Bentley Flying Spur rear courtesy lamp not working

[TungNguyen]

My BFS 2007 got the issue with the rear courtesy lamp:

When I push the switch to turn on rear interior lamps, only two lamps under the front seats turn on. The rear courtesy lamp (map light) won't turn on.

If I turn on the auto door open switch, when the rear door is open, only 2 lamps under the front seats turn on, the courtesy lamp is still off.

So either way can't turn on the courtesy lamp. I checked all bulbs and they are fine.

Has anyone got this issue and how to fix this?

Many thanks!

[TungNguyen]

Hi Zulu, thanks for your feedback.

Zulu 10 said:

Firstly, I presume that you're referring to the central rear interior lamp (not the individual map reading lights), and I wonder: has the interior lighting ever worked correctly during your tenure?

You are right, it's the main rear map light, the 2 reading lights are working fine. To be honest, most of the time I drive alone so I don't really know when the rear map light stopped working

Zulu 10 said:

All the rear lighting is controlled by the Roof Control Module which is located in the front roof console.

On my car, the rear RCM has its own board with switches. I open the RCM and checked, everthing seems fine with no sign of broken wire or damaged mainboard. However, the voltage I measured at the map light is 0. Its negative wire is ok, but positive wire has no voltage / signal.

Zulu 10 said:

The next obvious question is whether you've fitted LED bulbs, because these can confuse the Roof Control Module - I know because I'm going through the changeover myself at present, and am figuring out where resistors need to be added.

You are right again, I've changed all interior lamps to LED and all work just fine except the rear map light. The front map light works great, just plug the LED in and it works right away.

Here is a short video clip showing the issue: https://www.youtube.com/watch?v=0YSQg_U3fII

Zulu 10 said:

If you get a copy of IETIS - the technical information CD - of which copies exist on line, it contains circuit diagrams for all the lighting functions. That may help your diagnosis.

Finally, it occurs to me that the Roof Control Module is probably common to the GT, and IIRC not all cars were fitted with rear roof light panels (GTCs?) so I wonder whether your car's RCM has had a moment of confusion and thinks it is fitted to a GTC?

A battery reset might cure this, but you'll need ODIS or similar diagnostics which can exercise each lighting function, and check coding, to pursue this avenue further.

Let's me try to find the IETIS CD and see if I can trace the issue. Battery reset means that unplugging the negative plug right?

Edited by TungNguyen on Friday 29th May 09:35