XJS-V12 Brake problems

[French Novice]

Hello everybody. I have a French friend who has a problem with  the brakes on his 1989 XJS-V12. The car has only done 63,500 kilometres and is a lovely example. Ubnfortunately he does not speak English so has asked me to try to find the answers to his problems. The brakes are ABS (make ATE).

1) The warning light comes on when the pedal is depressed (staionery or moving). Bothe rear lghts operate correctly. Why?

2)ABS warning light comes onn even though the ABS sensors have been replaced

3)Diagnostic codes 21 and 76 (front right wheel sensor fault)

He asks,what can be the problem and how to correct the faults

Where is the main solenoid valve located?

How can he open the solenoid valves on the ABS ( make ATE) so that he can bleed thge system?

If you are able to help with any of this please e mail me on barry.oversby@gmail.com.

Thank you for reading this post and any help you can give will improve international relations. Ha ha.

Cheers 

Barry