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Home >> GMC >> 2021 >> Terrain SLE, 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 247 (Automatic Transmission - 6T40 (MNH MNK) Or 6T45 (MHG) - Diagnostic Information And Procedures) >> Diagnostic Information and Procedures >> DTC P171A-P171C >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2021 Chevrolet Equinox. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition/Vehicle & All vehicle systems - Off
  2. Disconnect the electrical connector: B280 Automatic Transmission Accumulator Solenoid Valve
  3. Ignition - On / Vehicle - In Service Mode
  4. Verify a test lamp turns On between the test points: Ignition circuit terminal 1 & Ground
    • If the test lamp does not turn On and the circuit fuse is OK 
    1. Ignition/Vehicle - Off & Remove - Test lamp
    2. Test for less than 2 Ω between the test points: Ignition circuit terminal 1 & Output terminal @ F15UA Fuse
      • If 2 Ω or greater - Repair the open/high resistance in the circuit.
      • If less than 2 Ω - Verify the fuse is OK and there is voltage at the fuse.
    • If the test lamp does not turn On and the circuit fuse is open 
    1. Ignition/Vehicle - Off & Remove - Test lamp
    2. Test for infinite resistance between the test points: Ignition circuit terminal 1 & Ground
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • If infinite resistance - Replace the component: Automatic Transmission Auxiliary Fluid Accumulator
    • Go to next step: If the test lamp turns On 
  5. Verify a test lamp does not turn On between the test points: Control circuit terminal 2 & B+
    • If the test lamp turns On 
    1. Ignition/Vehicle - Off & Remove - Test lamp
    2. Disconnect the appropriate electrical connector: K20 Engine Control Module
    3. Test for infinite resistance between the test points: Control circuit terminal 2 @ Component harness & Ground
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • If infinite resistance - Replace the component: K20 Engine Control Module
    • Go to next step: If the test lamp does not turn On 
  6. Remove - Test Lamp
  7. Perform the scan tool control function: Autostart/Autostop - On

    Verify the scan tool parameter: Transmission Accumulator Solenoid Valve Control Circuit High Voltage Test Status = OK

    • If not the specified state 
    1. Ignition/Vehicle - Off
    2. Disconnect the appropriate electrical connector: K20 Engine Control Module
    3. Ignition - On / Vehicle - In Service Mode
    4. Test for less than 1 V between the test points: Control circuit terminal 2 @ Component harness & Ground
      • If 1 V or greater - Repair the short to voltage on the circuit.
      • If less than 1 V - Replace the component: K20 Engine Control Module
    • Go to next step: If the specified state 
  8. Connect a 3 A fused jumper wire between the test points: Control circuit terminal 2 & Ignition circuit terminal 1
  9. Perform the scan tool control function: Autostart/Autostop - On

    Verify the scan tool parameter: Transmission Accumulator Solenoid Valve Control Circuit High Voltage Test Status = Malfunction

    • If not the specified state 
    1. Ignition/Vehicle - Off & Remove - Jumper wire(s)
    2. Disconnect the appropriate electrical connector: K20 Engine Control Module
    3. Test for less than 2 Ω between the test points: Control circuit terminal 2 @ Component harness & The other end of the circuit @ Control module harness
      • If 2 Ω or greater - Repair the open/high resistance in the circuit.
      • If less than 2 Ω - Replace the component: K20 Engine Control Module
    • Go to next step: If the specified state 
  10. Test or replace the component: B280 Automatic Transmission Accumulator Solenoid Valve
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