B1027

B1027-REAR BLOWER CONTROL REQUEST INPUT CIRCUIT/PERFORMANCE (ATC)





For a complete wiring diagram refer to Diagrams/Electrical.

- When Monitored:

With the ignition on.

- Set Condition:

If low and high rear blower speeds are requested simultaneously. This DTC has a maturing time of 5 seconds and a de-maturing time of 10 seconds. If the DTC's status changes from active to stored it will stay in memory for 100 ignition cycles.





NOTE: This DTC must be active for the results of this test to be valid. Do not perform this test if this DTC is stored. Refer to HVAC System Test (ATC) for stored DTC test procedures. HVAC System Test (ATC)

Diagnostic Test

1.CHECK VOLTAGE OF (C804) REAR BLOWER LOW CIRCUIT, (C803) REAR BLOWER MEDIUM CIRCUIT, & (C802) REAR BLOWER HIGH CIRCUIT





Turn the ignition off.

Disconnect the A/C Heater Control C2 harness connector.

Turn the ignition on.

Measure the voltage of the (C804) Rear Blower Low circuit.

Measure the voltage of the (C803) Rear Blower Medium circuit.

Measure the voltage of the (C802) Rear Blower High circuit.

Is the voltage above 0.2 volts on any of the circuits?

Yes

- Go To 2

No

- Go To 6

2.CHECK (C804) REAR BLOWER LOW CIRCUIT, (C803) REAR BLOWER MEDIUM CIRCUIT, & (C802) REAR BLOWER HIGH CIRCUIT FOR A SHORT TO VOLTAGE





Turn the ignition off.

Remove Junction Block Fuse 24.

Turn the ignition on.

Measure the voltage of the (C804) Rear Blower Low circuit.

Measure the voltage of the (C803) Rear Blower Medium circuit.

Measure the voltage of the (C802) Rear Blower High circuit.

Is the voltage above 0.2 volts on any of the circuits?

Yes

- Repair the circuit(s) with voltage above 0.2 volts for a short to voltage.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test

No

- Go To 3

3.CHECK (C804) REAR BLOWER LOW CIRCUIT FOR A SHORT TO (F504) FUSED IGNITION SWITCH OUTPUT (RUN) CIRCUIT





Turn the ignition off.

Disconnect the Rear A/C Heater Control harness connector.

Measure the resistance between the (C804) Rear Blower Low circuit and the (F504) Fused Ignition Switch Output (Run) circuit in the Rear A/C Heater Control harness connector.

Is the resistance below 10k ohms?

Yes

- Go To 4

No

- Go To 4

4.CHECK (C803) REAR BLOWER MEDIUM CIRCUIT FOR A SHORT TO (F504) FUSED IGNITION SWITCH OUTPUT (RUN) CIRCUIT





Measure the resistance between the (C803) Rear Blower Medium circuit and the (F504) Fused Ignition Switch Output (Run) circuit in the Rear A/C Heater Control harness connector.

Is the resistance below 10k ohms?

Yes

- Go To 5

No

- Go To 5

5.CHECK (C802) REAR BLOWER HIGH CIRCUIT FOR A SHORT TO (F504) FUSED IGNITION SWITCH OUTPUT (RUN) CIRCUIT





Measure the resistance between the (C802) Rear Blower High circuit and the (F504) Fused Ignition Switch Output (Run) circuit in the Rear A/C Heater Control harness connector.

Is the resistance below 10k ohms on any of the circuits tested in Steps 3, 4, & 5?

Yes

- Repair the circuit(s) with a resistance below 10k ohms for a short to the (F504) Fused Ignition Switch Output (Run) circuit.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test

No

- Go To 6

6.CHECK (C804) REAR BLOWER LOW CIRCUIT FOR A SHORT TO (C803) REAR BLOWER MEDIUM CIRCUIT





If not done so previously, turn the ignition off.

If not done so previously, disconnect the Rear A/C Heater Control harness connector.

Measure the resistance between the (C804) Rear Blower Low circuit and the (C803) Rear Blower Medium circuit in the Rear A/C Heater Control harness connector.

Is the resistance below 10k ohms?

Yes

- Go To 7

No

- Go To 7

7.CHECK (C804) REAR BLOWER LOW CIRCUIT FOR A SHORT TO (C802) REAR BLOWER HIGH CIRCUIT





Measure the resistance between the (C804) Rear Blower Low circuit and the (C802) Rear Blower High circuit in the Rear A/C Heater Control harness connector.

Is the resistance below 10k ohms?

Yes

- Go To 8

No

- Go To 8

8.CHECK (C803) REAR BLOWER MEDIUM CIRCUIT FOR A SHORT TO (C802) REAR BLOWER HIGH CIRCUIT





Measure the resistance between the (C803) Rear Blower Medium circuit and the (C802) Rear Blower High circuit in the Rear A/C Heater Control harness connector.

Is the resistance below 10k ohms on any of the circuits tested in Steps 6, 7, & 8?

Yes

- Repair the circuit(s) with a resistance below 10k ohms for a short to the other rear blower circuit(s).
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test

No

- Go To 9

9.CHECK FOR DTC B1027-REAR BLOWER CONTROL REQUEST INPUT CIRCUIT/PERFORMANCE WITH REAR A/C HEATER CONTROL DISCONNECTED

NOTE: Make sure that the Rear A/C Heater Control is disconnected.

Reconnect the A/C Heater Control C2 harness connector.

If removed, reinstall Junction Block Fuse 24.

Turn the ignition on.

With the scan tool, erase HVAC DTCs.

Turn the ignition off, wait 10 seconds, and then turn the ignition on.

Set the Rear Function mode switch to Control In Rear.

With the scan tool, read HVAC DTCs.

Does the scan tool display: B1027-REAR BLOWER CONTROL REQUEST INPUT CIRCUIT/PERFORMANCE?

Yes

- Replace the A/C Heater Control.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test

No

- Replace the Rear A/C Heater Control.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test