Boost Gauge Malfunction

Boost Gauge Malfunction

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 Instructions) provides an overview of each diagnostic category

Diagnostic Fault Information





Circuit/System Description

The boost gauge is a measure of the engine manifold air pressure. The powertrain control module (PCM) sends a PWM signal to the boost gauge via the boost gauge signal circuit. The boost gauge displays the engine air intake above and below the ambient manifold pressure. The PCM controls the engine boost pressure with the boost control solenoid. The engine boost system pumps more air than the engine would normally use into the intake manifold. The excess air pumped into the intake manifold, creates the engine boost effect. The maximum boost pressure is about 83 kPa (12 psi). When the ignition is turned ON and the boost gauge is ON, the boost gauge performs a power up self test as controlled by the PCM. The boost gauge dial moves up to 0 kPa (0 psi) to indicate the boost gauge passed the self test. Power is provided to the boost gauge via the ignition 1 voltage circuit.

Reference Information
Schematic Reference

* Instrument Cluster Schematics (Instrument Cluster Schematics)
* Engine Controls Schematics ([1][2]Electrical Diagrams)

Connector End View Reference

Component Connector End Views (Connector Views)
Description and Operation

* Instrument Cluster Description and Operation (Instrument Cluster)
* Boost Control System Description ()

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 Relearning)

Circuit/System Verification

Ignition ON, verify that the boost gauge performs a self test by the gauge dial moving up to the 0 kPa (0 psi) mark.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the boost gauge.
2. Ignition OFF, test for less than 5 ohms between the ground circuit terminal D and ground.

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

3. Ignition ON, verify a test lamp illuminates when connected between the B+ voltage circuit terminal A and ground.

• If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal, test or replace the BCM.

4. Ignition OFF, connect the harness connector at the boost gauge.
5. Ignition ON, verify that the boost gauge performs a self test by the gauge dial moving up to the 0 kPa (0 psi) mark.

• If the boost gauge does not perform a self test, test the boost gauge signal circuit terminal C for a short to ground or an open/high resistance. If the circuit tests normal, replace the PCM.

6. If all circuits test normal, replace the boost gauge.

Repair Instructions

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

* Turbocharger Pressure Power Indicator Replacement ()
* Control Module References (Programming and Relearning) for the PCM replacement, setup, and programming