers,

Neil

I'm pretty sure the temp sender unit on both SII and SIII 2.25 engines was on the thermostat housing. As I recall, the choke light was just that: a light to tell you that the choke cable had been pulled out! When I get a minute I'll check my manuals.

Temperature sender is on the right lower side of the thermostat housing, screws in horizontally. The thermal switch on the left side of the head next to the thermostat housing is, as suggested, for the choke warning light.

Originally Posted by JDNSW

Temperature sender is on the right lower side of the thermostat housing, screws in horizontally. The thermal switch on the left side of the head next to the thermostat housing is, as suggested, for the choke warning light.

John,

Yes, that’s been my understanding of the apparent arrangement. However, and I’ll need to check this again, I haven’t actually been able to locate anything on that lower right hand side of the thermostat. If it’s there then it’s well camouflaged.

Cheers,

Neil