Gearbox Changes Down When Turning Lights On

[Derek The Hare]

Car behaves normally when in daylight without lights on... Turn on lights and the reversing light indicator comes on , on the dash and the car changes down a gear! The reversing lights don't work... Is this an earth problem... any clues ... anybody..?

[ROYT]

First thing to check is for any broken wires in the left side boot hinge.

This sounds like it might be this known fault...

[terry moore]

Car behaves normally when in daylight without lights on... Turn on lights and the reversing light indicator comes on , on the dash and the car changes down a gear! The reversing lights don't work... Is this an earth problem... any clues ... anybody..?

Hi, check your reverse light bulb holder,and bulbs.U might be getting a live feed from the tail lights to your reverse lights,which in turn brings your reverse sign on.To test this just remove the rear tail light plugs one by one ,check which one it is :winky: Cheers Terry

[Derek The Hare]

Absolutely spot on to both RoyT and Terry... The thicker White with Black tracer cable in the bundle looked like it that been cut cleanly but was invisible because it is buried under sticky sleeving in the Boot hinge AND the 12V was feeding back to illuminate the Reverse light. I guess this was confusing the ECU as maybe it selects or locks the gearbox in a lower gear or driving profile for reverse...

Interesting that the Lexus main dealer wanted to strip the gearbox for £2k.... I dont think so...

Anyway thank you both VERY MUCH....

Regards Derek