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DTC B0174: Upper Left Air Temperature Sensor

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 numbers below refer to the step numbers of the diagnostic procedure.
  1. 2  - The operating range of the sensor is 0.09-4.90 volts. If the scan tool displays a value 0-0.08 volts or 4.91-5.0 volts, then the sensor is performing outside of its designed limits.
  2. 3  - Tests for the proper operation of the circuit in the high voltage range.
  3. 4  - Tests for the proper operation of the circuit in the low voltage range. If the fuse in the jumper opens when you perform this test, the signal circuit is shorted to voltage.
  1. Perform diagnostic system check. See DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM. After performing system check, go to next step.
  2. Connect scan tool and turn ignition on. Using scan tool, observe LEFT AC DUCT TEMP parameter in INSTRUMENT PANEL MODULE OPEN/SHORT data list. If scan tool indicates LEFT AC DUCT TEMP parameter is within 0.09-4.90 volts, inspect wiring and connectors for intermittent loose wires and/or poor connections. If scan tool indicates LEFT AC DUCT TEMP parameter is not within 0.09-4.90 volts, go to next step.
  3. Turn off ignition. Disconnect upper left air temperature sensor harness connector. Turn ignition on. Using scan tool, observe LEFT AC DUCT TEMP parameter in INSTRUMENT PANEL MODULE OPEN/SHORT data list. If scan tool indicates LEFT AC DUCT TEMP parameter is more than 4.90 volts, go to next step. If scan tool indicates LEFT AC DUCT TEMP parameter is 4.90 volts or less, go to step  5.
  4. Turn ignition off. Connect a jumper wire between terminals "A" (Black wire) and "B" (Yellow wire) of upper left air temperature sensor harness connector. See Figure. Turn ignition on. Using scan tool, observe LEFT AC DUCT TEMP parameter in INSTRUMENT PANEL MODULE OPEN/SHORT data list. If scan tool indicates LEFT AC DUCT TEMP parameter is 0.09 volts or less, check for loose wires and/or poor connections to upper left air temperature sensor. If wiring and connectors are okay, replace upper left air temperature sensor. See AIR TEMPERATURE SENSORS  under REMOVAL & INSTALLATION. Go to step  8. If scan tool indicates LEFT AC DUCT TEMP parameter is more than 0.09 volts, go to step  6.
  5. Check continuity between ground and terminal "A" (Black wire) of upper left air temperature sensor harness connector. If continuity exists, repair short to ground in Black wire between terminal B6 of Instrument Panel Module (IPM) and upper left air temperature sensor. See Figure. Go to step  8. If continuity does not exist, check for loose wires and/or poor connections at IPM. If wires and connections are okay, replace IPM. See INSTRUMENT PANEL MODULE (IPM)  under REMOVAL & INSTALLATION. Go to step  8.
  6. Check for voltage between ground and terminal "A" of upper left air temperature sensor. If voltage exists, repair short to voltage in Black wire between terminal B6 of Instrument Panel Module (IPM) and upper left air temperature sensor. Go to step  8. If voltage does not exist, go to next step.
  7. Check continuity in Yellow wire between terminal "B" of left air temperature sensor and terminal B8 of IPM. If continuity exists check for loose wires and/or poor connections at IPM. If wires and connections are okay, replace IPM. See INSTRUMENT PANEL MODULE (IPM)  under REMOVAL & INSTALLATION. Recalibrate IPM. Go to next step. If continuity does not exist, repair open or high resistance in Yellow wire. Go to next step.
  8. 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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