Ganner

If when starting the car the light is out and stays out until you touch the brake peddle. the problem may be you need a brake servo. the issue is the solenoids that sit on the front face of the servo has gone down. they say that you cannot buy them separate from the servo although they just screw into the servo. cost of new servo £449.00 + vat. you may have issues with the ABS system on early models this also may require changing and would need pairing together after fitting. Jaguar have the diagnostic equipment to establish this, normal garages may not have this capability. cost around £40-50. If light is on permanently same applies.

The problem may be the seal on the petrol tank has split easiest way of proving this is to fill the tank with fuel and see under the car fuel leaking on the floor. this has been a problem with Rover 75 as well as Jaguar I had mine done recently.