Onstar notification

JP33 · March 17, 2022

I have had this truck since September and continue to get these OnStar poorly descriptive alert(see below). And the dealer can’t seem to figure it out. Anyone else getting these alerts or do I need to pursue the lemon law??

thanks in advance

JP

An issue with the Engine and Transmission System in your 2021 Chevrolet Silverado has been detected. Please service your vehicle within 1 day.

Please disregard this message if your vehicle is already in for service. Inaccurate notifications can be generated during service.

Please see your dealer for service.

Edited March 17, 2022 by JP33

WeGone · March 17, 2022

First thing I did was turn off OnStar, If your truck is having an issue you should get a message on the dash.

JimCost2014 · March 17, 2022

Lemon law, with no issues with the truck? That will be a tough one to win. More like slim to none, and slim has already left town.

JP33 · March 17, 2022

53 minutes ago, WeGone said:

First thing I did was turn off OnStar, If your truck is having an issue you should get a message on the dash.

The only thing I get is the check engine light goes on. Nothing else first I was told it’s a chafed wire but they couldn’t find it, now they tell me it’s the fuel lines both hi pressure and return which they ordered but are on back order. Can’t wait to see what’s next

JP33 · March 17, 2022

38 minutes ago, JimCost2014 said:

Lemon law, with no issues with the truck? That will be a tough one to win. More like slim to none, and slim has already left town.

Haha funny guy!! Yea yea I know. But ridiculous they don’t know what it is

JimCost2014 · March 17, 2022

5 minutes ago, JP33 said:

Haha funny guy!! Yea yea I know. But ridiculous they don’t know what it is

Personally, I would take it to another dealer. Your truck is not married to the lot you bought it from.

It will be harder now since they have started warranty work, but it is still possible to find someone who will inherit their work.

Would also suggest opening a claim with GM about what is going on, then if you do eventually go the LL route, you have everything documented.

Edited March 17, 2022 by JimCost2014

newdude · March 17, 2022

3 hours ago, JP33 said:

I have had this truck since September and continue to get these OnStar poorly descriptive alert(see below). And the dealer can’t seem to figure it out. Anyone else getting these alerts or do I need to pursue the lemon law??

thanks in advance

JP

An issue with the Engine and Transmission System in your 2021 Chevrolet Silverado has been detected. Please service your vehicle within 1 day.

Please disregard this message if your vehicle is already in for service. Inaccurate notifications can be generated during service.

Please see your dealer for service.

Lemon law? For an OnStar alert? Good lord...

If there are no codes in the truck, current or history, in ANY module, just drive it and ignore the warnings.

JP33 · March 17, 2022

Agreed but once the idiot light comes on a lot of services don’t work like remote start etc so it’s a PITA

newdude · March 17, 2022

1 minute ago, JP33 said:

Agreed but once the idiot light comes on a lot of services don’t work like remote start etc so it’s a PITA

So the check engine light is coming on? There should be codes then.

It's Tim · March 17, 2022

14 minutes ago, newdude said:

So the check engine light is coming on? There should be codes then.

Stated it was P2635 in this thread:

newdude · March 17, 2022

14 minutes ago, It's Tim said:

Stated it was P2635 in this thread:

31 minutes ago, JP33 said:

Agreed but once the idiot light comes on a lot of services don’t work like remote start etc so it’s a PITA

If he still has that code and the dealer didn't follow the diag or the PI, then he needs to take it in and have them diag and follow the DTC and the PI.

#PIP5788A: DTC P2635 Set - (Apr 19, 2021)

Subject: DTC P2635 Set

Involved Region or Country

North America

Condition

Some customers may comment that the SES lamp is illuminated or was Illuminated and turned off, with no drivability concerns. During inspection Technician may notice DTC P2635.

Cause

Unknown at this time

Correction

If you encounter a vehicle with the above DTC, follow the applicable diagnostic flow chart in service information for further diagnosis and repair.

If the diagnostic does not isolate the concern, replace fuel feed pipe (fuel line between the high-pressure fuel pump and chassis line), clear the codes, and return it to the customer.

If the truck has already had the fuel jumper replaced, do not replace again. Follow diagnostic flow chart to ensure a different issue has not developed.

If it does not isolate the concern, clear codes only and return to the custom.

Engineering knows about the concern and is working on a more permanent service procedure.

This PI will be updated as information is gathered.

