Different headlight issue.

[gruffalo]

Headlights have taken on a mind of their own, come on for a while then go off and the MIL light comes on then they come back on for a bit and the MIL light goes out, if I try and turn the headlight soff and back on they will not come back on until the MIL light goes out. The car meantime is running brilliantly.

I have HID lights so the control box in the boot does not handle any current as that goes via a separate fused relay and the box in the boot just controls the relay.

Earthing problem, just wondered if any one had come across this before?

[Tanguero]

What if any fault is being logged when the MIL light comes on?

[gruffalo]

Not been able to look at that yet, but I do not believe there is an ECU issue.

[FarmyardPants]

What Tanguero means is that the ECU controls the MIL light. If it lights up, there should be a fault logged in the ECU which might help you trace the problem.

Might be worth checking the boxes in the boot for signs of trouble (see other thread)

[Jabbah]

I have had this when the battery is flat and I try and jump start it but haven't made a good connection with the jump leads. Sometimes the lights will come on whatever you do with the switch. I have HID lights on a relay too. Pressing the red button and starting again fixes it for me though.

[gruffalo]

Thank every one, checked the boxes in the boot and all is well in there.

Where does the ECU earth to and does the headlight circuit go through the control box behind the dash and if so where does this earth to?

It must be something common between the ECU and the headlights but obviously the headlight circuit does not go through the ECU so earth is my thinking.

[Tanguero]

Its also possible that there is a loose connection somewhere in the wiring for the MIL light its self and the ECU is not switching it on. If that is the case then it would seem feasible that whatever loose connection is interfering with the headlights may also be shorting out in such a way that current id unexpectedly going through the MIL light circuit. That may give you some hints for tracking down where the problem lies.

[gruffalo]

Well after a full day with the car in bits could not find any problem so put the car back together took her for a spin and all worked perfectly, I think she just wanted some attention.

[gruffalo]

Looks like it may be the alternater, I thin kthe voltage regulater is on the blink, interesting issue I am guessing that the light turn off as the ballasts are shutting down to protect the bulbs and the MIL light coming on is the actual problem, problem is tha tevery time I seem to get time to drive the car it is either dark or foggy so head lights are always turned on and this was throwing me off the scent of the real issue.