Recently got a 1995 jagaur xj6 4.0 4D sendan
guy before me did all kinds of wiring cutting etc. i have fixed just about every component.
found the old ecu like this (in images) got a new one and it didnt turn over until i rewired the wire exactly like the way the guy had it but on the new one. Turns over runs and drives perfectly fine. Once car is off after 1 min etc. it wont turn over and i have to rewire the wire and it turns back over with no problems. Runs fine then again etc. I’m thinking it’s the wiring harness just because it’s cut. But I’m also thinking the sensors it connects to. To unlock the engine to start.
whenever the wires connect a click happens every time.
the wire is also brown with light purple on it.

New ecu the only way it works. Just how the old one was.

Closer look

Here is the old one.

Insides where fried and water logged

Where the wire connects

Connects to C410

 

There are 2 ECU wires that is an enable to the BPM to allow the starter to engage

PI 104 - 20 ( light Green / Black color ) , i have the colors swapped around against the connector map below

PI 105 - 35 ( Green / Black color )

To cover a base to not be missed there is a inertia / crash switch that can act up and bypassed

Is your engine 3.2 or 4.0 liter ?

Brown / light Purple as faded Purple pin PI 104 - 18 ( NP )

This pin 18 is a ground provided by the ECU to close the ECU controled relay

This relay is your 2nd power used at all times that power the fuel injectors , power going back into the ECU , and half of your sensors

No power from the relay , no fuel injectors

To test it quickly the large # 5 right relay must click on your finger ( not by sound ) when moving the key to run before starting

 

Hi Zeo. Eunoia,

Welcome to the Jaguar Forums! It's great to have you with us.

You can download the wiring schematics that Parker refers to in his post at this link:

Jaguar X300 Electrical Guide 1995

Cheers,

Don

 

New connectors on the ECU side and car wiring side are available

They are TE Connectivity 36 ( pin ) way Econoseal 3