P1B3F
DTC P1B3F or P1B40
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.
DTC Descriptor
DTC P1B3F
- High Voltage System Interlock Circuit 2 Low Voltage
DTC P1B40
- High Voltage System Interlock Circuit 2 High Voltage
Diagnostic Fault Information
Circuit/System Description
The high voltage interlock circuits are utilized to verify high voltage component integrity. The high voltage interlock circuits are two circuit loops that passes through certain high voltage components. The high voltage interlock circuits are used to determine if access to high voltage components is being attempted. The opening of these high voltage components causes high voltage interlock circuit to open. The Starter/Generator Control Module monitors both the high voltage interlock 5 V reference circuit voltage and the high voltage interlock signal circuit voltage in order to detect circuit faults. When the Starter/Generator Control Module detects a loss of high voltage interlock circuit voltage, the high voltage contactors are commanded open.
The service cover for the Starter/Generator and the service cover for the Hybrid/EV Battery Pack each contain a high voltage interlock switch. When either cover is removed, the stater/generator control module will respond by opening the high voltage contacts. The 5 V reference circuits and signal circuits for each of the two high voltage interlock loops are completely separate from one another and are monitored as two separate loops, with each setting a specific DTC to indicate a circuit fault. The 5 V reference circuit that feeds the high voltage interlock switch on the Starter/Generator also supplies the 5 V reference to the brake pedal position sensor.
Conditions for Running the DTC
The Starter/Generator Control Module is awake and communicating
Conditions for Setting the DTC
DTC P1B3F
Voltage on the high voltage interlock signal circuit is less than 0.5 V
DTC P1B40
Voltage on the high voltage interlock signal circuit is grater than 4.5 V
Action Taken When the DTC Sets
DTCs P1B3F and P1B40 are type B DTCs
Conditions for Clearing the DTC
DTCs P1B3F and P1B40 are type B DTCs
Diagnostic Aids
* When a circuit fault is detected on the high voltage interlock loop that feeds the Starter/Generator and the vehicle hood is opened, the Starter/Generator Control Module will respond by turning off inverter switching. This will prevent the Starter/Generator from charging the Hybrid/EV Battery Pack and supplying voltage to the Starter/Generator Control Module 12 V output. Operating in this manner will cause an eventual discharge of both the high voltage battery pack and the 12 V battery.
* Because the 5 V reference circuit also supplies voltage to the brake pedal position sensor, a circuit fault on the high voltage interlock loop that feeds the Starter/Generator will also cause hybrid functions that rely on the brake pedal position, such as auto-stop and regenerative braking, to be disabled.
Reference Information
Schematic Reference
Hybrid Energy Storage Schematics [1][2]Battery System, Hybrid Drive
Connector End View Reference
Component Connector End Views Fuel Pump and Level Sensor Assembly
Description and Operation
Drive Motor Battery System Description Drive Motor Battery System Description
Electrical Information Reference
* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References Control Module References for scan tool information
Special Tools
EL-48900 - HEV Safety Kit
For equivalent regional tools, refer to Special Tools Tools and Equipment.
Circuit/System Verification
1. Ignition ON.
2. Verify DTC P0641 is not set.
• If the DTC is set
Refer to DTC P0641 Hybrid/EV Energy Storage.
• If the DTC is not set
3. Refer to Circuit/System Testing.
Circuit/System Testing
Danger: Always perform the High Voltage Disabling procedure prior to servicing any High Voltage component or connection. Personal Protection Equipment (PPE) and proper procedures must be followed.
The High Voltage Disabling procedure includes the following steps:
* Identify how to disable high voltage.
* Identify how to test for the presence of high voltage.
* Identify condition under which high voltage is always present and personal protection equipment (PPE) and proper procedures must be followed.
Before working on any high voltage system, be sure to wear the following Personal Protection Equipment:
* Safety glasses with appropriate side shields when within 15 meters (50 feet) of the vehicle, either indoors or outdoors.
* Certified and up-to-date Class "0" Insulation gloves rated at 1000V with leather protectors.
- Visually and functionally inspect the gloves before use.
- Wear the Insulation gloves with leather protectors at all times when working with the high voltage battery assembly, whether the system is energized or not.
Failure to follow the procedures may result in serious injury or death.
Danger: The eAssist battery pack assembly will utilize an exchange program. Please consult the most recent revision of bulletin/PI# PIC5520, available in Service Information (SI), for a list of approved eAssist battery pack assembly service procedures. Components that may be removed and serviced without exchanging the complete battery pack assembly are identified in the bulletin/PI. Please contact the GM Technical Assistance Center (1-877-446-8227) if you have any questions.
1. Ignition OFF, disconnect the X2 harness connector at the K59 Starter/Generator Control Module, ignition ON.
2. Test for less than 1 V between the following circuit terminals and ground:
* 5 V Reference circuit terminal 2
* Signal circuit terminal 1
• If 1 V or greater
1. Disconnect the harness connector at the A15 Starter/Generator.
2. Test for less than 1 V between the following circuit terminals and ground:
* K59 Starter/Generator Control Module 5 V reference circuit terminal 2 X2
* K59 Starter/Generator Control Module signal circuit terminal 1 X2
• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V
3. Replace the A15 Start/Generator.
• If less than 1 V
3. Ignition OFF.
4. Test for infinite resistance between the following circuit terminals and ground:
* 5 V Reference circuit terminal 2
* Signal circuit terminal 1
• If less than infinite resistance
1. Disconnect the harness connector at the A15 Starter/Generator.
2. Test for infinite resistance between the following circuit terminals and ground:
* K59 Starter/Generator Control Module 5 V reference circuit terminal 2 X2
* K59 Starter/Generator Control Module signal circuit terminal 1 X2
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance
3. Disable high voltage at the A4 Hybrid/EV Battery Pack. Refer to High Voltage Disabling High Voltage Disabling.
4. Remove the A15 Starter/Generator battery cable access cover.
Note: The 5 V reference and signal circuits pass through the A15 Starter/Generator and the A15 Starter/Generator battery cable block before connecting to a resistor located in the A15 Start/Generator battery cable access cover.
