Strange Immobiliser / Battery Drain Fault

[grendal10]

im having a few problems with my c5 2.0 hdi 2002, first problem was the battery was draining completely if not used for a day to 2 days, which turned out to be the rear interior light, if its turned off the bulb still has a small glow . i then found out if the bulb is removed or the interior light is unplugged the car wont start and comes up with immobiliser fault, if the bulb is plugged back in and ignition turned off and back on the fault goes and the car starts fine. just wondered if anybody had any ideas? 

[paul.h]

Welcome to the forum.

 

An odd thing like this could be an earth wire or earthing point fault

[MikeLane]

Sounds like a short circuit to me - maybe in the fusebox, as if the immobilser circuit is being mis-routed through this lamp (or through the cabling/fuse where the circuitry originates.) Might show up on a Lexia? Have you checked for voltage in the lampholder when ignition is off and bulb removed?

[coastline taxis]

Have you got led lights in the car

[grendal10]

ive checked with lexia cable and no faults were found, its got standard bulbs no leds, ill check for voltage when the ignition is off and see what i find