Manual Three Zone Temperature Control
B210A-System Voltage Low
Theory of Operation
The A/C Heater Control constantly monitors battery and ignition voltage to ensure proper operation. If the voltage to the controller is out of range it could cause damage to the controller or its respective components. If the voltage of either circuit drops below or rises above a predetermined calibration a Diagnostic trouble Code (DTC) will set.
• When Monitored: With the ignition on.
• Set Condition: If the controller battery voltage is lower than 10.0 volts for period of five seconds.
Always perform the HVAC Pre-Diagnostic Troubleshooting procedure before proceeding. Refer to => Non-DTC Based Diagnostics. HVAC Pre-Diagnostic Troubleshooting Procedure
Test Step 1 - CHECK FOR CHARGING SYSTEM DTCS
• With the scan tool, read PCM DTCs.
Are there any charging system DTCs present in the Powertrain Control Module (PCM)?
Yes
• Perform the appropriate diagnostic procedure. Refer to => Electrical System DTC Based Diagnostics.
No
• Go to Test Step 2 => [ Test Step 2 - CHECK FOR TOTALLY INTEGRATED POWER MODULE DTCS ]
Test Step 2 - CHECK FOR TOTALLY INTEGRATED POWER MODULE DTCS
• With the scan tool, read TIPM DTCs.
Are there any TIPM DTCS present?
Yes
• Perform the appropriate diagnostic procedure. Refer to => Electrical System DTC Based Diagnostics.
No
• Go to Test Step 3 => [ Test Step 3 - CHECK IF THE DTC IS ACTIVE ]
Test Step 3 - CHECK IF THE DTC IS ACTIVE
• With the scan tool, read HVAC DTCs.
Is this DTC active?
Yes
• Go to Test Step 4 => [ Test Step 4 - CHECK THE (F921) FUSED IGNITION SWITCH OUTPUT (RUN)
CIRCUIT FOR AN OPEN ]
No
• Go to Test Step 7 => [ Test Step 7 - CHECK THE WIRING AND CONNECTORS ]
Test Step 4 - CHECK THE (F921) FUSED IGNITION SWITCH OUTPUT (RUN) CIRCUIT FOR AN OPEN
• Ignition on, engine not running.
• While back probing, measure the voltage of the (F921) Fused Ignition Switch Output (Run) circuit in the A/C Heater Control harness connector.
Is the voltage below 9.0 volts?
Yes
• Repair the (F921) Fused Ignition Switch Output (Run) circuit for an open or high resistance.
• Perform the HVAC Verification Test. Refer to => Non-DTC Based Diagnostics. HVAC Verification Test
• If the fuse is open, make sure to check for a short to ground on the (F921) Fused Ignition Switch Output (Run) circuit.
No
• Go to Test Step 5 => [ Test Step 5 - CHECK THE (A417) FUSED B(+) CIRCUIT FOR AN OPEN ]
Test Step 5 - CHECK THE (A417) FUSED B(+) CIRCUIT FOR AN OPEN
• While back probing, measure the voltage of the (A417) Fused B(+) circuit in the A/C Heater Control C1 harness connector.
Is the voltage below 9.0 volts?
Yes
• Repair the (A417) Fused B(+) circuit for an open or high resistance.
• Perform the HVAC Verification Test. Refer to => Non-DTC Based Diagnostics. HVAC Verification Test
• If the fuse is open, make sure to check for a short to ground on the (A417) Fused B(+) circuit.
No
• Go to Test Step 6 => [ Test Step 6 - CHECK THE (Z905) GROUND CIRCUIT FOR AN OPEN ]
Test Step 6 - CHECK THE (Z905) GROUND CIRCUIT FOR AN OPEN
• Turn the ignition off to the lock position.
• Disconnect the A/C Heater Control C1 harness connector.
• Using a 12-volt test light connected to 12-volts, check the (Z905) Ground circuit.
• The test light must illuminate brightly. Compare the brightness to that of a direct connection to the battery.
Does the test light illuminate brightly?
Yes
• Replace and program the A/C Heater Control.
• Perform the HVAC Verification Test. Refer to => Non-DTC Based Diagnostics. HVAC Verification Test
No
• Repair the (Z905) Ground circuit for an open.
• Perform the HVAC Verification Test. Refer to => Non-DTC Based Diagnostics. HVAC Verification Test
Test Step 7 - CHECK THE WIRING AND CONNECTORS
• The conditions necessary to set the DTC are not present at this time.
• With the scan tool, check the Environmental Data to help identify the conditions in which the DTC was set.
• 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.
• 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. Refer to => Non-DTC Based Diagnostics. HVAC Verification Test
No
• Test complete.