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Home >> Chevrolet >> 2002 >> Tracker 2D Utility, RWD, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System & Component Testing >> Idle Control System >> Electrical/Accessory Load Idle-Up Circuit Diagnosis >> Diagnostic Procedure
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Diagnostic Procedure

  1. Perform Diagnostic System Check - Engine Controls. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 2.0L TRACKER or SELF-DIAGNOSTICS - 2.5L TRACKER article. After performing Diagnostic System Check - Engine Controls, go to next step.
    2. NOTE: If headlights, HVAC blower motor, or rear defogger do not operate properly, diagnose those components first.
  2. Connect scan tool to Data Link Connector (DLC). Start and warm engine to normal operating temperature. Turn off all accessories. Using scan tool, monitor Engine Speed and IAC Motor Command parameters while turning each of the following accessories on and off:
    • Headlights
    • HVAC Blower Motor
    • Rear Window Defogger

    If scan tool indicates an increase in IAC Motor Command parameter when each accessory is turned on, go to next step. If scan tool does not indicate an increase in IAC Motor Command parameter when each accessory is turned on, go to step  20.

  3. Turn all accessories off. Turn A/C switch to ON position and blower speed selector switch to any position except OFF. Using scan tool, monitor Engine Speed and IAC Motor Command parameters while operating A/C system. If scan tool indicates an increase in IAC Motor Command parameter when A/C compressor is operating, go to next step. If scan tool does not indicate an increase in IAC Motor Command parameter when A/C compressor is operating, go to step  10.
  4. Turn all accessories off. Using scan tool, monitor Engine Speed and IAC Motor Command parameters while turning steering wheel fully right and left. If scan tool indicates an increase in IAC Motor Command parameter when turning steering wheel fully right and left, see SYMPTOM DIAGNOSIS under SYMPTOMS (GASOLINE) in TROUBLE SHOOTING - NO CODES - TRUCKS article. If scan tool does not indicate an increase in IAC Motor Command parameter when turning steering wheel fully right and left, go to next step.
  5. Turn all accessories off. Using scan tool, monitor power steering switch. Turn steering wheel fully right and left. If scan tool indicates "High Pressure" when steering wheel is turned fully in either direction, see IDLE AIR CONTROL SYSTEM DIAGNOSIS (2.0L)  or IDLE AIR CONTROL SYSTEM DIAGNOSIS (2.5L)  . If "High Pressure" is not indicated when steering wheel is turned fully in either direction, go to next step.
  6. Turn ignition on, engine off. Disconnect Power Steering Pressure (PSP) switch connector. PSP switch is located in upper left side of engine compartment, on power steering pump. Using DVOM, measure voltage from PSP switch connector (harness side) to ground. If battery voltage exists, go to next step. If battery voltage does not exist, go to step  8.
  7. Connect a test light to battery voltage. Probe PSP switch connector (switch side) with test light. Start engine. Observe test light while turning steering wheel fully to right and left. If test light illuminates when steering wheel was turned fully in either direction, go to DIAGNOSTIC AIDS . If test light does not illuminate when steering wheel was turned fully in either direction, go to step  9.
  8. Check for open or short to ground in PSP signal circuit (Blue/Orange wire) between PSP switch and PCM harness connector C2 terminal No. 7 (2.0L) or C1 terminal No. 26 (2.5L). See Figure or Figure . Repair as necessary. After repairs, go to step  30. If circuit is okay, go to step  29.
  9. Check for poor ground connection at power steering pump. Repair as necessary. After repairs, go to step  30. If circuit is okay, go to step  28.
  10. Using scan tool, monitor A/C Relay Command parameter. Turn A/C switch to ON position and blower speed selector switch to any position except OFF. If scan tool indicates ON when A/C compressor is operating, see IDLE AIR CONTROL SYSTEM DIAGNOSIS (2.0L)  or IDLE AIR CONTROL SYSTEM DIAGNOSIS (2.5L)  . If scan tool does not indicate ON when A/C compressor is operating, go to next step.
  11. Start engine. Turn A/C on (A/C operating). Using DVOM connected to ground, backprobe A/C idle-up circuit (Yellow/Black wire) at PCM connector C1 terminal No. 17 (2.0L) or C1 terminal No. 28 (2.5L). See Figure or Figure . If voltage is zero, go to next step. If voltage is not zero, go to step  14.
  12. Start engine. Turn A/C off. Using DVOM connected to ground, backprobe A/C idle-up circuit (Yellow/Black wire) at PCM connector C1 terminal No. 17 (2.0L) or C1 terminal No. 28 (2.5L). If battery voltage exists (2.0L) or 4.5-5.0 volts exists (2.5L), go to step  15. If voltage is not as specified, go to next step.
  13. Turn ignition off. Disconnect PCM connector C1. Back out A/C idle-up signal circuit (Yellow/Black wire) terminal No. 17 (2.0L) or terminal No. 28 (2.5L) from PCM connector. Reconnect harness connector C1 to PCM. Turn ignition on, engine off. Using DVOM connected to ground, backprobe through PCM connector slot to PCM terminal. Measure voltage. If battery voltage exists (2.0L) or 4.5-5.0 volts exists (2.5L), go to next step. If voltage is not as specified, go to step  29.
