Apr 012013
 

As I’d spent many days meticulously labelling the new wiring looms using both the service manual and Coventry Auto Components diagrams and all the connections were accounted for, I foolishly assumed everything was correct. All that would remain would be to connect up the looms to each other and the corresponding components.

However I hadn’t checked back to the original loom … until now. The two looms are completely different for the connections to the starter solenoid relay, mounted on the engine bay bulkhead.

The relay connections on the new loom end close to the join between the dash loom and the RHS body loom, circled in Red in the photo. The ends are terminated with female spade connectors suggesting the relay is attached at this point.

However 1) there’s not sufficient length to route into the engine bay and 2) there’s no suitable exit hole near the relay into the engine bay.

So I can’t see how to route the new loom to the relay mounted on the bulkhead.

Where the new loom ends with the relay connectors, the original loom has both the larger current carrying wires for the relay (White/Red and Brown) wires cut, only the switching White/Yellow wire remains. The other end of the brown wire exiting the loom near the ignition switch is similarly cut. As both cut ends appear to be properly taped it could quite possibly be a factory modification, made retrospectively to looms that had already been delivered to Jaguar.

Current carrying wires cut

Brown ignition wire cut

I’ve not located the other end of the White/Red wire yet due to a slight mishap with a Stanley knife while cutting away the taping on the old loom. I’ve found the braided wires to be quite absorbent and the claret colour of blood does a splendid job at hiding the colour coding! Lesson re-learnt: cut away from fleshy bits, not towards!

The relay was connected via its own separate loom, which also appears to be original (right). The routing of the White/Red and Brown wires, cut in the original dash loom, is directly between the bulkhead relay and the starter motor, ie doesn’t enter the dash area.

The switching White/Yellow wire is contained in a spur with sufficient length to reach the dash area from the engine bay via the hole high in the transmission tunnel panel.

So my current thinking is that this was a factory modification to keep the current carrying wiring away from the dash. Only the relay switching wire carrying a low current is routed into the cabin area.

I suspect this change may have been made during the S2 production run as I’ve not found any of the usual suppliers who sell a separate starter solenoid relay loom. I will have to ask Autosparks to make up a loom based on what remains of the original. The other issue is the original loom had a White/Blue wire connected to a central terminal on the relay. There’s no reference to a White/Blue wire in any of the wiring diagrams so I’m stumped what it is for at this stage.

I’ve subsequently found out that it was a factory modification after all. From chassis number 1R1393, just 28 cars before mine, a ballast resistor was introduced and the relay moved to the engine bay bulkhead.

The starter relay was changed so that it could switch two circuits – delivering power to the starter solenoid and bypassing the ballast resistor. The white/blue wire enable the ballast resistor to be excluded from the circuit on start up, increasing the current delivered to the coil.

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