tiesi81

Hey everyone I'm sure this has been on here before but I just want to make sure. I have a 2002 z06 that won't start. I've replaced the ignition lock cylinder, ingnition switch, clutch safety switch, anti theft relay, the battery and the starter. I can get the car to start and run if I jumper the purple and red wires on the anti theft switch but nothing with the key. I don't have an codes that relate to the BCM being bad or the VATS. Does this mean i should replace the BCM? It's the only thing else I've found on the internet that says it could be the problem. Thanks for any help.

dgrant3830

What codes do you have?

tiesi81

The only code I'm getting right now is u1064 which is strange because none of my old codes are showing up. When I turn the key nothing at all happens except maybe a click in the passenger foot well area. If I leave the key in run and jumper the wires on the tdr it starts right up and runs fine. The security light goes out before I try to start it as well.

tiesi81

Well I unplugged the bcm a couple of days ago to check the connections so I'm guessing that might be why the loss of com code. But I don't remember the old codes and they aren't showing up now so I'm not sure how else I can give u that info.

dgrant3830

To diagnose this, you need the BCM plugged in and also, without the BCM, its certainly not going to start. The BCM and PCM communicate to each other, sharing a secret password which is required to match on both modules in order for the programming to allow the car to start.

tiesi81

I did plug it back in.

dgrant3830

Ok, so everything is plugged in, hopefully you've checked all the fuses and the security light is not flashing, yet all that, the TDR is not engaging, therefore not commanding the solenoid to turn on, starting the car? Have you re-pulled the codes? Is your car a manual transmission and if so, please check the clutch safety switch at the clutch pedal. I don't know about the A4's but there's a switch for those as well to insure the car is either in park or neutral.

Bill Curlee

OK,,,,,,,,,,,,,, HANG ON!!!!!

Here is the starting schematic that you need to PROPERLY trouble shoot this issue!!!!



Your going to need to obtain a Digital Volt Meter and take some readings.

The wires that you need to check out are the YELLOW and the YELLOW/BLACK wires on the TDR.

DO YOU have 12 VDC (battery voltage) on the (C2 YELLOW wire) when you have all the conditions met to start the engine????

If you have 12 VDC on the yellow wire when you attempt to start the engine,, you can GROUND the YELLOW/BLACK wire and the engine should crank.

Thats all that the BCM does is allow that YELLOW / BLACK wire to ground to complete the circuit and allow the TDR to energize and make the high current realy contacts SHUT and connect the RED and PURPLE wires.

If you do NOT have the 12 VDC on the yellow wire, check both of the fuses in the ignition circuit (ING2 fuse #50 and CRK fuse #14

BC