I have two C5's I'm working on issues with both of them. So, you'll see two different posts, they are not the same vehicle.

This car was running and driving, but it was throwing some trouble codes.

From the trouble codes, reading on the forum, and checking with a meter I discovered that one of the contacts in the ignition switch was burnt. I removed the ignition switch, sanded the contacts, and re-installed the old switch. The car had power through all the circuits but would not start. I bought a new ignition switch just in case I damaged the switch in cleaning the contacts. That did not fix the issue.

PCM is throwing B2723 H C

The Security light flashes when the door is open. When I put the key in the ignition and turn it on, the Security light is on solid.

I have two original factory key for the car. Both Ohm out at the same value. I have checked the ohm output from the key switch, and it ohms out the same.

I have performed a relearn (3x10 minutes, etc...) with both key multiple times. During the 10 minute wait the security light (which should go out) never does. I have waited as long as 30 minutes, the security light never goes out.

I have installed a brand new battery to ensure the battery wasn't an issue.

The only other codes the car is generating other than B2723 is A/C related (exterior air temp sensor, and an issue with an actuator door)

Any other suggestions?

 

Please be more specific about the car not starting, does the engine crank over, but fails to start, or does it do nothing. The security light should go off after turning the key on, you didn't by chance forget to plug in the small connector for the two small wires from the key pellet contacts of the Ignition switch.

 

Before I removed the switch to fix the contacts the car ran fine.

After removal when you turn the key all the way to the start position, nothing happens.

All the harnesses are plugged in. I have also verified the ohm value at that connector.

The B2723 code indicates a VATS issue. The BCM is not recognizing the key, and the will not allow it to crank.

I have performed the VATS relearn multiple times.

One of the things that should happen during the relearn is the security light should go out on the dash. It does not no matter how long it sits.

 

Have you measured the resistance of the key right at the input to the BCM? You might try disconnecting the negative cable at the battery and reconnecting after a few minutes, and trying starting it, if it cranks it's an indication that your BCM could be at fault, hope this helps.

 

Found the issue….

When I was putting the car back together there is a 2 wire harness (green and gray) that plugs in just fine to the key connector. Right next to the key.

However, the proper harness is the purple and white 2 wire harness.

It had fallen into the back of the dash. I found it, immediately heard the relay click over in the passenger footwell. I hit the key and the car fired right up…

 

HP Tuners will let you turn off VATS.

 

I was thinking it was a connection issue.. i noticed these VATS wires are also in the prime location to be pinched as you reinstall the plastic fascia. I personally bypassed mine with a set of resistors - i need to re wire in a kill switch though.

 

When I think of VATS

 

Yeah, some folks insist on calling it VATS, although there has not been a VATS module on a corvette since the C4.

 

What is it actually called on the C5? It was labeled as VATS in HPTuners when I turned it off lol.

 

It's VATS, which is built into the BCM, consists of the resistor key pellet reader in the Ignition switch which enables the BCM to provide a ground to the TDR. Don't know much about HP tunners but turning VATS off is disabling the input from the BCM to the PCM to allow fuel delivery.

 

Pass-Key, and VTD(vehicle theft deterrent). The operation is similar to VATS...but not the same.
Not sure if HP tuners just turns off the PCM wanting a password from the BCM to enable fuel only or it also includes the Pass-key portion for the TDR.

 

Good to know

 

It must do it in a way to not mess with that input. My car runs and drives with the setting turned off.

 

Need some help with the same issue. I installed the vats bypass module yesterday and the car still did not want to start. Battery voltage measured good, the security light is no longer on when the key is in the on position. Is there any special steps I need to perform after installing the module? Followed some YouTube videos and seemed like they just installed bypass and it worked right away. I have an 03 Z06, thanks.

 

Please be more specific when stating car did not want to start. Does the engine crank over but fail to start, or does it do nothing at all.

 

start your own thread.

 

Did not want to start new thread since this was already posted, but I can if need be.
The car will not crank, everything works but car will not start. I have already performed the lmc5 mod on I take care of that issue so I next installed the Vats bypass module to hopefully take care of the key/ ignition problem I’ve been having.

 

 

It’s crazy to think that there is no fool proof way to eliminate the key ignition problem knowing how many C5 owners have had to deal with it, even YouTube has barely any videos. I’m hoping for some basic go to checks I can perform to figure out the issue, appreciate any help you can provide.