P0108

SYMPTOM
P0108-MANIFOLD ABSOLUTE PRESSURE SENSOR CIRCUIT HIGH

WHEN MONITORED
Engine speed between 600 to 3500 RPM. Battery voltage greater than 10.37 volts.

SET CONDITION
The MAP sensor signal voltage is greater than 4.92 volts for 3.0 seconds. One trip fault. Three good trips to turn off the MIL. (5.7L ETC light will flash).

POSSIBLE CAUSES
- (K1) MAP SIGNAL CIRCUIT SHORTED TO BATTERY VOLTAGE
- (K1) MAP SIGNAL CIRCUIT OPEN
- (K1) MAP SIGNAL CIRCUIT SHORTED TO THE (F856) 5-VOLT SUPPLY CIRCUIT
- (K900) SENSOR GROUND CIRCUIT OPEN
- MAP SENSOR
- PCM

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Scan Tool Testing and Procedures

DIAGNOSTIC TEST
1. MAP SENSOR VOLTAGE ABOVE 4.92 VOLTS





Start the engine.
With a scan tool, read the MAP Sensor voltage.
Is the voltage above 4.92 volts?
Yes>> Go To 2
No>> Perform (NGC) POWERTRAIN VERIFICATION TEST VER-5. Powertrain Verification Test - Ver 5

2. MAP SENSOR





Turn the ignition off.
Disconnect the MAP Sensor harness connector.
Connect a jumper wire between the (K1) MAP Signal circuit and the (K900) Sensor ground circuit in the Sensor harness connector.
Ignition on, engine not running.
With a scan tool, monitor the MAP Sensor voltage.
Is the voltage below 1.0 volt with the jumper wire installed?
Yes>> Replace the MAP Sensor. Perform (NGC) POWERTRAIN VERIFICATION TEST VER-5.
No>> Go To 3

Note: Remove the jumper wire before continuing.

3. (K1) MAP SIGNAL CIRCUIT SHORTED TO BATTERY VOLTAGE





Turn the ignition off.
Disconnect the PCM harness connectors.
Ignition on, engine not running.
Measure the voltage on the (K1) MAP Signal circuit in the MAP Sensor harness connector.
Is the voltage above 5.2 volts?
Yes>> Repair the short to battery voltage in the (K1) MAP Signal circuit. Perform (NGC) POWERTRAIN VERIFICATION TEST VER-5.
No>> Go To 4

4. (K1) MAP SIGNAL CIRCUIT OPEN





Turn the ignition off.

CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool # 8815 to perform diagnosis.

Measure the resistance of the (K1) MAP Signal circuit from the MAP Sensor harness connector to the appropriate terminal of special tool # 8815.
Is the resistance below 5.0 ohms?
Yes>> Go To 5
No>> Repair the open in the (K1) MAP Signal circuit. Perform (NGC) POWERTRAIN VERIFICATION TEST VER-5.

5. (K1) MAP SIGNAL CIRCUIT SHORTED TO THE (F856) 5-VOLT SUPPLY CIRCUIT





Measure the resistance between the (K1) MAP Signal circuit and the (F856) 5-volt Supply circuit in the MAP Sensor harness connector.
Is the resistance below 100 ohms?
Yes>> Repair the short between the (F856) 5-volt Supply circuit and the (K1) MAP Signal circuit. Perform (NGC) POWERTRAIN VERIFICATION TEST VER-5.
No>> Go To 6

6. (K900) SENSOR GROUND CIRCUIT OPEN





Measure the resistance of the (K900) Sensor ground circuit from the MAP Sensor harness connector to the appropriate terminal of special tool # 8815.
Is the resistance below 5.0 ohms?
Yes>> Go To 7
No>> Repair the open in the (K900) Sensor ground circuit. Perform (NGC) POWERTRAIN VERIFICATION TEST VER-5.

7. PCM

Note: Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary.

Using the schematics as a guide, inspect the wire harness and connectors. Pay particular attention to all Power and Ground circuits.
Were there any problems found?
Yes>> Repair as necessary. Perform (NGC) POWERTRAIN VERIFICATION TEST VER-5.
No>> Replace and program the Powertrain Control Module per Service Information. Perform (NGC) POWERTRAIN VERIFICATION TEST VER-5.