coyn11

Ok, I put out a post about a month and a half ago about my car not cranking. I am determined to get it to work. I need a systematic way to diagnose the issue.

This is what i know:
It will crank once every 75ish tries
It will crank and start every time i remote start it via aftermarket remote start system
sometimes the problem goes away for a few days

I also have the service manuals and a Tech ii emulator (tech2win)

https://www.youtube.com/watch?v=M8E8mhQeia0&feature=youtu.be


What should i try first?

Slowbalt2000

iTrader: (1)

Sounds like maybe an issue with your ignition cylinder. Have you ever had the recalls completed?

coyn11

Yes back when the recall happened I got it done.

Kolt

I would remove the aftermarket remote start/alarm kit first, I have seen those things cause theft issues and keeping the vehicle from starting.

coyn11

I have unplugged everything that the aftermarket remote start is plugged into and reconnected the one ignition wire that is spliced for the install. this reconnects the stock wiring like stock. I am avoiding completely disconnecting the wires because this is my DD and its currently the only reliable way i have to start the car. I also just went and took video of the problem and the ignition test from tech2win

https://www.youtube.com/watch?v=YXbB...ature=youtu.be

Kolt

Go to vehicle control system, build the options and there should be a class 2 data option. Pull it up and see if any modules show a class 2 failure or code. Ones with a failure or code will say yes and good modules will say no. List what ones say yes or grab a screenshot.

Edit: Idk why but the first part of my reply got deleted, im going to bring my mdi2 home and run through tech2win on my ls and ss. Your accessory signal doesn't look right. The ecm is getting crank request from the ign cyl which is good but as you can see it is not commanding the starter relay on. Also did you happen to look at the vtd data line in ecm data and see what it showed during crank request?

coyn11

I found the midi.2 option here is the modules test:













Also here are the DTC's:
















I redid the ignition test with midi.2 interface and tried to find the vtc data line in "ecm data" and did not find it. What should i be looking for? Also here is the ignition test:


Also, thanks for bearing with me. i dont use the tech ii very often, only use it when i need it, i get lost in all the menu's. haha

Kolt

I ended up forgetting to bring my cable for my mdi2 home, im gonna try to swing by work tomorrow and grab it. The codes set in the theft deterrent module can cause your concern but they are history which would mean it should start. Clear all the codes and when it doesn't start leave the key on and pull the codes again on that screen. See if any of those codes you had set in the theft deterrent module reset as current. Also your getting some low voltage codes and a checksum code. Your battery voltage going below 10.5 can cause those. Need to have a battery recharged and keep a tender on it while you have the key on running through tech2win. Its all good its actually really nice to see someone have the right tools, makes it easier for me to help you diag it. I apologize I forgot my cable, when I get it hooked up tomorrow I will run through and find where the data list I need you to look at is. Hard to remember without having it in front of me lol

coyn11

Dude, thanks so much for helping out. I'll clear the codes and get that on a charger. I didn't expect my voltage to drop that much in 30 minutes. 😅

Kolt

Busy weekend but I finally got a chance to go out and get a couple vids of what I want you to look at to compare. Lemme know whats not matching up, I know your accessory voltage looked like it wasn't matching up like it should have but double check.
ecm electrical/theft data
https://www.youtube.com/watch?v=DeCv...ature=youtu.be
Theft module data
https://www.youtube.com/watch?v=-Swu...ature=youtu.be

coyn11

Ok, I found the Electrical/Theft Data display. I added some of the lines in that i could, sorry they are mixed up. I took photos of each key state: acc, run, start I could not find some of the values that you have listed in your list. I had 11 options in Electrical/Theft Data Display, you have 29? Im going to look into the acc signal. in this display.

Here are the pictures of each menu...
https://drive.google.com/file/d/1MX2...ew?usp=sharing
The Picture titles indicate menu, context, and key state


TDM Data Display seems to correspond with your values
Learn Key Data seems to correspond with your values
Powertrain Status Match except "PCM Fuel Continue"

A note about fuel, in the past couple weeks i found a fuel leak I will fix that this weekend. when i noticed this fuel status didn't match yours i went to try and start the vehicle while staring at that screen. i was eventually able to start it with the key and the "PCM Fuel Continue" Status didn't change.

Im going to toy around with my techii and see if i can get more options to show up in the theft menu. in the meantime i will look into the fuel leak and the ACC signal. I will go over the wiring for my aftermarket remote start and see if i cant track down the ACC issue.

Kolt

You might not have all the data I do bc mine are 08's. Everything on the theft side looks good but as I noticed before your missing your acc signal so we need to start there. Whats your vin and I can get you some wire diagrams and show you where you need to start checking.

coyn11

Vin: 1G1AP14P067788929

Are there resources outside of the service manual's? Are all electrical diagrams available in the service manuals?

Kolt

It depends on what service manuals you have. I work at a gm dealer so I have access to gm service information which includes just about anything anyone may need. When I get a min ill run through and get diagrams and connector views to show where I would start checking first.

Kolt

Sorry I got caught up yesterday and ended up forgetting to post. I would start by using a incandescent test lamp to see if you have power on terminal 4 on the ign switch when the key is in acc. Double check after it lights a test lamp that you have full battery voltage. If you don't then check for power at terminal 2 on the switch, it should be there at all times. If you don't have power there then check fuse 8 in the bcm. If you have power at terminal 4 on the switch then go into bcm data and look for the accessory power data line to see if the bcm is getting the signal. If your not then check at terminal c8 on bcm connector 4 for power. If you have power there but the bcm doesn't show it then your looking at a bcm issue. If your bcm is getting signal then you need to check for power coming out of the bcm at terminal b5 on bcm connector c3. The power from terminal c8 connector c4 is supposed to pass straight through the bcm. If you don't have power there then you know you have a open inside the bcm. If you have power there then you will move on to ecm connector 1 terminal 18 and check for power there. If your getting power there then your looking at a potentially bad ecm.
Here is all the diagrams and connector end views you will need. If you have any questions about anything just ask, I know that was a lot to take in.
BCM connector 3 is red
BCM connector 4 is light gray
ECM connector 1 is blue inside
Ignition switch wire diagram.pdf
Ecm power and ground wire diagram.pdf
BCM c4 end view.pdf
Ignition switch connector view.pdf
BCM c3 end view.pdf
ECM c1 end view.pdf