ABS and brake light coming on in drive

Hi, I’m new to the forum and would like some help and guidance with my 1991 XJS Convertible 5.3.
The ABS and brake lights light up when the ignition is turned on and extinguish as the should after a few seconds, with the engine running there are no warning lights ion the dash BUT, as soon as I engage the drive the ABS, brake and handbrake light all come on and having taken the car for a 20 mile drive yesterday, the lights remained on throughout.

When I got back to my workshop and disengaged the drive the lights went out again as normal.

I have removed the binacle and checked all the circuits which appear to be working fine.

Any ideas or help would be greatly appreciated.

Thank you

Hi David,

first I would download Kirbys excellent manual, theres a lot about the abs there.
second get the Jaguar ROM - theres a lot of info in there.

one question. if you start the engine, then hit a the brake a few times does the abs light come on?
the teves system is very early ABS so has some quirks and is expensive to fix, so try to eliminate each item first.

Best regards

Simon 1991 XJR-S

Hi Simon, thanks for responding so quickly. I have just started the car again and now the abs light is staying on and no other warning lights are showing.

When I engage the drive I have the ABS, brake light, handbrake light and screen wash light all on.

I’ve changed the ECU in the boot on the left hand side and checked that the pump is working correctly, we’ve bled the brakes twice and I have a good pedal which appears to brake as it should do, there is no hardening of the pedal and the car pulls up straight under heavy braking without skidding.

I have gone through a number of procedures as seen on a few forums, but am still at a loss…



As the car is 28 years old, do you know when the accumulator (black sphere) was last replaced?

They do lose pressure over time.



Hi Andy, thank you for your response, I have two spare spheres and have changed for one that is definitely okay as it came off a working V12.

I’m beginning to be drawn to an electrical issue, as the washer light is on at the same time as the abs, brake light and handbrake light only when put in gear.

I may be barking up the wrong tree, but just trying to eliminate open possibilities.


Hi, beenmessing around with the ABS problem again today.

Cleared the 21, now showing code 27. No mention of this code in the Jaguar XJS workshop manual, and can’t find a list of codes on line for the XJS ABS ECM codes.

Therefore, does anybody have a list of ABS codes for the XJS V12 Pre-facelift (1991) or are you able to direct me to them please.

Kind regards

Just found the codes here on the forum, thanks to BobboSD and TBIRD for their posts, even though it was over a year ago, well done much appreciated.