Ignition Problems

[zzzeds]

Hi has anyone had the following, when switching on the ignition the engine management light does not come on and hence the engine wont start! I have to wait anything from 10 seconds to 10 mins for the light to come on, the engine then starts and is fine, this fault is intermittent. The car has been to the main dealer twice but has never occured there! a master technician had the car for two days with no joy and Audi can not shed any light on it and diagnostics, the fault is still there an dwas wondering if anyone can shed anylight on it.. The car is a A4 Avant 1.9 TDI on a 53 plate..

[a8 tech]

There will be a communication interuption between the dash(immobilizer is part of)and the engine control unit.The engine control unit has to be enabled from the dash to authorise start,even though the engine is cranking.This may require a fine eye cast over the electrical terminals and possible dash/ecu replacement.They need to recreate the fault and check that the dash has communication with the engine control unit for the start signal.Try looking inside the engine control unit e box housing.The housing is located under the bonnet next to the wiper motor.Water can enter the e box and corrosion of the connections can occur.The engine control unit sits above the water ingress so is rarely affected but beneath the ecu sits the main multiplugs for the engine bay and thet can become corroded.Just some thoughts to consider.

[zzzeds]

Thats great thanks a lot, if nothing else I will print out and hand it to them as they had no clue. I will also try and check myself. Thanks agaiin.