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Home >> GMC >> 2006 >> Sierra 1500 HD, RWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 1342 (Hybrid Energy Storage System) >> Diagnostic Information and Procedures >> DTC P0C77 or P1A20 >> Component Testing >> Current Limit Relay Test

Current Limit Relay Test

WARNING: This page is about a different car, the 2009 GMC Sierra and 2009 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.
    WARNING: Before working on any high voltage system, be sure to wear the following Personal Protection Equipment:
    • Safety glasses with appropriate side shields when within 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 at all times when working with the high voltage battery assembly, whether the system is energized or not.

    Failure to follow the procedure exactly as written may result in serious injury or death.
  1. Ignition OFF, disable the high voltage at the drive motor generator battery. Refer to High Voltage Disabling .
  2. Remove the drive motor generator battery upper cover. Refer to Drive Motor Battery Case Upper Cover, Front Cover, and Right Side Cover Replacement .
  3. Remove the current limit relay.
  4. Test for 55-75 Ω between terminals 5 X1 and 6 X2.
    • If not within the specified range, replace the relay.
  5. Test for infinite resistance between the following terminals:
    • 1 X3 and 5 X1
    • 1 X3 and 2 X4
    • 1 X3 and 6 X2
    • 6 X2 and 2 X4
    • If not the specified value, replace the relay.
  6. Install a 20 A fused jumper wire between relay terminal 6 X2 and 12 V. Install a jumper wire between relay terminal 5 X1 and ground. Test for less than 2 Ω between terminals 1 X3 and 2 X4.
    • If greater than specified range, replace the relay.