Conflicting info from local sources... ISSUE:
Told there is a relay that controls smooth shifting. I get an intermitent trans warning light when relay doesn't work. If I shut car off and restart, it will turn off the warning light and resume smooth shift for a while.
1st tech told me it's the relay attached to the shift assembly on the left side, access by lifting the "ski slope" The relay is no longer available new, forcing me to buy used with warranty. Bought 2 just in case. Neither solved the issue.
2nd Tech told me the schematic shows it in the R/R wheelwell. The schematic did not show relay attached to shift assembly! Said it is a regular 4-pin relay, available anywhere. He said access is thru the trunk with removed.
So...question is with panels removed there is no relay in sight. Wiring disappears in upper right corner, behind the black metal panel covering the fuel panel with 18 bolts! Do I unbolt the black metal panel hoping its there, or pull the rear wheel and wheelwell panel to find it?

 

There are about six relays behind the black plate.
If I kept my cars I was going to relocate them to the inside of that plate.
On my 94, 6.0 coupe three of the relays were for the fuel pumps.

 

XJS-XKR,

The components were moved about depending on year and model. You haven't said if you've got a 5.3 or a 6.0, or if it's a Coupe or a Convertible?

Look at the electrical diagrams here for the 1993 & 1994 models: JagRepair.com - Jaguar Repair Information Resource

In the early part of the electrical diagrams for each year, you'll see the locations of the relays. On the face of it, it seems that the 5.3 3-speed boxes have a Transmission Power Relay, as well as a Transmission Warning Relay, whereas the 6.0 4-speed boxes don't seem to have a Transmission Power Relay.

Hope that helps

Cheers

Paul

 

Paul
I have a 93 6cyl convertible. A reply says there are 6 relays behind the black metal plate. How do you identify the relay for controlling smooth shifts and test it if it is working and all are black?

 

Paul,
I said about six relays , that might not be accurate for your car.
Actually, they might not all be relays, on my 94 V12 there were three fuel pump relays.
There are items that might be referred to as controllers or modules.
You must get the owners manual for your car.
They have a page that maps out what and where all these things live.

 

XJS-XKR,

I'm no expert but know a reasonable amount about XJSs. So please indulge me whilst I share my thoughts.

The relay to which you refer does not control "smooth shifts". All the shift points etc of the autobox are controlled through the gearbox ecu. That relay is "merely" allowing power to flow to the gearbox ecu.

I'm guessing that your original problem was seeing the gearbox warning light illuminate? That's a symptom of a gearbox problem OR another problem on the car such as an engine error which has put the gearbox into Limp mode. You can often tell the difference by whether the gearbox stays stuck in one gear or whether it operates up and down all of the gears but less smoothly. If it's stuck in one gear, then that is Limp mode and the problem almost inevitably lies somewhere other than the gearbox. If it is a gearbox issue, it could theoretically be a failing power relay, but I've not heard of that before (which isn't to say that it isn't happening!) Who was it that told you it was the Transmission Power Relay and how di they conclude that?

As mentioned, the relay components were moved around in differing years. If you use that link I posted and go to the 1993 XJS electrical diagram, Page 11 seems to indicate that the Transmission Power Relay is behind the storage panel behind the seats on the left side in a Convertible. And then Page 65 shows the wiring diagram of the componnets. Of course, that may not be correct, but Page 11 shows only 2 relays behind the right hand rear wheelarch location for a Convertible. I'm not sure which relay you found and changed under the ski slope. That electrical diagram doesn't seem to indicate that there is one there on a 1993 model?.

I hope that helps a little!

Cheers

Paul