[Techn9cian805]

I'm on my second starter now. First one died last year, a month after warranty... i replaced it, but it still has slow cranks, and i notice them happening when driving for long periods, it seems to be starter heat soak, but i'm not sure.. regardless, i got a starter heat shield wrap i still need to install and see if that helps.

[Ailurus2SS]

Originally Posted by Techn9cian805

I'm on my second starter now. First one died last year, a month after warranty... i replaced it, but it still has slow cranks, and i notice them happening when driving for long periods, it seems to be starter heat soak, but i'm not sure.. regardless, i got a starter heat shield wrap i still need to install and see if that helps.

After I replaced my first starter, I never noticed the heat soak come back or slow crank yet

[Ailurus2SS]

Also as an update the new alternator was put in today and nothing changed. He tried charging my battery for 8 hours and it wouldnt hold a charge. He swapped in a battery he had in the shop and the battery held a charge but would turn over still.

The car was still cranking like there was no gas and the 3 codes appeared again U0109 (fuel pump lost connection), u0121 (brake lost connection), and u0140 (bcm lost connection.

He said he's gonna have someone come to the shop to reflash the bcm to make sure it didn't get corrupted or something from losing power when the batteries died

[Techn9cian805]

Originally Posted by Ailurus2SS

After I replaced my first starter, I never noticed the heat soak come back or slow crank yet

Yet is the key word. I replaced it in August of last year, and the slow cranks started again about around January when i began to start hitting canyon runs again. Drive it hard a while and see to be sure its not the same heat issue, i often take my car thru canyon roads, so i'll be balls to the walls for like 5-10 minutes at a time, and thats when i would notice the engine heat being high when the hood would get popped open, and then the slow cranks would begin again.

On really hot summer days i'm also having slow cranks after a few hours or minutes of driving and repeatedly turning off and on, so idk, i feel its a heat soak issue for me, maybe yours might be different

[Ailurus2SS]

Originally Posted by Techn9cian805

Yet is the key word. I replaced it in August of last year, and the slow cranks started again about around January when i began to start hitting canyon runs again. Drive it hard a while and see to be sure its not the same heat issue, i often take my car thru canyon roads, so i'll be balls to the walls for like 5-10 minutes at a time, and thats when i would notice the engine heat being high when the hood would get popped open, and then the slow cranks would begin again.

I always drive my car hard. Never turn down a race at a light haha but I plan on getting ceramic coated headers soon to really bring the temps down in my hood as a preventative

[Ailurus2SS]

So my mechanic believes the bcm might have lost memory or something from losing power from the alternator and battery. He's gonna have someone from chevy come scan it. Well see how this goes...

[ctrlz]

Originally Posted by Ailurus2SS

So my mechanic believes the bcm might have lost memory or something...

I'll go for the or something. If your alternator was pumping out AC it could damage a module such as bcm. The voltage regulator can't regulate AC like DC.

[Ailurus2SS]

So he fixed a ground in my trunk and it was able to get me home but the next morning I was half way to work when engine lost power and when I rolled to a stop, it shut off. Same codes and issue again. Going to the dealership this time

[Ailurus2SS]

Originally Posted by ctrlz

I'll go for the or something. If your alternator was pumping out AC it could damage a module such as bcm. The voltage regulator can't regulate AC like DC.

So could the bcm be having intermittent problems from that because the car worked, for a day.

[ctrlz]

Originally Posted by Ailurus2SS

So could the bcm be having intermittent problems from that because the car worked, for a day.

The last time I had this problem was in a non-computerized car. I fried two voltage regulators before I realized there was a shorted diode in the alternator. I knew my voltage regulator was gone when the brightness of the dash lights would change with engine rpms! I don't know if you would get any warning signs in a modern car. Even our built-in voltmeter in the Camaro is a computer display.
From what I have read, computer modules are less tolerant of AC. Low voltage AC can result in "noise" which just confuses things. Higher voltage can damage modules.

[CoolbreezeNJ]

I'm thinking your mechanic is a hack. Completely charge battery. Crank engine and see if it doesn't go below 9.6 volts and that should be that. Check alt while running and see if is is putting out 13+ volts.

Did you go thru the entire fuse block and see if there is anything applicable that might have blown???

Go to connections for HP fuel pump and remove and then re-plug them in. With key on can you see 12V at that fuel pump?? Is the HP fuel pump even electrical or is it mechanical as in a diesel. Probably not possible for LP pump which I'm guessing is in tank .

Check connections on alternator and remove and replace them.

