DTC B2B02, B2B03, B2B0B, or B2B0C (LM2)
Diagnostic Instructions Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Review Strategy Based Diagnosis for an overview of the diagnostic approach. Diagnostic Procedure Instructions provides an overview of each diagnostic category. DTC Descriptors DTC B2B02 Blower Motor Speed Return Circuit High Voltage DTC B2B03 Blower Motor Speed Return Circuit Low Voltage DTC B2B0B Blower Motor Speed Feedback Circuit Out of Range High DTC B2B0C Blower Motor Speed Feedback Circuit Out of Range Low For symptom byte information refer to Symptom Byte List. Diagnostic Fault Information
| Circuit Number | Circuit Function | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performan |
|---|---|---|---|---|---|
| 2042 | B+ | B2B01 | B2B01 | — | — |
| 754 | Control | B2B01 | B2B01 | B2B00 | B2AFF |
| 761 | Signal | B2B02 | B2B02 | B2B03 | B2B0B, B2B0C |
| 1050 | Ground | — | 1 | — | — |
| 1. Blower Motor Malfunction |
Circuit/System Description The blower motor has a signal wire used to output a speed signal. The signal is monitored by the BCM, and the value is sent to the ECM via serial data. The ECM monitors the blower motor speed to modify the total commanded engine coolant flow rate, which is a percentage of available coolant flow sent to the heater core for occupant comfort and windshield defrosting. Conditions for Running the DTC B2B02, B2B03 System voltage = 9 – 16 V BCM is awake and communicating Blower motor is ON B2B0B, B2B0C System voltage = 9 – 16 V BCM is awake and communicating Blower motor is ON DTCs B2B02 or B2B03 are not set Conditions for Setting the DTC B2B02 The blower motor feedback circuit is out of range high The blower motor feedback signal duty cycle is between 0–10 % B2B03 The blower motor feedback signal is out of range low The blower motor feedback circuit duty cycle is between 90–100 % B2B0B The blower motor feedback signal frequency is out of range high The blower motor feedback signal frequency is greater than 224 Hz B2B0C The blower motor feedback signal frequency is out of range low The blower motor feedback signal frequency is less than 45 Hz Action Taken When the DTC Sets DTC Type B Conditions for Clearing the DTC DTC Type B Reference Information Schematic Reference HVAC Schematics Connector End View Reference Master Electrical Component List Description and Operation Automatic HVAC Description and Operation Electrical Information Reference Circuit Testing Connector Repairs Testing for Intermittent Conditions and Poor Connections Wiring Repairs DTC Type Reference Powertrain Diagnostic Trouble Code (DTC) Type Definitions Scan Tool Reference Control Module References for scan tool information Circuit/System Verification
- Ignition ON/ Vehicle in Service Mode.
- Verify the blower motor operates properly with the blower motor switch in each speed position. ⇒ If the blower motor does not operate properly in each speed position Refer to Blower Motor Malfunction. ⇓ If the blower motor operates properly in each speed position
- Verify DTC B2B02, B2B03 or B2B0C is not set. ⇒ If any of the DTCs are set Refer to Circuit/System Testing ⇓ If none of the DTCs are set
- Verify DTC B2B0B is not set. ⇒ If the DTC is set Replace the M8 Blower Motor. ⇓ If the DTC is not set
- A fault is not currently present and may be an intermittent condition. Circuit/System Testing
- Ignition OFF and all vehicle systems OFF, disconnect the connector at the M8 Blower Motor. It may take up to 2 min for all vehicle systems to power down. Ignition ON.
- Test for 4.8–5.2 V between the signal circuit terminal 3 and ground. ⇒ If less than 4.8 V 2.1. Test circuit 761 for a short to ground. ⇒ If a short to ground is found, repair the fault on the circuit. ⇓ If a short to ground is not found 2.2. Test circuit 761 for an open/high resistance. ⇒ If an open/high resistance is found, repair the fault on the circuit. ⇓ If an open/high resistance is not found 2.3. Replace the K9 Body Control Module ⇒ If greater than 5.2 V 2.1. Test circuit 761 for a short to voltage. ⇒ If a short to voltage is found, repair the fault on the circuit. ⇓ If a short to voltage is not found 2.2. Replace the K9 Body Control Module ⇓ If between 4.8–5.2 V
- Test or replace the M8 Blower Motor.
- Verify the DTC or symptom is corrected while operating the HVAC system under the Conditions for Running the DTC. ⇒ If the DTC or symptom is not corrected Replace the K9 Body Control Module. ⇓ If the DTC or symptom is corrected
- All OK. Repair Instructions Perform the Diagnostic Repair Verification after completing the repair. HVAC Component Replacement Reference Control Module References for control module replacement, programming and setup