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Home >> GMC >> 2010 >> Terrain SLT, 2.4 W, AWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System & Fuel System - 2.2L Or 2.4L - DTC P1255 To DTC P2635 >> DTC P15A1 >> Circuit/System Testing

Circuit/System Testing

NOTE: You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.
  1. Ignition OFF, disconnect the X1 harness connector at the Fuel Economy Mode switch.
  2. Test for less than 5 Ω between the ground circuit terminal 1 of the harness connector and ground.
    • If greater than the specified range, test the ground circuit for a high resistance and repair as necessary.
  3. Measure between the 5 V reference voltage circuit terminal 3 of the switch and signal circuit terminal 4 of the switch for 266-294 Ω with a DMM.
    • If the DMM does not measure between 266-294 Ω, replace the S87 fuel economy mode switch.
  4. Measure between the 5 V reference voltage circuit terminal 3 of the switch and the ground circuit terminal 1 of the switch for 1,414-1,562 Ω with a DMM.
    • If the DMM does not measure between 1,414-1,562 Ω, replace the S87 fuel economy mode switch.
  5. With the fuel economy mode switch button depressed, measure between the 5 V reference voltage circuit terminal 3 of the switch and the ground circuit terminal 1 of the switch for 486-538 Ω with a DMM.
    • If the DMM does not measure between 486-538 Ω, replace the S87 fuel economy mode switch.
  6. Disconnect the X2 harness connector at the ECM.
  7. Measure the 5 V reference voltage circuit, between terminal 14 of the ECM harness connector and terminal 3 of the fuel economy mode switch harness connector, for less than 5 Ω.
    • If greater than the specified range, repair or replace the 5 V reference voltage circuit as necessary.
  8. Measure the signal circuit, between terminal 50 of the ECM harness connector and terminal 4 of the fuel economy mode switch harness connector, for less than 5 Ω.
    • If greater than the specified range, repair or replace the signal circuit as necessary.
  9. If all circuits test normal, replace the K20 ECM.
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