Hey all - brand new Jag owner and new to working on cars generally. Really want to learn though. I just got a 92 XJS v12 from my deceased grandfather. Everything seems to work except when I went to put down the top, nothing happens. I’m told the mechanism worked 6 months ago when they put the top up. I’ve tried the emergency brake thing. I really just want to put the top down any way I can and probably leave it down indefinitely.

Any tips where I should start? Fuses and relays? Go straight to manual? Appreciate any advice.

 

To put the emergency/hand brake pull the leaver up a few notches, the brake warning light will come on. Put the car in P or N and press the switch. I find it better to have the engine running, To release the brake Push in the button and pull up, still holding the button let it go down then release.

 

I tried that and still no luck. I do notice that the brake light indicator doesn’t come on. I think I’m using it correctly too.

thoughts?

 

There is a manual over ride on the pump in the box behind the seats.
That will allow you to manually put the roof up and down.

If the hand brake light is not coming on then the micro switch is not working, the light needs to come on for the roof to work in auto.

Must be in park, hand brake on for the roof to work in auto mode.

 

The flow of power is through the relays, so it's possible one contact of the relay is burned - that's a reasonably common occurrence. If you replace all 4 relays you should get heavy duty 40 amp relays, 30 amp won't work.

 

this is awesome. thank you.

I was able to manually put the top down which is great. However the back windows are still up. Seems like I have 2 options. 1) fix the micro switch so that the light indicating the hand brake is on works. Or 2) is there a way to manually lower the back windows?

 

I did take off the 6 relays and clean each of them hoping that would work but still no go. Should I replace them? They actually all looked really good. Thank you!

 

Take a look at jagrepair.com and get yourself the electrical guide for the 92, and then you can see the power flow. I wired my top module to operate with the handbrake off, you might try running a temporary wire to bypass the handbrake switch and see if that is your problem. https://www.jaguarforums.com/forum/x...6/#post2090470

If the top still doesn't move, then test for power at the relay sockets and verify they are good or bad. Last is the roof switch but those can be swapped for a window switch for testing, they are the same electrically.

 

Also if its its switch itself, they are pretty easy to open up and clean out the carbon build up. You can also do the ground wire mod so you dont have to use the handbrake to lower the top. It may be worth trying that just to see if it works just by taking the brake out of the equation

 

that sounds like a good idea. Again, I’m a novice at working on this stuff, especially wiring. Could you tell me where on the car to find the switch? Is it the left panel under the dash?

 

This ^^^^

Finding and dealing with the switch for the Brake and dummy light on the dash sounds like where I would start digging. If the light on the dash isn't lighting there is a high probability that the ECU or relays (actually I don't know which part of the system the ebrake signals) aren't being grounded to power the pump...

If no joy there, check the switch itself. Is yours on the center console?

Check to see that there is fluid in the pump and it's condition. If ya find a mess of oil dry or wet, there is a simple rubber seal (which is good practice) to replace. Found in the innerdz of the pump.

Someone here should be able to tell ya how to hot wire that pump or delete the need for the signal from the ebrake...

You're in a good spot, Brother!
Let's see a pic of that CAR!!!?

 

By the switch I meant the top switch itself. As for the wire to ground its at the pump itself. Heres a link

https://www.jaguarforums.com/forum/x...6/#post2090470

 

Brilliant! ^^^^^
On my to do list.
Thanks, TIR...

 

No problem! Its been around long before me, but it is definitely worth the time doing it, and if you do it right, you can always put it back to factory without any trouble. Its really nice to just hop in, start the car, unlatch the top, lower the windows and top and go! I must admit since i did the mod, i haven't used my parking brake at all!

 

There is also a blade fuse on the relay panel. As its a '92 do you still have the box or have the relays been moved into the boot ?

 

l'm curious about this would like to modify my 1989 Xjs to do this my relays are in the box

 

the panel is in the box behind the seats, not the boot.

 

I’ve tried unsuccessfully to ground the brake wire thing following the link people have sent me.

I then learned from my uncle that my grandpa was getting annoyed by the brake light which would stay on so he had my uncle disconnect it over the winter. Apparently this is located under the drivers seat. My problem now is that one of the 4 bolts holding the seat down is stripped and I can’t get it off. I’m wondering if my brake wire grounding doesn’t work because of the wire my uncle disconnected.

I just want to get the damn rear windows down! Haha.

any help is very appreciated

My brake wire grounding attempt

 

Check that the plastic connector is actually making contact with the Jag wire......sometimes they don't !