5. Verify the terminal integrity of the 5 V reference and signal circuits as they pass through the A15 Starter/Generator and the A15 Starter/Generator battery cable block. Verify none of these terminals are not damaged in a manner that would cause them to be shorted to ground.
• If any of the terminals are damaged, repair or replace the appropriate component as necessary.
• If none of the terminals are damaged.
6. Replace the A15 Start/Generator.
• If infinite resistance
5. Test for 2.5k - 3.5k ohms between the 5 V reference circuit terminal 2 and the signal circuit terminal 1.
• If less than 2.5k ohms
1. Disconnect the harness connector at the A15 Starter/Generator.
2. Test for infinite resistance between the K59 Starter/Generator Control Module 5 V reference circuit terminal 2 and the K59 Starter/Generator Control Module signal circuit terminal 1.
• If less than infinite resistance, repair the shorted together circuits.
• If infinite resistance
3. Connect the harness connector at the A15 Starter/Generator.
4. Disable high voltage at the A4 Hybrid/EV Battery Pack. Refer to High Voltage Disabling High Voltage Disabling.
5. Remove the A15 Starter/Generator battery cable access cover,
6. Test for infinite resistance between the K59 Starter/Generator Control Module 5 V reference circuit terminal 2 and the K59 Starter/Generator Control Module signal circuit terminal 1.
• If less than infinite resistance, verify the terminal integrity of the 5 V reference and signal circuits as they pass through the A15 Starter/Generator and the A15 Starter/Generator battery cable block. Verify these terminals are not damaged in a manner that would cause them to be shorted to together.
• If infinite resistance
7. Test the A15 Starter/Generator battery cable access cover. Refer to Component Testing.
• If the A15 Starter/Generator battery cable access cover does not pass the Component Test, replace the A15 Starter/Generator battery cable access cover.
• If the A15 Starter/Generator battery cable access cover passes the Component Test
8. Replace the A15 Starter/Generator.
• If greater than 3.5k ohms
1. Disconnect the harness connector at the A15 Starter/Generator.
2. Test for infinite resistance between the K59 Starter/Generator Control Module 5 V reference circuit terminal 2 and the K59 Starter/Generator Control Module signal circuit terminal 1.
• If less than infinite resistance, repair the shorted together circuits.
• If infinite resistance
3. Test for less than 2 ohms between the following circuit terminals:
* K59 Starter/Generator Control Module 5 V reference circuit terminal 2 X2 and the A15 Start/Generator 5 V reference circuit terminal 12
* K59 Starter/Generator Control Module signal circuit terminal 1 X2 and the A15 Start/Generator signal circuit terminal 11
• If 2 ohms or greater, repair the open circuit.
• If less than 2 ohms
4. Connect the harness connector at the A15 Starter/Generator.
5. Disable high voltage at the A4 Hybrid/EV Battery Pack. Refer to High Voltage Disabling High Voltage Disabling.
6. Remove the A15 Starter/Generator battery cable access cover.
7. Test the A15 Starter/Generator battery cable access cover. Refer to Component Testing.
• If the A15 Starter/Generator battery cable access cover does not pass the Component Test, replace the A15 Starter/Generator battery cable access cover.
• If the A15 Starter/Generator battery cable access cover passes the Component Test
Note: The 5 V reference and signal circuits pass through the A15 Starter/Generator and the A15 Starter/Generator battery cable block before connecting to a resistor located in the A15 Start/Generator battery cable access cover.
8. Verify the terminal integrity of the 5 V reference and signal circuits as they pass through the A15 Starter/Generator and the A15 Starter/Generator battery cable block. Verify none of these terminals are not damaged in a manner that would cause them to be open.
• If any of the terminals are damaged, repair or replace the appropriate component as necessary.
• If none of the terminals are damaged
9. Replace the A15 Starter/Generator.
• If between 2.5k - 3.5k ohms
6. Test or replace the K59 Starter/Generator Control Module
Component Testing
1. Ignition OFF, disable high voltage at the A4 Hybrid/EV Battery Pack. Refer to High Voltage Disabling High Voltage Disabling.
2. Remove the A15 Starter/Generator battery cable access cover.
3. Test for 2.5k-3.5k ohms between the A15 Starter/Generator battery cable access cover high voltage interlock 5 V reference terminal and the A15 Starter/Generator battery cable access cover high voltage interlock signal terminal.
• If not between 2.5k-3.5k ohms
Replace the A15 Starter/Generator battery cable access cover
• If between 2.5k-3.5k ohms
4. All OK.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the repair.
* Starter Generator Replacement Starter Generator Replacement
* Control Module References Control Module References for Starter/Generator Control Module replacement, programming, and setup