Charging issue

[ITZ2BIG]

I can't be the only one who has this unique issue?
I'm going to have to buy some extra lottery tickets if I'm that special ��

[gtstorey]

Originally Posted by ITZ2BIG

I can't be the only one who has this unique issue?
I'm going to have to buy some extra lottery tickets if I'm that special ��

I don't remember anything to this extent since I've been on here since 2017. Most usually resolve their problems with a new battery or alternator.

Curious to know if the BCM ever broadcast what status it is in compared to the list i linked in post 2 and if so, how that compares to the requirements for those states.

But at some point, either you got multiple bad replacement parts/battery, or you do have a wiring issue. I would go through and thoroughly inspect all of wiring and make sure all of the grounds were completely clean.

I also think that someone good with a multi-channel oscilloscope could find the problem since they could measure amps, with direction, the pulse width control to the alternator and the voltages.

[ITZ2BIG]

Thanks so much for your suggestions...I've given up on stressing about it...i will drive it around town like normal, enjoy it & on rainy days, look at new areas to try to find the issue & talk to more people, eventually I'm sure I'll figure it out with some help out there?

[gtstorey]

You are using a battery tender and not a full size charger? Some of the full size chargers can cook a battery pretty quickly if left on for an extended period. I don’t really even trust the tenders and move them around my vehicles so they aren’t charging all of the time.

[Mr_Draco]

After they did the update, check and see if the ECU is still having a comm issue. If it is, the port in the ECU is going bad and the ECU will need to be replaced.

You can just google ecu communication failure or ecu communication issue and pretty much every hit will tell you it's a early sign of a ecu going bad.

Remember, the ecu communicates with the entire car. If it's having issues communicating with the charging system, it's only a matter of time it starts having comm issues with the rest of the car and what's going to be next?

[ITZ2BIG]

I've used both full size smart & battery tender chargers but don't leave them on. I have had the battery tested multiple times which is just 2.5 years old & I have put another new battery in with the same results. Yes, since the first auto electric specialist I went to saw the com error & reset it, it hadn't come back on by the time GM checked it.

[ITZ2BIG]

If it is the start of the ECU going bad, it's too bad GM can't run a test on it to confirm as it's a big cost (part & labor) to install. In my talks with GM they tell me they've never heard of a ECM or a BCM going bad & needed to be replaced???? & if it's not a software issue then I'm back to scanning the whole car looking for a wiring issue?

[Mr_Draco]

Wouldn't need to check the whole car. Since you are only have issues with the comm with the charging system, just check the connection at the ecu and check the other end where ever it connects to the charging system.

[gtstorey]

Originally Posted by Mr_Draco

Wouldn't need to check the whole car. Since you are only have issues with the comm with the charging system, just check the connection at the ecu and check the other end where ever it connects to the charging system.

I'll have to check the wiring diagrams tonight. I would have assumed that all communications with any module talking with the ECM would be handled by High-speed LAN, but maybe it has a different comms path for the alternator.

[acutron42]

Here is a brief overview of the system from Alldata. If you guys need more indepth info let me know.

The engine control module (ECM) uses the generator turn ON control circuit to control the load of the generator on the engine. A high side driver in the ECM applies a duty cycled voltage to the voltage regulator. The duty cycle controls the voltage regulator to turn the field circuit ON and OFF. The ECM monitors the state of the generator turn ON control circuit. The ECM should detect low voltage on the generator turn on control circuit when the ignition is ON and the engine is OFF, or when the charging system malfunctions. With the engine running, the ECM should detect high voltage when the duty cycle voltage is commanded high and a low voltage when the duty cycle voltage is commanded low on the generator turn on control circuit.


The engine control module (ECM) uses the generator field duty cycle signal circuit, or F-terminal circuit, to monitor the duty cycle of the generator. The generator field duty cycle signal circuit connects to high side of the field windings in the generator. A pulse width modulated (PWM) high side driver in the voltage regulator turns the field windings on and off. The ECM uses the PWM signal input to determine the generator load on the engine. This allows the ECM to adjust the idle speed to compensate for high electrical loads. The ECM monitors the status of the generator field duty cycle signal circuit. When the ignition is ON and the engine is off, the ECM should detect a duty cycle near 0%. When the engine is running, the duty cycle should be between 5–99%.


Circuit/System Verification
Note: Do not have a battery charger connected during the generator testing.
Ignition ON.
Verify that no G13 Generator , B18 Battery Current Sensor or B110 Battery Sensor Module DTCs are set that would cause a charging system concern.

If DTCs are set
Refer to Diagnostic Trouble Code (DTC) List - Vehicle.


If no DTCs are set

Verify the scan tool Body Control Module Battery Voltage parameter is 12 V or greater.

If less than 12 V
Refer to Battery Inspection/Test.


If 12 V or greater

Engine running, all accessories OFF.
Verify the scan tool Body Control Module Battery Voltage parameter continually increases when controlling the Body Control Module Generator Regulator Setpoint from 40% to 90% with a scan tool. It may take up to 10 s for the battery voltage to stabilize between each setpoint change.

If the battery voltage does not continually increase
Refer to Circuit/System Testing.


If the battery voltage continually increases

All OK.

[ITZ2BIG]

Thanks so much for the feedback & in depth info.

[ABM2SS]

I had a similar issue with my Camaro a few years back. After going through replacing the Battery and Alternator... It turned-out an intermittent short. The engine wire harness chaffed through and a wire was shorting against Right Head. Fixed that issue and the problems went away. Check your harnesses.

[ITZ2BIG]

Thanks for the feedback...I'll check

[SummitWhite11]

Originally Posted by gtstorey

You are using a battery tender and not a full size charger? Some of the full size chargers can cook a battery pretty quickly if left on for an extended period. I don’t really even trust the tenders and move them around my vehicles so they aren’t charging all of the time.

I have been using a DieHard battery tender on my vehicles for almost 30 years. My current Camaro has been hooked up to a DieHard battery tender for 6 years now with no issues. I take her out for a spin once a week or maybe once a month depending on my work schedule. A recent lightning storm a few weeks back fried my 25+ year battery tender. I replaced it with a newer DieHard.