I had my jaguar Series III in for servicing recently as I could not identify why fuel was not getting through. A circuit was found to be the issue - that was fixed. I got the car back only to discover that the wiring in the boot that activates the diode that manages the dual fuel tanks was not connected correctly (neither was the aerial). I am looking for some advice before I simply plug wires back in (given that its power and fuel related).

The power source comes in to splitter of some sort. My question - can I simply just plug the diode in to any available slot/position or should I be more cautious than that?

Thanks T

 

what year is your S3, you talking about dual fuel as in petrol/lpg? if it's LPG - is it setup to auto switch to LPG after startup?

 

Hi xjtom - thanks for your help. Its 1983 Series 3 and its petrol

 

when you said dual i took that to be 2 types of fuel not tanks....what was the original issue and how was is fixed, are the tanks switching over ok now?. can you post what the wiring colours are for the diode unit & the connecting plug you want to reconnect to also how was it not connected correctly?

the schematics i have doesn't show a diode

 

There is no diode back there. The switchover valve has a 12v+ wire and a ground wire. Can you post some photos? One showing where it is located in the boot and another close-up of the wires/connectors in question?

 

Yeh - there is a diode connected to this relay - I just unsure how to reconnect the wires.

 

If you are referring to the black cylindrical end on the UW wire, that would be the female side of the wire connection, the male side is shown laying beneath the UR wire in picture #1. This is the "up" wire for your antenna, just plug the two together.

Dave

 

CanberraJaguar,
My last post may not have been the most helpful, here is a schematic of your antenna relay.



Connected on your relay, I can see a B wire, UR wire, and maybe a P wire beneath the UR wire. I see what looks like a W wire, but is probably the WK from the radio, this one should be connected to the relay spade opposite the B wire connection. The UW wire with the female spade should be connected to the relay spade just above the UR connection. After that, I see a pair of UW and a pair of UR wires with mating male/female ends and I would think they should be plugged together. You'll notice the B to the relay is also connected to the ground for the fuel solenoid.

I hope this helped a little more.

Dave

 

C - this photo shows the relay that I 'think' I have wired correctly now.

B - This photo shows the 2 black wires coming from the diode that assume connect to the 2 black wires in Phot a that terminate together?

A -This photo shows the spare/extra wire that I cant seem to find a connection for. It looks like it has broken off something but I cant see what?

 

The white/purple (WP) identified in picture A is the 12v source for the "change over valve" shown in picture B. This might be where some of us are scratching our heads when you say there is a "diode" there. Here is a picture of an early layout of my fuel system in the boot, including the change over valve. You can see that I have labeled one of the B leads as WP and would connect to the WP in your hand, picture A. The other B lead goes to ground. But wait, there's more.......the change over valve (COV) is a simple two-position valve that allows fuel from the left tank to the pump, but blocks fuel from the right tank or visa versa depending which tank you've selected with the switch on the dash. In the "normal" ignition-off condition the COV defaults to the left tank and blocks the right tank. With the ignition-on condition you can select the right tank if you want.

I believe the way I figured out which B lead on the COV to connect the WP wire to was with the key-off, dash switch to left tank, and COV leads connected to WP/B (12v/ground), have a helper put their hand on the COV and if they feel a "thunk" when the key is turned on, reverse the wires on the COV. Now, with the dash switch still in the left position, move the dash switch to the right tank and your helper should feel the "thunk" and when the left tank is selected they should feel another "thunk". A double check: dash switch to left tank and turn key on, helper should not feel the "thunk". Dash switch to right tank and turn key on, helper should feel "thunk"; select left tank and should feel another "thunk". Turn key off.

Dave