P0129-BAROMETRIC PRESSURE OUT-OF-RANGE LOWFor a complete wiring diagram Refer to Section 8W.When Monitored:With the ignition key on. No Cam or Crank signal within 75 ms. Engine speed less than 250 RPM.Set Condition:The PCM senses the voltage from the MAP sensor to be less than 2.2 volts but above 0.04 of a volt for 300 milliseconds. One Trip Fault. Three good trips to turn off the MIL. MIL is illuminated
and the ETC lamp will flash.
Possible Causes(F856) 5-VOLT SUPPLY CIRCUIT SHORTED TO BATTERY VOLTAGE(F856) 5-VOLT SUPPLY CIRCUIT OPEN(F856) 5-VOLT SUPPLY CIRCUIT SHORTED TO GROUND(K1) MAP SIGNAL CIRCUIT OPEN(K1) MAP SIGNAL CIRCUIT SHORTED TO GROUND(K1) MAP SIGNAL CIRCUIT SHORTED TO THE (K900) SENSOR GROUNDMAP SENSORPCM
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING). Diagnostic Test1.ACTIVE DTCIgnition on, engine not running.With a scan tool, select View DTCs.Is the DTC Active at this time.YesGo To 2NoRefer to the INTERMITTENT CONDITION Diagnostic Procedure.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)2.(F856) 5-VOLT SUPPLY CIRCUITTurn the ignition off.Disconnect the MAP Sensor harness connector.Ignition on, engine not running.Measure the voltage on the (F856) 5-volt Supply circuit in the MAP Sensor harness connector.Is the voltage between 4.5 to 5.2 volts?YesGo To 3NoGo To 73.MAP SENSORWith a scan tool, monitor the MAP Sensor voltage with the Sensor harness connector disconnected.Is the voltage above 2.2 volts?YesReplace the MAP Sensor.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)NoGo To 44.(K1) MAP SIGNAL CIRCUIT OPENTurn the ignition off.Disconnect the C2 PCM harness connector.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?YesGo To 5NoRepair the open in the (K1) MAP Signal circuit.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)5.(K1) MAP SIGNAL CIRCUIT SHORTED TO THE (K900) SENSOR GROUND CIRCUITMeasure the resistance between the (K900) Sensor ground circuit and the (K1) MAP Signal circuit in the MAP Sensor harness connector.Is the resistance below 5.0 ohms?YesRepair the short between the (K900) Sensor ground circuit and the (K1) MAP Signal circuit.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)NoGo To 66.(K1) MAP SIGNAL CIRCUIT SHORTED TO GROUNDMeasure the resistance between ground and the (K1) MAP Signal circuit in the MAP Sensor harness connector.Is the resistance below 100 ohms?YesRepair the short to ground in the (K1) MAP Signal circuit.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)NoGo To 107.(F856) 5-VOLT SUPPLY CIRCUIT SHORTED TO BATTERY VOLTAGETurn the ignition off.Disconnect the C1 PCM harness connector.Ignition on, engine not running.Measure the voltage on the (F856) 5-volt Supply circuit in the MAP Sensor harness connector.Is the voltage above 5.2 volts?YesRepair the short to battery voltage in the (F856) 5-volt Supply circuit.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)NoGo To 88.(F856) 5-VOLT SUPPLY CIRCUIT OPENTurn the ignition off.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 (F856) 5-volt Supply circuit from the MAP Sensor harness connector to the appropriate terminal of special tool #8815.Is the resistance below 5.0 ohms?YesGo To 9NoRepair the open in the (F856) 5-volt Supply circuit.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)9.(F856) 5-VOLT SUPPLY CIRCUIT SHORTED TO GROUNDMeasure the resistance between ground and the (F856) 5-volt Supply circuit in the MAP Sensor harness connector.Is the resistance below 100 ohms?YesRepair the short to ground in the (F856) 5-volt Supply circuit.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)NoGo To 1010.PCMBefore 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?YesRepair as necessary.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)NoReplace and program the Powertrain Control Module per Service Information.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)