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 |
Diagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage |
|---|---|---|---|
Ignition 1 Voltage Circuit | 1 | 1 | -- |
Boost Gage Signal Circuit | 1 | 1 | -- |
Boost Gage Ground Circuit | -- | -- | 1 |
1. Boost gage inoperative | |||
Circuit/System Description
The boost gage is a measure of the engine manifold air pressure. The engine control module (ECM) sends a PWM signal to the boost gage via the boost gage signal circuit. The boost gage displays the engine air intake above and below the ambient manifold pressure. The ECM 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 gage is ON, the boost gage performs a power up self test. The boost gage dial normally below 0 kPa (0 psi) moves up to 0 kPa (0 psi) to indicate the boost gage passed the self test. Power is provided to the boost gage via the ignition 1 voltage circuit.
Reference Information
Schematic Reference
Connector End View Reference
Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the boost gage.
- Ignition OFF, test for less than 1 ohm of resistance between the boost gage ground circuit terminal D and ground.
- Ignition ON, verify a test lamp illuminates when connected between the boost gage B+ circuit terminal A and ground.
- Ignition OFF, connect the harness connector at the boost gage.
- Ignition ON, verify that the boost gage performs a self test by the gage dial moving up to the 0 kPa (0 psi) marker.
- If all circuits test normal, replace the boost gage.
| ⇒ | If greater than the specified range, test the circuit for a short to battery or open/high resistance. |
| ⇒ | 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, replace the ECM. |
| ⇒ | If the boost gage does not perform a self test, test the boost gage signal circuit terminal C for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for the ECM replacement, setup, and programming |
