- XJS Forum -

'93 XJS Brake Lights

daniel elliott
Pacific Jaguar Enthusiasts Group *

forum user since 2011-04-08


The Brake Lights on my '93 decided to stop working. The third light works just fine. The bulbs are good, grounds are good, swithch is good, fuses are good.

The dealer says it is a control module that is no longer available - ordered a used one.

Anyone know of a mod or update to the system that will eliminate the need for a control module?


93 XJS 4.0

'93 XJS Brake Lights

William Brady
Jaguar Owners Club, Inc. *

forum user since 2004-02-15


I would check the "power units" behind the rear lights & i believe the feed comes fro the electrical area under the passenger (Right side) knee panel.

Jaguar affectionado and etc.

Re.: '93 XJS Brake Lights

Tim Charron
on Member *

forum user since 2012-06-26


Edited on 2012-06-26 9:05:05

My '92 XJS Coupe had the same issue when I took it out of storage last year.

I traced the problem to a faulty brake relay (the blue type) located in the left trunk wheel well (you may have to remove the metal 'wing' in there to access it). The horn relay is located more conveniently under the hood on the passenger side (behind a small panel), and I was able to swap these relays to confirm the problem (brakes started working, but horn stopped).

I recall that I was able to 'prove' this was the problem and not the brake light switch or the lucas units by using the cruise control. If my memory is correct, a bad switch or lucas unit would also cause brake lights to fail, but it would also mean that the cruise control would not disengage automatically when the brake is hit. A short drive confirmed for me that the cruise could be disengaged by tapping the brake, so not a switch or lucas problem. Sorry I don't recall exact details but this can be checked from the wiring diagram.