DTC P2635

Diagnostic Instructions

Perform the Diagnostic System Check prior to using this diagnostic procedure: Diagnostic System Check - Vehicle

Review the description of Strategy Based Diagnosis: Strategy Based Diagnosis

An overview of each diagnostic category can be found here: Diagnostic Procedure Instructions

DTC Descriptor

DTC P2635

Fuel Pump Flow Performance

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Control Circuit Shorted to Control Circuit

Control — Terminal 1 @ A6C Fuel Pump and Level Sensor Assembly - Primary

P102A

P1029

P102B

P102C, P2635

Control — Terminal 2 @ A6C Fuel Pump and Level Sensor Assembly - Primary

P102A

P1029

P102B

P102C, P2635

Control — Terminal 3 @ A6C Fuel Pump and Level Sensor Assembly - Primary

P102A

P1029

P102B

P102C, P2635

Circuit/System Description

For an overview of the component/system, refer to: Fuel System Description

Circuit

Description

Control

The output circuit varies between ground and 12 V.

Component

Description

G12 Fuel Pump

The component has a 3-phase motor. The control module converts the DC voltage from the battery to 3-phase AC to power the motor.

K111 Fuel Pump Driver Control Module

The control module K111 supplies the fuel pump with a PWM signal in order to achieve the desired fuel line pressure.

When the ignition is turned On, the ECM sends a 12 V signal to the control module K111 to enable the fuel pump. If the engine is not started, the control module K111 turns the fuel pump Off after 6 s.

Conditions for Running the DTC

DTC P018B, P018C, P018D, P0641, P064A, P0606, P1029, P102A, P102B, P102C, P1255, P129F, P12A6 = Not set

Fuel Pump Command = On

Ignition Voltage — 11 to 32 V

Engine Run Time — Greater than 30 s

Fuel Level Sensor — Greater than 10%

Frequency the DTC runs = Continuously — After the running conditions are met — For greater than 1 s

Conditions for Setting the DTC

The difference between the following parameters is greater than a predefined value:

Desired Fuel Pressure

Fuel Pressure Sensor

Actions Taken When the DTC Sets

DTCs listed in the DTC Descriptor Category = Type B DTC

Conditions for Clearing the DTC

DTCs listed in the DTC Descriptor Category = Type B DTC

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Master Electrical Component List

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections

Wiring Repairs

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References

Circuit/System Verification

Note: Do NOT replace the control module if DTC P2635 is set.

Ignition » On / Vehicle » In Service Mode

Verify DTC U0074, U18A2 is not set as a history DTC.If DTC U0074, U18A2 is set

Refer to: Diagnostic Trouble Code (DTC) List - Vehicle

If DTC U0074, U18A2 is not set

Verify DTC P018B, P018C, P018D, P0231, P0232, P023F is not set.If DTC P018B, P018C, P018D, P1029, P102A, P102B, P102C is set

Refer to: Diagnostic Trouble Code (DTC) List - Vehicle

If DTC P018B, P018C, P018D, P1029, P102A, P102B, P102C is not set

Perform the scan tool control function: Fuel Pressure » Increase — 300 kPa (43.5 PSI)

Verify the following parameters are within 45 kPa (6.5 PSI) of each other:

Desired Fuel Pressure

Fuel Pressure Sensor

If not within 45 kPa (6.5 PSI) of each other

Refer to: Fuel System Diagnosis

If within 45 kPa (6.5 PSI) of each other

Perform the scan tool control function: Fuel Rail Pressure » Increase — 400 kPa (58 PSI)

Verify the following parameters are within 60 kPa (8.7 PSI) of each other:

Desired Fuel Pressure

Fuel Pressure Sensor

If not within 60 kPa (8.7 PSI) of each other

Refer to: Fuel System Diagnosis

If within 60 kPa (8.7 PSI) of each other

Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

Verify the DTC does not set.If the DTC sets

Refer to: Fuel System Diagnosis

If the DTC does not set

All OK.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair: Diagnostic Repair Verification

WeGone · March 17, 2022

It would look like you need to find a dealer who knows how to work on your truck and the issues.

Bassintodd · May 5, 2022

On 3/17/2022 at 12:11 PM, JP33 said:

The only thing I get is the check engine light goes on. Nothing else first I was told it’s a chafed wire but they couldn’t find it, now they tell me it’s the fuel lines both hi pressure and return which they ordered but are on back order. Can’t wait to see what’s next

Have them look in the left front where the harness comes from the ECM. I'm willing to put a small wager the casing on the harness has rubbed through and the wiring is all corroded and braking.

JP33 · May 5, 2022

28 minutes ago, Bassintodd said:

Have them look in the left front where the harness comes from the ECM. I'm willing to put a small wager the casing on the harness has rubbed through and the wiring is all corroded and braking.

Thanks

They had previously checked for chafed wire, I presume that’s at the ECM but not sure and found nothing so they recently did fuel hoses and so far so good. Hope so as I have a 1300 mile round trip road-trip planned soon.

Edited May 5, 2022 by JP33

JP33 · May 5, 2022

On 3/17/2022 at 3:07 PM, newdude said:

Thanks

they replaced the fuel hoses and it seems to have worked so far

If he still has that code and the dealer didn't follow the diag or the PI, then he needs to take it in and have them diag and follow the DTC and the PI.

