Mk7 Golf (MQB) boot light failure diagnosis

[blueST]

Can anyone help me diagnose and fix this.

Late last year I bought an absolutely mint Mk7 GTI, literally the only fault is the boot light doesn't illuminate. Most irritating att his time of year. I have removed the lamp from the car and powered it from a separate battery so I know the bulb and holder are good. I even checked the resistance of the diode in the holder and it's correct and properly orientated.

My understanding is that on these MQB cars the boot light is controlled by the body control module (BCM) rather than a simple switched and fused 12v feed. There is no separate fuse for the lamp. When I open the boot, the warning illuminates on the dash screen, so I believe this tells me the that the switch in the boot latch and associated wiring is ok.

If I measure the voltage at the plug for the light fitting, with the boot closed it shows 0.5v (maybe that's some sort of continuity check by the BCM?). With the boot open it is 11.8v which seems low to me, but I don't know what the BCM would normally put out.

Any thoughts on where to look next?

[Dr G]

Wire a tester directly to the pins - any 12v lamp.

[catso]

blueST said:

With the boot open it is 11.8v which seems low to me, but I don't know what the BCM would normally put out.

A 12v bulb would illuminate at 11.8v so, something else is not right. Is the bulb the correct wattage?