Hi guys, Little steer here please. For a while now I haven't been able to connect to my engine ecu, so today I have checked the k-line is all connected. If I'm tracing the right cable, the engine ecu k-line comes in through th bulkhead on the drivers side and goes to the immobiliser box beside the instrument cluster. From the immobiliser box it comes out and connects to the junction box on top of the fuse box, from there it links to the obd2 port as well as the abs module exiting the bulkhead on the passenger side. Now all these wires are in place. But I can only connect to the abs module. I've read a few things on the net but most of the time the engines don't start so my issue is slightly different as my car starts and runs fine, I just want to chat to the engine ecu... Lonely life! I've checked my fuse box and I don't have relay 30 which says its for engine management. Should my car have this relay? Also can I bypass the immobiliser k-line to check the signal is getting through? Mk3 vr6 1996 Thanks
K-line from ECU = pin 43 That wire goes to the immo and daisy chains to a current track on TV14a. That current track is shared with other modules, such as, klima etc. TV14a also feeds out to the DLC on pin 7.
Thanks. So if all the k-line wires are connected why wouldn't I be able to communicate with the engine ecu or immobiliser ecu? Does my car need relay 30 as its never had it?
Not the first time I experienced this problem ton be fair. Had it on a Mk3 16v also. ECU was the problem in the end. I have an ECU that has been de immo from my old dragon green car. If you are close enough it can be swapped to see if you can communicate with the car.
Thanks Eddie. Where about as are you? Could it not be the immobiliser box not relaying the signal? As I said before everything works so I'm thinking more a comms problem?
it could well be the immobiliser box, i have seen a couple fail in exactly this way. on one of them the car would even start and run just fine as the box could talk to the ecu, but something inside had failed meaning it would no longer pass comms out to the diagnostics. simple test, unplug the immob box and loop a thin wire between the grey/white and grey wires on the plug, if you can then talk to the ecu you know your immob box is stuffed
Bypassed the immobiliser today and the engine ecu talks to vagcom fine so obviously the immobiliser isn't relaying the engine signal to the obd port. So I have split the engine Kline to go to the immobiliser and the obd port at the same time. And all works fine.