#PIP5788A: DTC P2635 Set - (Apr 19, 2021)

Subject: DTC P2635 Set

Involved Region or Country

North America

Condition

Some customers may comment that the SES lamp is illuminated or was Illuminated and turned off, with no drivability concerns. During inspection Technician may notice DTC P2635.

Cause

Unknown at this time

Correction

If you encounter a vehicle with the above DTC, follow the applicable diagnostic flow chart in service information for further diagnosis and repair.

If the diagnostic does not isolate the concern, replace fuel feed pipe (fuel line between the high-pressure fuel pump and chassis line), clear the codes, and return it to the customer.

If the truck has already had the fuel jumper replaced, do not replace again. Follow diagnostic flow chart to ensure a different issue has not developed.

If it does not isolate the concern, clear codes only and return to the custom.

Engineering knows about the concern and is working on a more permanent service procedure.

This PI will be updated as information is gathered.

DTC P2635

Diagnostic Instructions

Perform the Diagnostic System Check prior to using this diagnostic procedure: Diagnostic System Check - Vehicle

Review the description of Strategy Based Diagnosis: Strategy Based Diagnosis

An overview of each diagnostic category can be found here: Diagnostic Procedure Instructions

DTC Descriptor

DTC P2635

Fuel Pump Flow Performance

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Control Circuit Shorted to Control Circuit

Control — Terminal 1 @ A6C Fuel Pump and Level Sensor Assembly - Primary

P102A

P1029

P102B

P102C, P2635

Control — Terminal 2 @ A6C Fuel Pump and Level Sensor Assembly - Primary

P102A

P1029

P102B

P102C, P2635

Control — Terminal 3 @ A6C Fuel Pump and Level Sensor Assembly - Primary

P102A

P1029

P102B

P102C, P2635

Circuit/System Description

For an overview of the component/system, refer to: Fuel System Description

Circuit

Description

Control

The output circuit varies between ground and 12 V.

Component

Description

G12 Fuel Pump

The component has a 3-phase motor. The control module converts the DC voltage from the battery to 3-phase AC to power the motor.

K111 Fuel Pump Driver Control Module

The control module K111 supplies the fuel pump with a PWM signal in order to achieve the desired fuel line pressure.

When the ignition is turned On, the ECM sends a 12 V signal to the control module K111 to enable the fuel pump. If the engine is not started, the control module K111 turns the fuel pump Off after 6 s.

Conditions for Running the DTC

DTC P018B, P018C, P018D, P0641, P064A, P0606, P1029, P102A, P102B, P102C, P1255, P129F, P12A6 = Not set

Fuel Pump Command = On

Ignition Voltage — 11 to 32 V

Engine Run Time — Greater than 30 s

Fuel Level Sensor — Greater than 10%

Frequency the DTC runs = Continuously — After the running conditions are met — For greater than 1 s

Conditions for Setting the DTC

The difference between the following parameters is greater than a predefined value:

Desired Fuel Pressure

Fuel Pressure Sensor

Actions Taken When the DTC Sets

DTCs listed in the DTC Descriptor Category = Type B DTC

Conditions for Clearing the DTC

DTCs listed in the DTC Descriptor Category = Type B DTC

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Master Electrical Component List

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections

Wiring Repairs

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References

Circuit/System Verification

Note: Do NOT replace the control module if DTC P2635 is set.

Ignition » On / Vehicle » In Service Mode

Verify DTC U0074, U18A2 is not set as a history DTC.If DTC U0074, U18A2 is set

Refer to: Diagnostic Trouble Code (DTC) List - Vehicle

If DTC U0074, U18A2 is not set

Verify DTC P018B, P018C, P018D, P0231, P0232, P023F is not set.If DTC P018B, P018C, P018D, P1029, P102A, P102B, P102C is set

Refer to: Diagnostic Trouble Code (DTC) List - Vehicle

If DTC P018B, P018C, P018D, P1029, P102A, P102B, P102C is not set

Perform the scan tool control function: Fuel Pressure » Increase — 300 kPa (43.5 PSI)

Verify the following parameters are within 45 kPa (6.5 PSI) of each other:

Desired Fuel Pressure

Fuel Pressure Sensor

If not within 45 kPa (6.5 PSI) of each other

Refer to: Fuel System Diagnosis

If within 45 kPa (6.5 PSI) of each other

Perform the scan tool control function: Fuel Rail Pressure » Increase — 400 kPa (58 PSI)

Verify the following parameters are within 60 kPa (8.7 PSI) of each other:

Desired Fuel Pressure

Fuel Pressure Sensor

If not within 60 kPa (8.7 PSI) of each other

Refer to: Fuel System Diagnosis

If within 60 kPa (8.7 PSI) of each other

Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

Verify the DTC does not set.If the DTC sets

Refer to: Fuel System Diagnosis

If the DTC does not set

All OK.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair: Diagnostic Repair Verification