B1915-11

B1915-11-FLOOR DUCT TEMPERATURE SENSOR - CIRCUIT SHORT TO GROUND





For a complete wiring diagram, refer to the Wiring Information.

Theory of Operation

The HVAC A/C Heater Control uses a variety of sensors to adjust HVAC operation to obtain optimal performance. These sensors are continuously monitored by the A/C Heater Control to assure that they are in range. An active Diagnostic Trouble Code (DTC) indicates that a sensor is out of range. A stored DTC indicates that the sensor was out of range but is currently within range.

The Floor Duct Temperature Sensor monitors the air temperature of the air from the panel duct and supplies an input signal to the A/C Heater Control. The Floor Duct Temperature Sensor resistance value will change in response to the air temperature from the panel duct. The resistance value is electronically transferred to the A/C Heater Control using a sensor ground circuit and a 5-volt reference signal circuit. Normal operation of the sensor the resistive value decreases when the panel duct air temperature decreases and the sensor resistive value increases when floor duct temperature increases.

- When Monitored:
Continuously with the ignition on.

- Set Condition:
The Floor Duct Temperature Sensor voltage input to the A/C Heater Control is less than 0.1 volts for a continuous period of 2.5 seconds. If the A/C Heater Control detects a valid voltage, the Diagnostic Trouble Code (DTC) will change from active to stored and will stay stored for 100 ignition cycles.





Always perform the HVAC Pre-Diagnostic Troubleshooting procedure before proceeding. Initial Inspection and Diagnostic Overview.

1. CHECK IF THE DTC IS ACTIVE
1. Ignition on, engine not running.
2. Using the scan tool, read HVAC DTCs.

Is this DTC active?

Yes

- Go To 2

No

- Go To 5

2. CHECK (C130) FLOOR DUCT TEMPERATURE SENSOR SIGNAL CIRCUIT FOR A SHORT TO GROUND
1. Turn the ignition off to the lock position.
2. Disconnect the A/C Heater Control C1 harness connector.
3. Disconnect the Floor Duct Temperature Sensor harness connector.
4. Measure the resistance between ground and the (C130) Floor Duct Temperature Sensor Signal circuit.

Is the resistance below 100k Ohms?

Yes

- Repair the (C130) Floor Duct Temperature Sensor Signal circuit for a short to ground.
- Perform the HVAC VERIFICATION TEST. HVAC Verification Test.

No

- Go To 3

3. CHECK (C130) FLOOR DUCT TEMPERATURE SENSOR SIGNAL CIRCUIT FOR A SHORT TO THE (C121) SENSOR GROUND CIRCUIT
1. Measure the resistance between the (C130) Floor Duct Temperature Sensor Signal circuit and the (C121) Sensor Ground circuit.

Is the resistance below 100k Ohms?

Yes

- Repair the (C130) Floor Duct Temperature Sensor Signal circuit for a short to (C121) Sensor Ground circuit.
- Perform the HVAC VERIFICATION TEST. HVAC Verification Test.

No

- Go To 4

4. CHECK THE FLOOR DUCT TEMPERATURE SENSOR
1. Replace the Floor Duct Temperature Sensor. Air Outlet Temperature Sensor - Removal.
2. With the scan tool, erase HVAC DTCs.
3. Cycle the ignition off for 30 seconds then back on.
4. With the scan tool, read HVAC DTCs.

Does this DTC reset?

Yes

- Replace and program the A/C Heater Control. A/C And Heater Control - Removal.
- Perform the HVAC VERIFICATION TEST. HVAC Verification Test.

No

- Test complete.
- Perform the HVAC VERIFICATION TEST. HVAC Verification Test.

5. CHECK THE WIRING AND CONNECTORS
1. The conditions necessary to set the DTC are not present at this time.
2. Using the scan tool, check the Environmental Data to help identify the conditions in which the DTC was set.
3. Using the wiring diagrams as a guide, check all related splices and connectors for signs of water intrusion, corrosion, pushed out or bent terminals, and correct pin tension.
4. Wiggle the wiring and connectors while checking for shorted and open circuits.

Were there any problems found?

Yes

- Repair as necessary.
- Perform the HVAC VERIFICATION TEST. HVAC Verification Test.

No

- Test complete.