Start car ,go thru all the accessories and turn them on one by one and see if vehicle is maintaining a charging voltage. While doing this bring rpm up maybe to 2000 rpm and see if it is still holding voltage. I believe that these cars have a "smart regulator" from what I might have read where it is looking for the BCM to measure voltage and then re-signal the regulator in the alternator. If you have a 2nd voltmeter and can get to the fuel pump connection monitor that voltage while your doing the rest of the stuff.

I'm almost 60 yrs old. I put myself thru college working on cars and have fixed them and nearly everything in my house since. What I have learned is to be patient and collect data as I would say that "throwing parts at stuff" has only worked 30% of the time. I would not be asking anybody to check my BCM until I went thru the scenario above. I would assume the BCM is non-volatile memory. It either works or it doesn't but it would be the last thing I'm looking for and at that if the charging system relies on a BCM signal then no doubt you could see that signal at the alternator connection.

If I have time later today I'll go thru this scenario on my own car minus HP Fuel pump voltage and report back.

[ember1205]

Originally Posted by CoolbreezeNJ

I'm thinking your mechanic is a hack. Completely charge battery. Crank engine and see if it doesn't go below 9.6 volts and that should be that. Check alt while running and see if is is putting out 13+ volts.

Go to connections for HP fuel pump and remove and then re-plug them in. Probably not possible for LP pump .

Check connections on alternator and remove and replace them.

Start car ,go thru all the accessories and turn them on one by one and see if vehicle is maintaining a charging voltage. While doing this bring rpm up maybe to 2000 rpm and see if it is still holding voltage. I believe that these cars have a "smart regulator" from what I might have read where it is looking for the BCM to measure voltage and then re-signal the regulator in the alternator. If you have a 2nd voltmeter and can get to the fuel pump connection monitor that voltage while your doing the rest of the stuff.

I'm almost 60 yrs old. I put myself thru college working on cars and have fixed them and nearly everything in my house since. What I have learned is to be patient and collect data as I would say that "throwing parts at stuff" has only worked 30% of the time.

In general, there are very few "mechanics" left in this world. Everyone is a "technician" now because of all of the electronics in cars today. While your approach would work great on cars that are at least 20 years old, there a lot of tech in ones like the Gen6 Camaro that you need a lot of special equipment to trace, diagnose, and test.

One example is that the charging system in the car doesn't just need to output 13+ volts... It has to also output a minimum amperage AND needs to be verified to switch into a "maintenance mode" when the battery reaches full charge because AGM batteries are extremely sensitive to overcharging.

[ctrlz]

Originally Posted by Ailurus2SS

My mechanic said the alternator was bad...

Looking back on this thread, I'm not sure how your mechanic determined alternator was bad.
As others have pointed out there are systems that can prevent the alternator from doing its job.
At least at the dealer you will end up with some kind of printout that shows the troubleshooting chain and what they found.

[CoolbreezeNJ]

Originally Posted by ember1205

In general, there are very few "mechanics" left in this world. Everyone is a "technician" now because of all of the electronics in cars today. While your approach would work great on cars that are at least 20 years old, there a lot of tech in ones like the Gen6 Camaro that you need a lot of special equipment to trace, diagnose, and test.


One example is that the charging system in the car doesn't just need to output 13+ volts... It has to also output a minimum amperage AND needs to be verified to switch into a "maintenance mode" when the battery reaches full charge because AGM batteries are extremely sensitive to overcharging.

Tech or mechanic doesn't matter your paid to fix the car so fix it and yes things are more complicated which means you have to be more rigorous in your approach. High tech isn't an excuse!!

Doesn't matter maintenance mode or other wise. The modules are there to collect data from a bunch of sensors and via the logic that is programmed into it, output a signal to provide a course of action.

That course of action in this place either seems to be a loss of voltage or a lack of fuel both of which keep the engine running. You also have a code that is linked to the fuel system that is telling you loss of voltage. Could that "logic engine" , (BCM) be broken? Could be but what about all the circuits that provide it with those inputs ?? Does the logic even work without the correct voltage --- probably not.

Few like working with electricity for the most part because you can't see it and feel it. It was the same 40 years ago!!! Real easy to turn wrenches and replace parts. Actually takes some talent and effort to trouble shoot things.

Put a known good battery in it. Clear all the codes. If the engine cranks but doesn't start it is either not getting spark or fuel. Spark is easy to check. Do the codes come back?? If it wasn't getting any fuel I suspect it would but I bet it gets fuel, starts and then dies later because the charging system isn't working correctly. That condition was also reported.