Mattias Sandgren Posted January 18, 2018 Report Share Posted January 18, 2018 Car : Audi TT quattro 1.8 turbo year 2000 (mfg 1999-09-20) with APX engine. Issue : With the engine running you can turn the ignition key to off position (and remove it from the ignition lock if you want) and the engine and all lights are still running. Pretty sure "brake + clutch drop in gear" is not going to cut it as the go-to solution for the customer. Is this a known issue? The car and engine is completely standard/stock, and with the original ECU this does not happen. Quote Link to comment Share on other sites More sharing options...
ClintBHP Posted January 18, 2018 Report Share Posted January 18, 2018 Sounds like something is wrong on the car's wiring. The Link ECU requires that the Main relay's positive side of the coil is ignition switched, your Audi should be ignition switched, so either its been rewired or the alternator's diode in the sense circuit is missing or shorted. The reason for this is that the Link ECU pin 3??? is connected directly to ground so with the ECU present the main relay will be switched on, however the OE ECU will not. Quote Link to comment Share on other sites More sharing options...
Mattias Sandgren Posted January 21, 2018 Author Report Share Posted January 21, 2018 Oh, sounds a bit like the issue I had wiring a Link Fury to an Audi RS4 -99, where the fuel pump relay was turned on as the outputs all short to ground with the ECU off. I had to install a separate relay, powered through the ignition, in series with the ground side of the solenoid of the fuel pump relay. The fuel pump relay solenoid positive side either had current leaking through the ignition lock or it was always powered. I'll have to check if there is a "hold" function of sorts.. Quote Link to comment Share on other sites More sharing options...
Mattias Sandgren Posted January 31, 2018 Author Report Share Posted January 31, 2018 Turning off the engine now works, but did a quick solution. Out of all the "key on" signals in the car only one was found to really turn off at the key, so wiring in a relay was the best option. There is probably some kind of "hold relay" in the car that is controlled by the stock ECU and chassis electric units, might be a signal through CAN-BUS. Also this particular model car with APX engine apparently is the only one to have this particular Bosch ME 7.5 ECU, oh well. Quote Link to comment Share on other sites More sharing options...
ClintBHP Posted January 31, 2018 Report Share Posted January 31, 2018 Glad you got that traced down Quote Link to comment Share on other sites More sharing options...
Cam Monteith Posted December 8, 2020 Report Share Posted December 8, 2020 On 1/31/2018 at 1:07 PM, Mattias Sandgren said: Turning off the engine now works, but did a quick solution. Out of all the "key on" signals in the car only one was found to really turn off at the key, so wiring in a relay was the best option. There is probably some kind of "hold relay" in the car that is controlled by the stock ECU and chassis electric units, might be a signal through CAN-BUS. Also this particular model car with APX engine apparently is the only one to have this particular Bosch ME 7.5 ECU, oh well. Im having the same problem, are you able to remember what wire you ended up using? Seems like i have tried every wire in the car but either they lose 12 volts when the car is cranking or they dont turn off when the key is off. Quote Link to comment Share on other sites More sharing options...
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