Manual Temperature Control

B1143 - Mode Down Switch Performance

For a complete wiring diagram, refer to.

Theory of Operation

The switch input changes when the switch is pushed down. A stored DTC indicates that the mode down switch was stuck in a pushed position for more than 10 minutes, but has since returned to its normal state. An active DTC indicates that the mode down switch is stuck in a pushed position. When active, this DTC will prevent proper mode down switch and status indicator function.

• When Monitored: With the ignition on.

• Set Condition: If the mode down switch is detected in a pushed position for more than 10 minutes.






Test Step 1 - Inspect the A/C Heater Control for Damage

• Inspect the A/C heater control for damage.

Is the A/C heater control damaged?

Yes

• Replace the A/C heater control.

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

No

• Go to Test Step 2 => [ Test Step 2 - Inspect for an Object or Substance Causing the Mode
Down Switch to Stay or Stick in a Pushed Position ]

Test Step 2 - Inspect for an Object or Substance Causing the Mode Down Switch to Stay or Stick in a Pushed Position

• Inspect the A/C heater control for anything that would cause the mode down switch to stay or stick in a pushed position.

Is anything present that would cause the mode down switch to stay or stick in a pushed position?

Yes

• Repair as necessary.

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

No

• Go to Test Step 3 => [ Test Step 3 - Check for Normal Mode Down Switch and Status Indicator
Function ]

Test Step 3 - Check for Normal Mode Down Switch and Status Indicator Function

• Turn the ignition ON.

• Set the blower control to any position except off.

• Set the mode control to any position except auto.

• Press the mode down switch ON and OFF several times while observing the A/C status indicator.

Does the mode down switch indicator turn on and off?

Yes

• Go to Test Step 4 => [ Test Step 4 - Verify that the DTC is Still Active ]

No

• Replace the A/C heater control.

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

Test Step 4 - Verify that the DTC is Still Active

• With the scan tool, erase HVAC DTCs.

• Turn the ignition OFF, wait 10 seconds, and then turn the ignition ON. Wait 10 minutes before proceeding.

• With the scan tool, read HVAC DTCs.

Does the scan tool display this DTC?

Yes

• Replace the A/C heater control.

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

No

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