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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 102 (Engine Controls - Self-Diagnostics - 3.5L) >> Diagnostic Tests >> DTC P0385: Crankshaft Position Sensor "B" Circuit >> Diagnostic Procedures

Diagnostic Procedures

WARNING: This page is about a different car, the 2002 Oldsmobile Intrigue and 2002 Oldsmobile Aurora. However, it is still accessible from the selected car via links, so may be relevant.
  1. Did you perform the Diagnostic System Check - Engine Controls? If yes, go to next step. If no, go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS  under SELF-DIAGNOSTIC SYSTEM.
  2. Attempt to start engine. If engine starts and runs, go to next step. If engine does not start, go to step  5.
  3. Ensure engine is idling. Using scan tool, monitor CKP sensor status parameter. If scan tool indicates CKP sensor status as ANGLE, go to next step. If scan tool does not indicate CKP sensor status as ANGLE, turn ignition off and go to step  5.
  4. Move the related harnesses and connectors by hand only, while monitoring the scan tool display. Does CKP Sensor Status change to Time "A" or to Time "B", or does an engine stall occur? If yes, go to step  12. If no, see DIAGNOSTIC AIDS .
    NOTE: The following steps apply to the sensor and related circuitry that is malfunctioning. For example, it scan tool indicates TIME A, system is using signal from CKP sensor "A". CKP sensor "B" and related circuits should be diagnosed.
  5. Turn ignition off. Disconnect CKP sensor harness connector. Turn ignition on. Using a Digital Multimeter (DMM) connected to ground, measure voltage on the 12-volt reference circuit at CKP sensor harness connector. Does the DMM indicate battery voltage? If yes, go to next step. If no, go to step  13.
  6. Connect DMM between the 12-volt reference circuit and low reference circuit in the CKP sensor harness connector. Does the DMM indicate battery voltage? If yes, go to next step. If no, go to step  14.
    NOTE: In the following step, PCM must be commanded to look at the CKP sensor being tested. Using scan tool, set CRANK POSITION SENSING DECODE MODE to TIME "A" if testing CKP sensor "A", or set mode to TIME "B" if testing CKP sensor "B".
  7. Turn ignition off and wait 15 seconds. Turn ignition on. Clear DTCs. Using scan tool, command the system to operate in the appropriate Time mode for the sensor being tested. Monitor the 24X Crank Sensor Data on scan tool. Using a test light connected to battery voltage, momentarily touch the signal circuit several times. Does scan tool indicate RPM? If yes, go to step  19. If no, go to next step.
  8. Turn ignition off. Disconnect PCM harness connector. Turn ignition on. Using DMM, check for voltage on the signal circuit. If voltage indicated? If yes, go to step  17. If no, go to next step.
  9. Using DMM, check signal circuit for continuity between the CKP sensor harness connector and PCM harness connector. Is reading 5 ohms or less? If yes, go to next step. If no, go to step  15.
  10. Using DMM, check for continuity between the signal circuit and ground. The DMM should display infinite resistance. Does DMM display infinite resistance? If yes, go to next step. If no, go to step  16.
  11. Using DMM, check for continuity between the CKP sensor "A" and CKP sensor "B" signal circuits. Does DMM display infinite resistance? If yes, go to step  21. If no, go to step  18.
  12. Repair damaged wiring harness and poor connections. After repairs, go to step  23.
  13. Check and repair the sensor 12-volt reference circuit. After repairs, go to step  23. If no problem is found, go to step  21.
  14. Check and repair open or high resistance in the low reference sensor circuit. After repairs, go to step  23. If no problem is found, go to step  21.
  15. Check and repair open or high resistance in the sensor signal circuit. After repairs, go to step  23. If no problem is found, go to step  21.
  16. Repair the sensor signal circuit that is shorted to ground. After repairs, go to step  23.
  17. Repair the sensor signal circuit that is shorted to power. After repairs, go to step  23.
  18. Repair the signal circuits that are shorted together. After repairs, go to step  23.
  19. Check for poor connections and for poor terminal tension at the CKP sensor. Repair as necessary. After repairs, go to step  23. If connector is okay, go to next step.
  20. Replace CKP sensor. After repairs, go to step  23.
  21. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to step  23. If connectors are okay, go to next step.
  22. Replace PCM. Program replacement PCM. See PROGRAMMING . After repairs, go to next step.
  23. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC. See CONDITIONS FOR RUNNING DTC . If DTC runs and passes, go to next step. If DTC resets, go to step  2.
  24. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, system is okay. If any other DTCs are set, repair DTCs as necessary. See DIAGNOSTIC TROUBLE CODE DEFINITIONS .
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