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300tdi into 90 4C wiring puzzle

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Hi, I've bought a project 90 4C with the engine already removed, it came with a disco 300tdi to put in it (with the back plate already modified to fit the LT77)

It was missing the engine harness so I've bought one off ebay, I also bought a glow plug relay (with wires attached) from ebay too. That's what's puzzling me. I've found this helpful diagram.


My 3 is red/brown not white/red and my 4 is black instead of white.


In the 90 I have 4 leads near where the relay should be mounted, I've identified the thick 12v from the battery but the others are puzzling me as the colours don't match the relay ones, I've got.

A set of three with round connectors Brown Black Green

A set of two with square connectors Yellow/Black Black


A set with square with a cross connectors Green/ Black Black

Any ideas? Any help greatly appreciated. Thanks.

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the oblong connector with two males and a female connector is a mystery to me too. i have the same hanging in the engine bay by the bulkhead. mines not ever been connected, so i'd ignore it for now. LRs have plenty of redundant wires. you can put power to the truck and put a tester on it. if its live you can pull fuses until the tester goes off.

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IMG 1667

this is what i have. there should be a connector block coming out of the bulkhead immediately behind the engine. there are similar blocks coming out of the bulkhead by the drivers side.

the colours on the conector coming out of the bulkhead for the glow plug relay should correspond with the wire on the relay.

i have , black, yellow, white, white/red

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Off topic, but were is the nomenclature of "4C" coming from for Land Rovers???

Wouldn't worry about the glow plugs, Tdi's will start without them pretty much. If you find you need them, it's just a 12v feed. So easiest way is wire them in direct yourself with a momentary button of your choosing (and maybe a relay ;) ). No need for a timer or anything complex.

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i have two copies of the Haynes book of fairly tales. one covers 1983 to 1995 and

corresponds to the wiring i set out above, but the other book 1983 to 2007 is different. although they cover the same vehicle.

so: in the later edition it says:

brown/red =1 main power from starter motor ( thick wire )

black / yellow = 2 to glow plug warning on dash

green/ yellow = 3 goes to the ignition switch 1 ( 1st turn )

black = 4 goes to earth

brown = 5 goes to the fuse box / ignition switch 2 ( 2nd turn )

yellow / black = 6 to glow plugs ( thick wire )

BUT as said earlier. theres more ways to skin a cat as the Chicken drummer said

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4C = 4cylinder engine.

have a look in our tech archive for 'defender 200tdi retrofit fitting' I added these a while ago, it gives info on how to connect the glowplug timer to the pre tdi engined vehivles.

green/brown trace is reverse light wiring from gearbox switch to rear of vehicle.

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