Diagnostic Test

1) MAP SENSOR VOLTAGE BELOW 0.08 OF A VOLT
Ignition on, engine not running.

With a scan tool, read the MAP Sensor voltage.

Is the voltage below 0.08 of a volt?

Yes
1. Go To 2).
No
1. Refer to INTERMITTENT CONDITION .
2. Perform POWERTRAIN VERIFICATION TEST .
2) (F856) 5-VOLT SUPPLY CIRCUIT

Fig 1: Checking MAP Sensor 5-Volt Supply Circuit
Courtesy of DAIMLERCHRYSLER CORP.

Turn 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?

Yes
1. Go To 3).
No
1. Go To 6).
3) MAP SENSOR
With a scan tool, monitor the MAP Sensor voltage with the Sensor harness connector disconnected.

Is the voltage above 4.5 volts?

Yes
1. Replace the MAP Sensor.
2. Perform POWERTRAIN VERIFICATION TEST .
No
1. Go To 4).
4) (K1) MAP SIGNAL CIRCUIT SHORTED TO GROUND

Fig 2: Checking MAP Sensor Signal Circuit For Short To Ground
Courtesy of DAIMLERCHRYSLER CORP.

Turn the ignition off.

Disconnect the C2 PCM harness connector.

Measure the resistance between ground and the (K1) MAP Signal circuit in the MAP Sensor harness connector.

Is the resistance below 100 ohms?

Yes
1. Repair the short to ground in the (K1) MAP Signal circuit.
2. Perform POWERTRAIN VERIFICATION TEST .
No
1. Go To 5).
5) (K1) MAP SIGNAL CIRCUIT SHORTED TO THE (K900) SENSOR GROUND CIRCUIT

Fig 3: Checking Manifold Absolute Pressure Sensor Signal Circuit Shorted To Sensor Ground Circuit
Courtesy of DAIMLERCHRYSLER CORP.

Measure the resistance between the (K1) MAP Signal circuit and the (K900) Sensor ground circuit in the MAP Sensor harness connector.

Is the resistance below 100 ohms?

Yes
1. Repair the short between the (K900) Sensor ground and the (K1) MAP Signal circuit.
2. Perform POWERTRAIN VERIFICATION TEST .
No
1. Go To 8).
6) (F856) 5-VOLT SUPPLY CIRCUIT OPEN

Fig 4: Checking MAP Sensor 5-Volt Supply Circuit
Courtesy of DAIMLERCHRYSLER CORP.

Turn the ignition off.

Disconnect the C1 PCM harness connector.

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 (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?

Yes
1. Go To 7).
No
1. Repair the open in the (F856) 5-volt Supply circuit.
2. Perform POWERTRAIN VERIFICATION TEST .
7) (F856) 5-VOLT SUPPLY CIRCUIT SHORTED TO GROUND

Fig 5: Checking MAP Sensor 5-Volt Supply Circuit
Courtesy of DAIMLERCHRYSLER CORP.

Measure the resistance between ground and the (F856) 5-volt Supply circuit in the MAP Sensor harness connector.

Is the resistance below 100 ohms?

Yes
1. Repair the short to ground in the (F856) 5-volt Supply circuit.
2. Perform POWERTRAIN VERIFICATION TEST .
No
1. Go To 8).
8) 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
1. Repair as necessary.
2. Perform POWERTRAIN VERIFICATION TEST .
No
1. Replace and program the Powertrain Control Module per Service Information.
2. Perform POWERTRAIN VERIFICATION TEST .