B046A
DTC B046A
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructionsprovides an overview of each diagnostic category.
DTC Descriptors
DTC B046A 02
- Auxiliary Heater Coolant Pump Temperature Circuit Short to Ground
DTC B046A 05
- Auxiliary Heater Coolant Pump Temperature Circuit Short to Battery or Open
Diagnostic Fault Information
Circuit Description
The HVAC control module supplies the temperature sensor with a low reference circuit and 5 V signal circuit. The HVAC control module determines the voltage drop across the sensor, which is proportional to temperature. As the temperature increases, the sensor resistance decreases and the voltage signal decreases. As the temperature decreases, the sensor resistance increases and the voltage signal increases.
Conditions for Running the DTC
The ignition is turned ON.
Conditions for Setting the DTC
The HVAC control module detects the temperature sensor signal circuit is less than -38°F or more than 185°F for more than 15 seconds.
Action Taken When the DTC Sets
A default value is used when the DTC is set.
Conditions for Clearing the DTC
* The DTC will become history if the HVAC control module no longer detects a failure.
* The history DTC will clear after 100 fault-free ignition cycles.
Reference Information
Schematic Reference
HVAC Schematics Electrical Diagrams
Connector End View Reference
Component Connector End Views Hybrid/EV Battery Pack X1
Description and Operation
Automatic HVAC Description and Operation HVAC - Automatic
Electrical Information Reference
* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs
Scan Tool Reference
Control Module References Programming and Relearningfor scan tool information
Circuit/System Testing
1. Vehicle OFF and all vehicle systems OFF, disconnect the harness connector at the B135 coolant heater temperature sensor. It may take up to 2 minutes for all vehicle systems to power down.
2. Test for less than 10 ohm between the low reference circuit terminal 2 and ground.
• If 10 ohm or greater
1. Vehicle OFF, disconnect the harness connector at the K33 HVAC control module.
2. Test for less than 2 ohm in the low reference circuit end to end.
• If 2 ohm or greater, repair the open/high resistance in the circuit.
• If less than 2 ohm, replace the K33 HVAC control module.
• If less than 10 ohm
3. Vehicle in Service Mode.
4. Verify the scan tool Heater Core Coolant Temperature Sensor parameter is less than -35°F.
• If -35°F or greater
1. Vehicle OFF, disconnect the harness connector at the K33 HVAC control module.
2. Test for infinite resistance between the signal circuit terminal 1 and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance, replace the K33 HVAC control module.
• If less than -35°F
5. Install a 3 A fused jumper wire between the signal circuit terminal 1 and the low reference circuit terminal 2.
6. Verify the scan tool Heater Core Coolant Temperature Sensor parameter is greater than 240°F.
• If 240°F or less
1. Vehicle OFF, disconnect the harness connector at the K33 HVAC control module, vehicle in Service Mode.
2. Test for less than 1 V between the signal circuit and ground.
• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V
3. Vehicle OFF.
4. Test for less than 2 ohm in the signal circuit end to end.
• If 2 ohm or greater, repair the open/high resistance in the circuit.
• If less than 2 ohm, replace the K33 HVAC control module.
• If greater than 240°F
7. Test or replace the B135 coolant heater temperature sensor.
Component Testing
1. Test the temperature sensor by varying the sensor temperature while monitoring the sensor resistance.
2. Compare the readings with the Temperature Versus Resistance Temperature Versus Resistance and verify that the resistance is within 5 percent of the specification.
• If not within the specified range, replace the sensor.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* HVAC Component Replacement Reference HVAC Component Replacement Reference
* Control Module References Programming and Relearningfor HVAC control module replacement, programming and setup