SYS.OK|MANUAL.DB● LIVE
HOMESERVICE MANUALSCHEVROLET2003TRAILBLAZER 4.2 S, 4WDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 1934 (ENGINE CONTROLS AND FUEL - 3.6L (LCS) - DTC P0008 TO DTC P0193)DTC P0191 (ECM)CIRCUIT/SYSTEM TESTING (ECM)
2003 Chevrolet TrailBlazer 4.2 S, 4WD

Circuit/System Testing (ECM)

2003 Chevrolet TrailBlazer 4.2 S, 4WDSECTION Circuit/System Testing (ECM)
WARNING: This page is about a different car, the 2009 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF, open the hood to disable the Auto-Stop function.
  2. Ignition ON, verify the scan tool hood position parameter displays Open.
    • If the hood position does not display Open, refer to DTC P254F .
  3. Ignition OFF, disconnect the multi-way harness connector X161 at the rear of the intake manifold.
  4. Remove the fuse that supplies B+ to terminal X2-56 of the ECM.
  5. Testing for steps 3 through 7 is performed on the ECM side of the multi-way harness connector.
  6. Ignition OFF, test for less than 5 Ξ© between the low reference circuit terminal 5 and ground.
    • If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
  7. Install the fuse that supplies B+ to terminal X2-56 of the ECM.
  8. Ignition ON, test for 4.8-5.2 V between the 5-volt reference circuit terminal 11 and ground.
    • If less than the specified range, test the 5-volt reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.
    • If greater than the specified range, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the ECM.
  9. Ignition ON, verify the scan tool FRP sensor voltage parameter is greater than 4.96 V.
    • If less than the specified value, test the signal circuit for a short to ground. If the circuit tests normal, replace the ECM.
  10. Connect a 3A fused jumper wire between the signal circuit terminal 12 and the low reference circuit terminal 5. Verify the scan tool FRP voltage parameter transitions from greater than 4.96 V to less than 0.02 V
    • If the parameter does not transition from the maximum to minimum value, test the signal circuit for an open/high resistance or a short to voltage. If the circuit tests normal, replace the ECM.
  11. Ignition OFF, remove the intake manifold.
  12. Disconnect the FRP sensor connector.
  13. Remove the fuse that supplies B+ to terminal X2-56 of the ECM.
  14. Testing for steps 11 through 15 are performed at the FRP sensor connector.
  15. Ignition OFF, test for less than 5 Ξ© between the low reference circuit terminal 2 and ground.
    • If greater than the specified range, test the low reference circuit for an open/high resistance.
  16. Install the fuse that supplies B+ to terminal X2-56 of the ECM.
  17. Ignition ON, test for 4.8-5.2 V between the 5-volt reference circuit terminal 3 and ground.
    • If less than the specified range, test the 5-volt reference circuit for a short to ground or an open/high resistance.
    • If greater than the specified range, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the ECM.
  18. Ignition ON, verify the scan tool FRP sensor voltage parameter is greater than 4.96 V.
    • If less than the specified value, test the signal circuit for a short to ground.
  19. Connect a 3A fused jumper wire between the signal circuit terminal 1 and the low reference circuit terminal 2. Verify the scan tool FRP voltage parameter transitions from greater than 4.96 V to less than 0.02 V
    • If the parameter does not transition from the maximum to the minimum value, test the signal circuit for an open/high resistance or a short to voltage.
  20. If all circuits test normal, replace the FRP sensor.
RENDER: 1.0x

NO RELATED

Recommended Tools & Savings

Use the Manual With the Right Hardware

Pair factory procedures with proven DIY tools so the instructions are easier to execute.

Affiliate disclosure: We may earn a commission at no extra cost to you.

Shop Manual-Ready ToolsFree Quote CheckQuote Shield Pro

When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • β€’ You smell fuel, burning insulation, or see smoke.
  • β€’ Brakes feel soft, pull hard to one side, or make grinding noises.
  • β€’ The engine overheats, stalls repeatedly, or misfires under load.
  • β€’ You are missing required tools, torque specs, or safe lifting equipment.
  • β€’ You are not confident in the next step or safety outcome.