Guys
I need to identify a circuit on my car that has 12v power when the key is:

• in the ​​​Accessory position (position 1 on the key) AND has power
• when the key is in the run position (position 2, ie ignition is on);
• but DOES NOT have power when cranking (ie position 3, starter motor engaged).

Can anyone identify for me a suitable circuit to take power from.
Thanks
Greg.

 

Greg,

Electrics are not my strong point but I have a gut feeling that there may be something associated with the ALBS systems that might work. The attached wiring diagram shows various feeds that are live in ignition switch positions 1 and 2 but dead in position 3. Applies to a 1990 model but gives an idea I guess.

Apologies if I'm over-thinking this and there is something much easier as an option.

Cheers,
LeeP

 

Lee
Many thanks, but as my car is pre ABS it does not apply; I follow the diagram position 1 and 2 part on your diagram OK, but I have no idea if there is a circuit like that on my car.

Perhaps there is something that has feed at 1 and 2 and not at 3 on my car, but I cannot fathom the diagram I have, so that is why I am appealing to the forum.

Thanks for trying!

 

It gives me a headache, but it looks like the White/Pink wire on the ignition switch has what you want. That's what I can gather from the pre-86 diagram of the ignition switch wiring. It appears to control the load relay, fuse 5 on the main panel, the power window relay, and some others. It looks like it is deenergized with the key in the start position.
There are other wires that color, so be sure to get the correct one.

 

Greg,

I don't have access to the wiring diagrams for the mid-80s cars. However, just in case there is any consistency with the late facelift cars, this may be useful:

On the late cars, You have electrical circuits as follows:

- Those that are always enabled
- Those that are enabled when the ignition is in Pos 1
- Those that are enabled when the ignition is in Pos 2 (remember some of those are "carried forward" from Pos 1.
- Those that are enabled when the ignition is turned to Starter Position (Pos 3) (some of these are carried forward from Pos 2, but NOT from Pos 1)

On the late cars, when the ignition switch is turned to the Starter Position, the circuits which had only been enabled by the key being turned to Position 1, are then disabled.

So, IF the logic works the same on the early cars, then you need to work through which circuits become enabled only when you turn to Ignition Pos 1.

BUT, the early cars might not work the same!

Hope that MIGHT help

Paul

 

The earliest .pdf Jaguar publications are for the 1987MY sedan and XJS.

S57_2.pdf is the publication to see if it will work.(1987 MY XJS close enough for 1985?)
Earlier electrical guides will have to be '3 ring binder' paper documents.

 

That document is the one I referenced. It says "thru 87". It should be very close to an 85.

 

Jal
Thanks very much, I will test that and see what happens. I do wonder if the load relay is denergised during cranking how the fuel pump etc works. Anyway, testing will see!

I will also try to follow the diagrams kindly posted by Motorcarman

 

Just tested, AND thanks to you all, YES the white/pink wire from the ignition switch IS live on position 1 (accessories) and position 2 (ignition) and is NOT live in position 3 (start).

I tested it as follows:
The white/pink does the windows and the load relay according to Motorcarman's fantastically clear electrical diagrams, for which many thanks. In P1 the windows work, in P2 the wondows work, BUT in P3 (while cranking) the windows do not work. Therefore no feed during cranking to anything fed by the white/pink.
This wire goes to fuse 5 which on my car is indicators, brake light switch and kickdown switch. So I can pick up 12v from the feed to the brake lights and be wure it will not be live while cranking. I am in the process of fitting an Dakota Digital cruise control to my car as the OEM system is not working, and ideally (though it probably does not matter in practice) in order to protect the system from spikes in the voltage it should not be live during cranking.

I am very grateful for everyone's help, many thanks again.

 

I'm glad you found that the white/pink wire worked. I was about 95% certain it would, but it all depended on my interpretation of how the ignition switch worked when rotated from the wiring diagram. I stared at it for a long time!!
Jon