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HOMESERVICE MANUALSCHEVROLET2001CHEVY EXPRESS G2500, VAN PASSENGER EXTENDED, 5.0 MREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 12 (HVAC SYSTEMS - AUTOMATIC)DIAGNOSTIC TESTSDTC B1000: LOSS OF COMMUNICATION TO INSTRUMENT PANEL MODULE (IPM)
2001 Chevrolet Chevy Express G2500, Van Passenger Extended, 5.0 M

DTC B1000: Loss Of Communication To Instrument Panel Module (IPM)

2001 Chevrolet Chevy Express G2500, Van Passenger Extended, 5.0 MSECTION DTC B1000: Loss Of Communication To Instrument Panel Module (IPM)
WARNING: This page is about a different car, the 2002 Oldsmobile Aurora. However, it is still accessible from the selected car via links, so may be relevant.
NOTE: The number below refers to the step number of the diagnostic procedure.
  1. 2  - The HVAC control module is inoperative when the module does not respond to any operator control requests.
  1. Perform diagnostic system check. See DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM. After performing system check, go to next step.
  2. Turn ignition on. If HVAC control head is inoperative, go to next step. If HVAC control head is not inoperative, inspect wiring and connectors for intermittent loose wires and/or poor connections.
  3. Turn ignition off. Disconnect HVAC control head. Turn ignition on. Measure voltage between ground and terminal A2 (Orange wire) of HVAC control head harness connector. If battery voltage exists, go to next step. If battery voltage does not exist, check continuity between ground and terminal A2 (Orange wire) of HVAC control head harness connector. If continuity exists, repair short to ground between terminal A2 (Orange wire) of HVAC control head and IGN 3 fuse (10-amp) of rear fuse box (located under rear seat on driver's side).
  4. Measure voltage between terminals A2 (Orange wire) and A1 (Black/White wire) of HVAC control head harness connector. If battery voltage exists, go to next step. If battery voltage does not exist, check continuity in Black/White between terminal A1 of HVAC control head and ground at right side of instrument panel.
  5. Turn ignition off. Disconnect HVAC control head. Turn ignition on. Measure voltage between ground and terminal No. B6 (Light Blue wire) of HVAC control head harness connector. If voltage is near one volt, go to next step. If voltage is not near one volt, go to step  7.
  6. Measure frequency between ground and terminal B5 (Purple wire) of HVAC control head harness connector. If frequency is near 930 Hertz, check for loose wires and/or poor connections at HVAC control head. Repair as necessary. If wiring and connectors are okay, replace HVAC control head. See HVAC CONTROL HEAD  under REMOVAL & INSTALLATION. Go to step  11. If frequency is not near 930 Hertz, go to step  9.
  7. Turn ignition off. Check for voltage between ground and terminal C12 (Light Blue wire) of Instrument Panel Module (IPM) harness connector. If voltage exists, repair short to voltage in Light Blue wire between IPM and terminal B6 of HVAC control head. Go to step  11. If voltage does not exist, go to next step.
  8. Check continuity in Light Blue wire between terminal C12 of IPM and terminal B6 of HVAC Control Module. See Figure. If continuity exists, check for loose wires and/or poor connections at IPM. If wiring and connectors are okay, replace IPM. See INSTRUMENT PANEL MODULE (IPM)  under REMOVAL & INSTALLATION. Go to step  11. If continuity does not exist, repair open or high resistance in Light Blue wire. Go to step  11.
  9. Check for voltage between ground and terminal C13 (Purple wire) of IPM harness connector C1. See Figure. If voltage exists, repair short to voltage in Purple wire between IPM and terminal B5 of HVAC control head. Go to step  11. If voltage does not exist, go to next step.
  10. Check continuity in Purple wire between terminal C13 (Purple wire) of IPM harness connector C1 and terminal B5 of HVAC control head. If continuity exists, voltage exists, check for loose wires and/or poor connections at IPM. If wiring and connectors are okay, replace IPM. See INSTRUMENT PANEL MODULE (IPM)  under REMOVAL & INSTALLATION. Go to next step. If continuity does not exist, repair open in Purple wire. Go to next step.
  11. Use scan tool to clear DTCs. Operate vehicle and verify that DTCs do not reset. If DTCs reset, return to step  2. If DTCs do not reset, system is okay.
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Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
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