A quick recap: Chasing an Engine Fault led to a failing P/N switch, confirmed via back-probing the G wire off of the rotary switch. So I opened it up, and well well well... lookie here; this is after I already cleaned the back plate. It was absolutely caked in white:



I am spraying the snot out of it with WD-40 Electronic Contact Cleaner. After spraying, here are the backing switches, a close-up:



I hesitate to attempt mechanically cleaning these, as I would rather not risk a reduction their spring action. I'm considering different methods, perhaps a baking soda & water solution, or perhaps even a bit of Diet Coke or something; I am fairly certain the white-cake corrosion plus the copper / green corrosion has led to inconsistent contact. What is a mystery still, is why this would be the case only after a significant driving period, but clearly this corrosion is an issue.

What do you all think for the best method to clean / refurbish this unit?

 

I would start with a tooth brush and WD40.
Might have to go to baking powder and tooth brush, washed out with WD40.

 

I have known ignition switches go on fire after being squired with WD40 ( Spark) and its 10 % oil so stick with the contact cleaner and dry in an oven at 40 c before you re fit it.
I think you are going to end up changing all the switches.
If N/A in US I can look in UK and post. or whole unit from jag spares

 

Ugh. Looks like it's been waterlogged at some point.

Agree with pb that those switches would be best changed:- I'm surprised that it's only the P/N one that's playing up. There appears to be a part# embossed on them so you have some hope of finding replacements.

 

+1

You may get it WORKING but getting it RELIABLE could be a step too far.

Graham

 

Those transmissions were used on so many different makes and models of cars, it must be possible to find one in a junk yard near you, even if you had to re-wire the connector or transplant the micro-switches its going to be a better option than trying to revive that basket case.

 

not how it works. jaguar l1-l4 chart is totally different

tons of ones from a jag on ebay

 

if you need parts shipped from the UK let me know

 

You mean the microswitches are different?

 

You could try soaking it in white vinegar for a few hours, then washing it off with water.

 

If you have one lying around, sure, but Don’t want you to go to too much trouble.

I did fit the part today, but no good. Pulled it and soaking in vinegar for a day, we’ll see.

Think those switches will be tough to pull and replace without cracking all that ancient plastic

 

did find this one today on UK ebay but at £168
ROTARY SWITCH / AUTOMATIC GEARBOX SELECTOR - Jaguar XJ8 XK8 1996-2002 | eBay

Seems the one for the xj8 is the same ..I found one at £128

Auto reserve wont ship to America but they will ship to me and I could DHL it to you. Air mail is very slow.
UPDATE
Found loads on US ebay at a bout $200 some with free shipping from the UK

 

Yeah, I was considering used via Ebay as last resort if these are known to fail. But I did manage to find one that has a return guarantee. So I'll go for that. Thanks for your offer anyway.