Hi , I have just bought another 40 , ( 1990 ) and am working my way thru a few small issues , the most annoying one is a constant buzzer noise once the lights are turned on , this happens with the engine running or not . Can anyone help me out here . Thanks Mark

 

Do you mean "buzzer noise" as in the "lights left on, key out" buzzer? If so maybe theres a loose wire at the key switch?

 

The diagram of the circuit for the Lights On Audible Warning Module (LOAWM) is shown below. It doesn't make it obvious how the circuit works, but it seems like the if the switch in the Lighting Logic Unit is closed when the key is off, the audible warning sounds. The Key Switch is shown as normally closed, and the switch in the Lighting Logic Unit is shown as normally open. The wire from the LOAWM to the Key Switch is Blue with a Red tracer stripe (color code UR). The wire from the LOAWM to the Facia Switch Pack is Blue with an Orange tracer stripe (UO). The LOAWM is located behind the left dash knee bolster/underpanel.



You can download the wiring diagrams at the link below:

Jaguar XJ40 Electrical Guide 1990

Cheers,

Don