2009 no crank

[Black_Blade]

Driver said car was working fine, when he put car in gear from park, car stalled and then wouldn't crank.

• no DTCs
• verified that starter turns engine over by jumping it from the starter relay
• pulled out ecm and verified that the transmission range switch is functioning
• ignition switch checks out

For some reason, the starter relay is not getting its 12 volt signal from the ECM to energize the relay, even though the park/neutral signal is giving the green light (goes to low signal)
Been at this all day and still have a car dead in the water..be glad for any suggestions.

[autojoe]

see if there is voltage on white wire from ignition switch to bcm during crank......should be able to locate wire at base of column.should be battery voltage.

When the ignition switch is placed in the Start position, a discrete signal is supplied to the body control module (BCM) notifying it that the ignition is in the Start position. The BCM then sends a message to the engine control module (ECM) notifying it that CRANK has been requested. The ECM verifies that the transmission is in Park or Neutral. If it is, the ECM then supplies 12 volts to the control circuit of the starter relay. When this occurs, battery positive voltage is supplied through the switch side of the starter relay to the S terminal of the starter solenoid.

[Black_Blade]

Yes, I had read that passage as well and was wondering about how to check for this 'discreet' signal. Pretty sure I had checked that white wire but will do check again and post back.

[Black_Blade]

White wire has 4 volts when switch in OFF, turn to CRANK and it drops to 3 V

[autojoe]

i said above 12 volt but i think it is a 5 volt.Do you have any b codes?bcm fuse okay?Do you have a scan tool? should read crank when turned to start position.I am not too familiar with this system.

[Black_Blade]

We use the auto enginuity pc based scanner, which works really well. We weren't able to get communication with the transmission module for whatever reason, so don't know if there were any tranny codes. We were able to talk to a tech from local dealership and he had us check the pink wire at ignition switch for 12 V at run and crank, which it had. Then check that pink wire at its input to BCM and that was ok. Then check the output of ignition relay control from BCM to fuse box and it had that, but had no power to several sections of fuse box..was able to find the yellow wire in the loom just before fuse box and still was 12 V...so seems the PCB of the fuse box has an issue. We have ordered a new fuse box that will be in tomorrow morning.

[Tech II]

I agree.....look in your owner's manual.......does it have Passkey III or PassLock?

I don't know if your scan tool is capable of reading "B" codes......if a B2958 or B2960 is set, that is your problem....

If you have PassKey III, when you turn the ignition to on(don't crank), the SECURITY/THEFT light will come on for 3 seconds and go out....if it stays on, you have a PassKey problem......

If you have PassLock, the only way you know if you have a PassLock problem is, if it flashes after you release the key from the crank position(unfortunately, sometimes it doesn't flash and there is still a problem)....this light does not go out after 3 seconds, like in the PassKey test.....with PassLock, it only goes out AFTER the car has started.....

[Black_Blade]

Had a tech from local dealership give us some help over the phone. He had me check:

• pink wire at ignition for 12 V- it did
• check that same wire at the input pin of the BCM- it did
• output pin of BCM to fuse box (starter relay)-it did
• also checked for this 12 V signal just outside the fuse box - it did

We found some spots on fuse box that had no power that should have with key on engine off, but this system of checks and following the start signal from the BCM to the fuse box allowed us to condemn the fuse box..must be some fault on the circuit board. We ordered a new fuse box, installed it and problem solved!

The biggest problem I had (still learning how to follow wiring diagrams and diagnose things of this nature) was I had different diagrams showing me wire routing to different things. On one diagram, I was seeing that the ECM was routing a signal to the starter relay, so I had it dug out and was checking for various signals with key in various positions (this was how I determined that the transmission neutral switch was functioning properly). In another it showed, what turned out to be the correct thing to be using, the yellow wire running from BCM to starter relay.

Thanks for the input guys, and I hope this information is a help to others in a similar spot!