[Jb10000]

Hello Everyone,
I have a defender 90, swapped a 4.0V8 from a p38 ranger rover, I removed the immobilizer, can someone help or direct me to a wiring diagram so I can run the ECU without the BeCM, I want to reduce wiring I just need the ECU to run the engine that's all.

Custom harness to run the ECU standalone

Thanks.

 

[One Ten]

This is for a disco 1 4.0 GEMS but should be the same if you are using an early P38 with a GEMS engine. Your ECU will need an “F out”. done though. That turns off the alarm/immobilization. I used to be able do that, but don’t have the equipment for it anymore. I’ve moved on to LS engines

 

[Jb10000]

The immobilizer has been removed from the ECU, do I use the p38 fuse box or? That's what's confusing me

 

[Uncle Douglas]

Haven’t done one with a p38 harness. D1 also has an underhood fuse box & we do not use those. We don’t retrofit any of the evap stuff either.

 

[Jb10000]

I do have the ECU unlocked, i can make a custom harness with what I have I just need to know what wire goes where from the ignition switch to a starter relay to run the engine that's all I need, do you think you might have a pic or something that can direct me to wire this thing so it runs?

 

[Uncle Douglas]

I do have the ECU unlocked, i can make a custom harness with what I have I just need to know what wire goes where from the ignition switch to a starter relay to run the engine that's all I need, do you think you might have a pic or something that can direct me to wire this thing so it runs?

I typically reuse/ modify the original defender harness so that I have the plug that mates to the defender main harness. I splice the oil pressure & temp gauge wires from the gems engine harness to the defender loom. The starter solenoid wire from the original harness and double brown wires that power the truck from the starter lug remain as well. FWIW a 300tdi temp sensor/gauge sending unit screws right into the gems manifold and is the correct resistance to work with the original defender temp gauge.

 

[Jb10000]

I typically reuse/ modify the original defender harness so that I have the plug that mates to the defender main harness. I splice the oil pressure & temp gauge wires from the gems engine harness to the defender loom. The starter solenoid wire from the original harness and double brown wires that power the truck from the starter lug remain as well. FWIW a 300tdi temp sensor/gauge sending unit screws right into the gems manifold and is the correct resistance to work with the original defender temp gauge.

Oh yes that is much easier, however I only have the engine harness, fuse and relay box, ignition switch all from the p38, my land rover 90 does not have any wiring it was just a shell

 

[M.A.R.S.]

On the gems stand alone harnesses I have done it has always been d1 donor parts. The p38 has an electrically shifted transmission. Are you using that as well? Was thinking engine harness has the transmission harness made into it. But I could be wrong. Also thinking the p38 gems ecu will be looking for input from the transmission ecu. I have always had issues using the p38 components functioning correctly.

 

[Jb10000]

On the gems stand alone harnesses I have done it has always been d1 donor parts. The p38 has an electrically shifted transmission. Are you using that as well? Was thinking engine harness has the transmission harness made into it. But I could be wrong. Also thinking the p38 gems ecu will be looking for input from the transmission ecu. I have always had issues using the p38 components functioning correctly.

I have changed settings of the ECU from automatic to manual transmission, there's too many wires that's why I want to simplify it since the ECU has been set to run independently from the BeCM.

 

[Uncle Douglas]

Oh yes that is much easier, however I only have the engine harness, fuse and relay box, ignition switch all from the p38, my land rover 90 does not have any wiring it was just a shell

Man you’re going to be busting some rocks. Part of what makes this conversion easy is how rover color codes wiring and really didn’t change things across the model lineup.

 

[Jb10000]

The issue is I have no idea where to start, what goes where do you have the wiring diagram for the ECU

 

[M.A.R.S.]

Do you have the engine installed in the defender? Harness attached to the engine? Any pictures of what you have? Are you set on using the p38 set up? Normally the p38 harness exits from the front side of engine block. The discovery exits near the rear. Do you have plans on locations of mounting the ecu?

 

[Jb10000]

Do you have the engine installed in the defender? Harness attached to the engine? Any pictures of what you have? Are you set on using the p38 set up? Normally the p38 harness exits from the front side of engine block. The discovery exits near the rear. Do you have plans on locations of mounting the ecu?

Here's everything set, how do i wire the ignition to run the ECU to run the car