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Diagnostic Procedure
1. Perform diagnostic system check. See DIAGNOSTIC SYSTEM CHECK under
TROUBLE SHOOTING. Go to next step.
2. Connect scan tool. Turn ignition on. Observe OUTSIDE AIR TEMP SENSOR in HVAC
data list. If scan tool indicates outside air temp sensor value is 0.1-5 volts, see
DIAGNOSTIC AIDS . If scan tool does not indicate outside air temp sensor value is 0.1-5
volts, go to next step.
3. Turn ignition off. Disconnect ambient air temperature sensor. Turn ignition on. Use scan
tool to observe OUTSIDE AIR TEMP SENSOR parameter. If scan tool indicates value is
more than 4.9 volts, go to next step. If scan tool indicates value is 4.9 volts or less, go to
step 5 .
4. Turn off ignition. Connect a fused jumper wire between terminals "A" (Light Green/Black
wire) and "B" (Gray/Black wire) of ambient air temperature sensor. Turn ignition on. Use
scan tool to observe OUTSIDE AIR TEMPERATURE SENSOR parameter. If scan tool
indicates 0.1 volt or more exists, go to step 6 . If scan tool indicates less than 0.1 volt exists,
go to step 8 .
5. Turn ignition off. Check continuity between ground and terminal "A" (Light Green/Black
wire) of ambient air temperature sensor. If continuity exists, repair short to ground in Light
Green/Black wire between ambient air temperature sensor and terminal D3 of HVAC
control head and go to step 12 . If continuity does not exist, go to step 9 .
6. Measure voltage between ground and terminal "A" (Light Green/Black wire) of ambient air
temperature sensor. If voltage exists, repair short to voltage in Light Green/Black wire
between ambient air temperature sensor and terminal D3 of HVAC control head harness
connector and go to step 12 . If voltage does not exist, go to next step.
7. Check continuity of Gray/Black wire between terminal "B" of ambient air temperature
sensor and terminal D1 of HVAC control head. If continuity exists, go to step 9 . If
continuity does not exist, repair open or high resistance in Gray/Black wire and go to step
12 .
8. Check wires and connectors at ambient outside air temperature sensor. Repair any problems
found and go to step 12 . If wiring and connectors are okay, go to step 10 .
9. Check for loose wires and or poor connections at HVAC control head. Repair any problems
found and go to step 12 . If wires and connectors are okay, go to step 11 .
10. Replace ambient air temperature sensor. See AMBIENT AIR TEMPERATURE
SENSOR under REMOVAL & INSTALLATION. After repairs, go to step 12 .
11. Replace HVAC control head. See HVAC CONTROL HEAD under REMOVAL &
INSTALLATION and go to next step.
12. Use scan tool to clear DTCs. See CLEARING TROUBLE CODES under SELF-
2001 Chevrolet Corvette
2000-01 AUTOMATIC A/C-HEATER SYSTEMS Corvette
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