  14. Check for open or a short in A/C idle-up signal circuit between PCM and A/C compressor control module. Repair as necessary. After repairs, go to step  30. If circuit is okay, go to step  19.
  15. Start engine. Turn A/C off. Using DVOM connected to ground, backprobe A/C cut-out signal circuit (Gray/White wire) at PCM connector C1 terminal No. 8 (2.0L) or C1 terminal No. 27 (2.5L). See Figure or Figure . If voltage is zero, go to next step. If voltage is not zero, go to step  29.
  16. Start engine. Turn A/C on (A/C operating). Using DVOM connected to ground, backprobe A/C cut-out signal circuit (Gray/White wire) at PCM harness connector C1 terminal No. 8 (2.0L) or C1 terminal No. 27 (2.5L). If battery voltage exists, go to DIAGNOSTIC AIDS . If battery voltage does not exist, go to next step.
  17. Check for open or short to ground in A/C Cut-Out Signal circuit (Gray/White wire) between PCM and A/C compressor control module. Repair as necessary. After repairs, go to step  30. If circuit is okay, go to next step.
  18. Disconnect A/C compressor control module connector. Turn ignition on, engine off. Using DVOM, measure voltage between ground and A/C compressor control module harness connector terminal No. 8 (Green/Yellow wire). If battery voltage exists, go to step  29. If battery voltage does not exist, go to next step.
  19. A/C compressor control module is malfunctioning. Inspect A/C compressor control module and circuits for a fault. See MANUAL A/C-HEATER SYSTEMS - TRACKER article in AIR CONDITIONING & HEATING. Repair as necessary. After repairs, go to step  30.
  20. If scan tool indicated an increase in IAC Motor Command parameter when HVAC blower motor was turned on, go to step  22. If scan tool did not indicate an increase in IAC Motor Command parameter when HVAC blower motor was turned on, go to next step.
  21. Turn ignition off. Disconnect PCM connectors. Turn ignition on, engine off. Using test light connected to battery voltage, probe harness side of HVAC Blower Idle-Up circuit (Pink/White wire) at PCM harness connector C1 terminal No. 16 (2.0L) or C1 terminal No. 13 (2.5L). Observe test light while operating HVAC blower motor switch. If test light illuminates when HVAC blower motor switch is turned to ON position, go to step  29. If test light does not illuminate when HVAC blower motor switch is turned to ON position, go to step  25.
  22. If scan tool indicated an increase in IAC Motor Command parameter when rear window defogger switch was turned to ON position, go to next step. If scan tool did not indicate an increase in IAC Motor Command parameter when rear window defogger switch was turned to ON position, go to step  24.
  23. Using test light connected to ground, backprobe Electrical Load Idle-Up circuit (Red/Yellow wire) for exterior lights at PCM harness connector C1 terminal No. 32 (2.0L) or C1 terminal No. 29 (2.5L). See Figure or Figure . Observe test light while operating headlight switch. If test light illuminates when headlight switch is turned to ON position, go to step  29. If test light does not illuminate when headlight switch is turned to ON position, go to step  26.
  24. Using test light connected to ground, backprobe Electrical Load Idle-Up circuit (Black/Orange wire) for rear defogger at PCM harness connector C1 terminal No. 15. See Figure or Figure . Observe test light while operating rear defogger switch. If test light illuminates when rear defogger switch is turned to ON position, go to step  29. If test light does not illuminate when rear defogger switch is turned to ON position, go to step  27.
  25. Check for correct operation of HVAC Blower circuit. See MANUAL A/C-HEATER SYSTEMS - TRACKER article in AIR CONDITIONING & HEATING. Check HVAc Blower Idle-Up Signal circuit for open or short. Repair as necessary. After repairs, go to step  30. If all HVAC circuits are okay, go to step  29.
  26. Check for correct operation of exterior lighting. See EXTERIOR LIGHTS article in ACCESSORIES & EQUIPMENT. Check for open or short in Electrical Load Idle-Up circuit for exterior lights. Repair as necessary. After repairs, go to step  30. If Electrical Load Idle-Up circuit for exterior lights is okay, go to step  29.
  27. Check for correct operation of rear defogger. Check for open or short in Electrical Load Idle-Up circuit for rear defogger. See appropriate REAR WINDOW DEFOGGERS article in ACCESSORIES & EQUIPMENT. Repair as necessary. After repairs, go to step  30. If Electrical Load Idle-Up circuit for rear defogger is okay, go to step  29.
  28. Replace PSP switch. After repairs, go to step  30.
  29. Replace PCM. Perform PCM relearn procedures. See PROGRAMMING in SELF-DIAGNOSTICS - 2.0L TRACKER or SELF-DIAGNOSTICS - 2.5L TRACKER article. After repairs, go to next step.
  30. Operate vehicle within conditions under which original symptom was observed. System should operate properly. If system does not operate properly, see DIAGNOSTIC AIDS .
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