Alright so my C5 won't start.. sometimes and I can get it to start with one quick trick. I disconnect the negative battery terminal and reconnect it and it will fire right up. Then after some time (not sure exactly how long) when I get in the car and turn the key on I get my normal ABS and Traction control codes (haven't tackled that yet), but then it will say Reduced engine power and low fuel and it won't start. Not just won't start it won't click, roll over, nothin, it's like there is no battery hooked up. Again disconnecting the negative terminal and reconnecting it gets it to fire right up.

So far I've cleaned the ground connections under the battery and in the front two connectors under the hood (I know there are many more working on getting at all of them). I've got a new battery checked out all good. Alternator seems to be cranking out 14v no problem. I have had to do the LMC5 module bypass to get rid of the Pull key wait 10 seconds code.

I have not yet looked for the Anti theft relay might try and find that tomorrow. I was planning on trying the VATS Bypass but I'm not seeing a Security light on so I'm doubting that will help.

Any suggestions would be greatly appreciated and thank you for even reading this far.

 

I had similar issues for 6 months. If you have another key, try it. Also, squirt some CRC Mass Air Flow Sensor Cleaner in the ignition,. I finally had my go to mechanic replace the switch (it took four to get one that worked). All is well now.

 

The anti theft relay or TDR as it's called is located above the BCM in the passenger footwell area, it has four wires a red, violet and two yellow wires one has a black strip. The BCM provides a ground to the TDR coil when everything is working properly, the TDR is energized and sends power to the starter solenoid which cranks the engine over. Your car has either a intermittent seriel data highway issue or the BCM itself is at fault. When you disconnect and reconnect the negative battery cable you are performing a power reset which allows the car to crank over at least once.

 

I see you're way out there in the Pacific...if you have a code reader see if you can communicate with the PCM...if not maybe a serial data bus issue with what you're seeing...if you have a factory level scan tool you can see if you can communicate with the BCM...if you can communicate with PCM may be a BCM issue if no comm with the BCM ...both must communicate with each other for the car to start...if no scan tool retrieve codes through the DIC and check for any "U" or communication codes...I see you have an "03 Z06....good to put that in your profile with any other information.