P1EC0
DTC P1EC0
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 P1EC0
- Hybrid/EV Battery System Contactor(s) Stuck Open
Circuit/System Description
At times, it may be necessary to disconnect high voltage from the vehicle, both during normal operation and when a system fault is identified. The Starter/Generator Control Module controls the Main Contactor and pre-charge contactor to disconnect and connect high voltage from the vehicle. The high voltage contactors are switches that are controlled much like a relay. To disable high voltage from the vehicle, the main and pre-charge contactors are commanded open. This will open the contactors and physically disconnect the hybrid/EV battery positive cable. To connect high voltage to the vehicle, first the pre-charge contactor is closed. With the pre-charge contactor closed, current flows through the pre-charge resistor. This allows high voltage to slowly build in the system, as the resistor decreases current flow. Once high voltage is brought up though the pre-charge contactor, the Main Contactor is close and high voltage is active. If the high voltage builds too quickly or too slowly, the Starter/Generator Control Module will set a fault.
Is a system fault occurs that does not allow the contactors to open, the Starter/Generator Control Module will be unable to disconnect high voltage from the vehicle. In instances such as this, the manual disconnect lever will disconnect high voltage from the vehicle when servicing.
Conditions for Running the DTC
Contactors are commanded closed
Conditions for Setting the DTC
The Starter/Generator Control Module does not detect high voltage after the contactors have been commanded closed.
Action Taken When the DTC Sets
DTC P1EC0 is a type A DTC.
Conditions for Clearing the DTC
DTC P1EC0 is a type A DTC.
Diagnostic Aids
* This diagnostic is used when high voltage has not been disabled when the contactors have been commanded closed. This indicates that one or both contactors are stuck open. The High Voltage Disabling procedure should still be completed, using the procedure for Servicing Any Internal Components Within the A4 Hybrid/EV Battery Pack. This will disconnect the battery terminals at the C4A Hybrid/EV Battery Section 1 and C4B Hybrid/EV Battery Section 2 and limit high voltage exposure when performing diagnosis.
* Be sure to check for any DTCs that may be set. These DTCs may lead to the cause of the stuck contactors and DTC diagnosis should be performed before enabling high voltage. This will help ensure a repeat fault with the contactors does not occur. After diagnosis any DTCs, return to this procedure to test and repair any contactor that may be mechanically stuck open.
Reference Information
Schematic Reference
Hybrid/EV Energy Storage Schematics [1][2]Battery System, Hybrid Drive
Connector End View Reference
Component Connector End Views Sunshade - Left
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 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.
Note: In High Voltage Disabling High Voltage Disabling, perform the disabling procedure for servicing components within the energy storage system. The C4A Hybrid/EV Battery Section 1 and C4B Hybrid/EV Battery Section 2 will be disconnected as part of the disabling procedure.
1. Ignition OFF, disable high voltage at the A4 Hybrid/EV Battery Pack. Refer to High Voltage Disabling High Voltage Disabling.
2. Verify DTC P0ADB, P0ADC, P0AE6, or P0AE7 is not set.
• If any of the DTCs are set
Refer to Diagnostic Trouble Code (DTC) List - Vehicle Diagnostic Trouble Code (DTC) List - Vehicle.
• If none of the DTCs are set
Note: The following steps will test the KR38 Main Contactor, KR134 Pre-Charge Contactor, and the S15 Manual Service Disconnect as a type of component test. These components must be removed from the A4 Hybrid/EV Battery Pack to ensure proper test results.
3. Remove the KR38 Main Contactor, KR134 Pre-Charge Contactor, and the S15 Manual Service Disconnect from the A4 Hybrid/EV Battery Pack.
4. Install a 10 A fused jumper wire between the KR38 Main Contactor B+ terminal 1 X1 and 12 V. Install a jumper wire between the KR38 Main Contactor control terminal 2 X1 and ground.
5. Test for less than 10 ohms between the high voltage terminals at the KR38 Main Contactor.
• If 10 ohms or greater
The KR38 Main Contactor is stuck in the open position. Replace the KR38 Main Contactor.
• If less than 10 ohms
6. Install a 10 A fused jumper wire between the KR134 Pre-Charge Contactor B+ terminal A X1 and 12 V. Install a jumper wire between the KR134 Pre-Charge Contactor control terminal A X2 and ground.
7. Test for less than 10 ohms between the high voltage terminals at the KR134 Pre-Charge Contactor.
• If 10 ohms or greater
The KR134 Pre-Charge Contactor is stuck in the open position. Replace the KR134 Pre-Charge Contactor.
• If less than 10 ohms
8. Test for less than 10 ohms between the high voltage terminals at the S15 Manual Service Disconnect with the lever in the closed position.
• If 10 ohms or greater
The S15 Manual Service Disconnect is stuck in the open position. Replace the S15 Manual Service Disconnect.
• If less than 10 ohms
9. Replace the K59 Starter/Generator Control Module.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the repair.
Control Module References Control Module References for Starter/Generator Control Module replacement, programming, and setup.