Manual Temperature Control

B1028 - Rear Blower Control Request Input Circuit Low






For a complete wiring diagram, refer to.

• When Monitored: With the ignition on.

• Set Condition: If the A/C heater control detects voltage less than a calibrated value for a specified amount of time on the rear blower feed sense or the rear blend sense supply circuits.






• This DTC must be active for the results of this test to be valid. Do not perform this test if this DTC is stored.

Test Step 1 - Verify the DTC is Active

• Turn the ignition ON.

• With the scan tool, erase A/C heater control DTCs.

• Turn the ignition OFF, wait 10 seconds, and turn the ignition ON.

• With the scan tool, read A/C heater Control DTCs.

Does the scan tool display this DTC as active?

Yes

• Go to Test Step 2 => [ Test Step 2 - Check for an Active DTC with Rear Blower Control Switch
8 Way Harness Connector Disconnected ]

No

• Check for an intermittent condition by inspecting the related wiring harness for chafed, pierced, pinched, and partially broken wires. Also, inspect the related connectors for broken, bent, pushed out, spread, corroded, or contaminated terminals.

• Perform the HVAC Verification Test. Refer to => Non-DTC Based Diagnostics. HVAC Verification Test

Test Step 2 - Check for an Active DTC with Rear Blower Control Switch 8 Way Harness Connector Disconnected

• Turn the ignition OFF.

• Disconnect the rear blower control switch 8 way harness connector.

• Turn the ignition ON.

• With the scan tool, erase A/C heater control DTCs.

• Turn the ignition OFF, wait 10 seconds, and turn the ignition ON.

• With the scan tool, read A/C heater control DTCs.

Does the scan tool display this DTC as active?

Yes

• Go to Test Step 3 => [ Test Step 3 - Check the Rear Blower Feed Sense Circuit for a Short
to Ground ]

No

• Replace the rear blower control switch.

• Perform the HVAC Verification Test. Refer to => Non-DTC Based Diagnostics. HVAC Verification Test

Test Step 3 - Check the Rear Blower Feed Sense Circuit for a Short to Ground






• Turn the ignition OFF.

• Disconnect the A/C heater control C2 harness connector.

• Measure the resistance between ground and the Rear blower feed sense circuit in the A/C heater control C2 way harness connector.

Is the resistance less than 5.0 ohms?

Yes

• Repair the rear blower feed sense circuit for a short to ground.

• Perform the HVAC Verification Test. Refer to => Non-DTC Based Diagnostics. HVAC Verification Test

No

• Go to Test Step 4 => [ Test Step 4 - Check Rear Blend Sense Supply Circuit for a Short to
Ground ]
Test Step 4 - Check Rear Blend Sense Supply Circuit for a Short to Ground






• Measure the resistance between ground and the rear blend sense supply circuit in the A/C heater control C2 harness connector.

Is the resistance less than 5.0 ohms?

Yes

• Repair the rear blend sense supply circuit for a short to ground.

• Perform the HVAC Verification Test. Refer to => Non-DTC Based Diagnostics. HVAC Verification Test

No

• Go to Test Step 5 => [ Test Step 5 - Check the Rear Blower Feed Sense Circuit for an Open ]

Test Step 5 - Check the Rear Blower Feed Sense Circuit for an Open






• Measure the resistance of the rear blower feed sense circuit between the A/C heater control C2 harness connector and the rear blower control switch 8 way harness connector.

Is the resistance less than 5.0 ohms?

Yes

• Repair the rear blower feed sense circuit for an open.

• Perform the HVAC Verification Test. Refer to => Non-DTC Based Diagnostics. HVAC Verification Test

No

• Go to Test Step 6 => [ Test Step 6 - Check Rear Blend Sense Supply Circuit for an Open ]

Test Step 6 - Check Rear Blend Sense Supply Circuit for an Open






• Measure the resistance of the rear blend sense supply circuit between the A/C heater control C2 way and the rear A/C heater control switch 8 way harness connector.

Is the resistance less than 5.0 ohms?

Yes

• Repair the rear blend sense supply circuit for an open.

• Perform the HVAC Verification Test. Refer to => Non-DTC Based Diagnostics. HVAC Verification Test

No

• Replace the A/C heater control.

• Perform the HVAC Verification Test. Refer to => Non-DTC Based Diagnostics. HVAC Verification Test