Exhaust Brake Malfunction

Exhaust Brake Malfunction

Diagnostic Fault Information

Note: Always perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.

Typical Scan Tool Data





Circuit/System Description

The exhaust brake system is used to provide additional braking when the vehicle is decelerating. The engine control module (ECM) controls exhaust brake operation based on various sensor inputs. The ECM commands the turbocharger vane position to maximum boost for exhaust brake operation. Any malfunction of the Turbocharger or related engine controls hardware will set a powertrain DTC. If the exhaust brake does not function properly and there are no DTCs, the exhaust brake switch and related circuit should be diagnosed.

Reference Information

Schematic Reference

Exhaust System Schematics (Electrical Diagrams)

Connector End View Reference

Component Connector End Views (Connector End Views By Name)

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)

Circuit/System Verification

Ignition ON, observe the scan tool Exhaust Brake Switch parameter while depressing the Exhaust Brake switch several times. The reading should change between ON and OFF.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the exhaust brake switch.
2. Ignition OFF and all vehicle systems off. It may take up to 2 minutes for all vehicle systems to power down. Test for less than 5 ohm between the low reference circuit terminal 3 and ground.

• If greater than the specified range, test the low reference circuit for an open/high resistance.

3. Ignition ON, verify the scan tool Exhaust Brake Switch parameter is OFF.

• If not the specified value, test the signal circuit terminal 7 for a short to ground. If the circuit tests normal, replace the K20 ECM.

4. Install a 3 A fused jumper between the signal circuit terminal 7 and the ground circuit terminal 3. Verify the scan tool Exhaust Brake Switch parameter is ON.

• If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K20 ECM.

5. If all circuits test normal, test or replace the Exhaust Brake switch.

Component Testing

1. Ignition OFF, disconnect the harness connector at the exhaust brake switch.
2. Test for infinite resistance between the switch terminal 3 and terminal 7 with the switch in the open position.

• If not the specified range, replace the exhaust brake switch.

3. Test for less than 1 ohm between the switch terminal 3 and terminal 7 with the switch in the closed position.

• If greater than the specified value, replace the exhaust brake switch.

Repair Instructions

Note: Always perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

* Refer to Accessory Switch Replacement (without RPO SLT) (Accessory Switch Replacement (without RPO SLT))Accessory Switch Replacement (with RPO SLT) (Accessory Switch Replacement (with RPO SLT)) for Exhaust Brake Switch replacement.
* Control Module References (Control Module References)for ECM replacement, setup, and programming