B0460

DTC B0460 or B0462

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* Review Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions provide an overview of each diagnostic category.

DTC Descriptors

DTC B0460 00
- Coolant Heater Overheat Sensor Circuit Low

DTC B0462 00
- Coolant Heater Overheat Sensor Circuit Open

Diagnostic Fault Information






Circuit/System Description

The fuel operated coolant heater uses a coolant heater overheat sensor to protect the unit for over temperature conditions.

Conditions for Running the DTC

Engine is running.

Conditions for Setting the DTC

Fuel operated coolant heater has recognized out of range condition for more than 2.5 seconds.

Action Taken When the DTC Sets

Fuel operated coolant heater is disabled.

Conditions for Clearing the DTC

DTC must be cleared with a scan tool.


Circuit/System Verification

Start the vehicle. Observe the Overheat Temperature Sensor scan tool parameter. The scan tool parameter should display between 0.09-4.9 volts.

Component Testing

1. Ignition OFF, disconnect the harness connector at the coolant heater over temperature sensor.
2. Ignition OFF, test for less than1 ohm between the low reference circuit and ground.

^ If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the coolant heater.

3. Ignition ON, verify the scan tool Overheat Temperature Sensor parameter is greater than 4.5 volts.

^ If less than the specified range, test the signal circuit for a short to ground. If the circuit tests normal, replace the coolant heater.

4. Install a 3A fused jumper wire between the signal circuit and the low reference circuit. Verify the scan tool Overheat Temperature Sensor parameter is less than .5 volts.

^ If greater than the specified range, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the coolant heater.

5. If all circuits test normal, test or replace the over temperature sensor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests

Heater Coolant Heater Replacement