2007 Compass Patriot MK Factory Service Manual 9 - ENGINE

P0102-MASS AIR FLOW SENSOR CIRCUIT LOW

For a complete wiring diagram Refer to Section 8W

When Monitored:
No reference Voltage DTC's present. With the engine running and engine speed below 5100 rpm..
Set Condition:
The (K157) Mass Air Flow Sensor Signal is below the valid operating range for 1.0 second.

Possible Causes

INTERMITTENT DTC

(K157) MASS AIR FLOW SENSOR SIGNAL CIRCUIT OPEN OR HIGH RESISTANCE

(F855) MASS AIR FLOW SENSOR 5 VOLT SUPPLY CIRCUIT OPEN OR HIGH RESISTANCE

(K957) MASS AIR FLOW SENSOR GROUND CIRCUIT OPEN OR HIGH RESISTANCE

(K157) MASS AIR FLOW SENSOR SIGNAL CIRCUIT SHORTED TO GROUND

(K157) MASS AIR FLOW SENSOR SIGNAL CIRCUIT SHORTED TO THE (K957) MASS AIR FLOW SENSOR GROUND CIRCUIT

MASS AIR FLOW SENSOR

ENGINE CONTROL MODULE (ECM)

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)

Diagnostic Test

1. DTC IS ACTIVE

NOTE: If DTC P0652 or P0653 is present with this DTC, diagnose DTCs P0652 or P0653 before diagnosing this DTC.

Ignition on, engine not running.
With the scan tool, Clear DTCs in the Engine Control Module (ECM).
Start the engine and allow it to reach normal operating temperature.
With the scan tool, select View DTCs.

Is the status Active for this DTC?

Yes

Go To 2

No

Refer to the *CHECKING FOR AN INTERMITTENT DTC Diagnostic Procedure.

2. (K157) MASS AIR FLOW SENSOR SIGNAL CIRCUIT OPEN OR HIGH RESISTANCE

Turn the ignition off.
Disconnect the Mass Air Flow Sensor harness connector.
Disconnect the Engine Control Module (ECM) harness connector.
Measure the resistance of the (K157) Mass Air Flow Sensor Signal circuit between the Mass Air Flow Sensor connector and the Engine Control Module (ECM) harness connector.

Is the resistance below 10.0 ohms?

Yes

Go to 3

No

Repair the (K157) Mass Air Flow Sensor Signal circuit for an open circuit or high resistance.
Perform the ECM Verification Test Ver. 1. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)

3. (K957) MASS AIR FLOW SENSOR GROUND CIRCUIT OPEN OR HIGH RESISTANCE

Measure the resistance of the (K957) Mass Air Flow Sensor Ground circuit between the Mass Air Flow Sensor harness connector and the Engine Control Module (ECM) harness connector.

Is the resistance below 10.0 ohms?

Yes

Go to 4

No

Repair the (K957) Mass Air Flow Sensor Ground circuit for an open circuit or high resistance.
Perform the ECM Verification Test Ver. 1. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)

4. (F855) MASS AIR FLOW SENSOR 5 VOLT SUPPLY CIRCUIT OPEN OR HIGH RESISTANCE

Measure the resistance of the (F855) Mass Air Flow Sensor 5 Volt Supply circuit between the Mass Air Flow Sensor harness connector and the Engine Control Module (ECM) harness connector.

Is the resistance below 10.0 ohms?

Yes

Go to 5

No

Repair the (F855) Mass Air Flow Sensor 5 Volt Supply circuit for an open circuit or high resistance.
Perform the ECM Verification Test Ver. 1. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)

5. (K157) MASS AIR FLOW SENSOR SIGNAL CIRCUIT SHORTED TO GROUND

Measure the resistance between ground and the (K157) Mass Air Flow Sensor Signal circuit in the Mass Air Flow Sensor harness connector.

Is the resistance above 1000 ohms?

Yes

Go to 6

No

Repair the (K157) Mass Air Flow Sensor Signal circuit for a short to ground.
Perform the ECM Verification Test Ver. 1. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)

6. (K157) MASS AIR FLOW SENSOR SIGNAL CIRCUIT SHORTED TO THE (K957) MASS AIR FLOW SENSOR GROUND CIRCUIT

Measure the resistance between the (K157) Mass Air Flow Sensor Signal circuit and the (K957) Mass Air Flow Sensor Ground circuit in the Mass Air Flow Sensor harness connector.

Is the resistance above 1000.0 ohms?

Yes

Go to 7

No

Repair the (K157) Mass Air Flow Sensor Signal circuit for a short to the (K957) Mass Air Flow Sensor Ground circuit.
Perform the ECM Verification Test Ver. 1. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)

7. MASS AIR FLOW SENSOR

Turn the ignition off.
Connect the Engine Control Module (ECM) connector.
Replace the Mass Air Flow Sensor in accordance with the Service Information.
Turn the ignition on.
With the scan tool, Clear DTCs.
Start the engine and allow it to reach normal operating temperature.
With the scan tool, select View DTCs.

Is the status Active for this DTC?

Yes

Go to 8

No

Test Complete.
Perform the ECM Verification Test Ver. 1. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)

8. ENGINE CONTROL MODULE (ECM)

Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Mass Air Flow Sensor and the Engine Control Module (ECM).
Look for any chafed, pierced, pinched, or partially broken wires.
Look for broken, bent, pushed out or corroded terminals.
Monitor the scan tool data relative to this circuit and wiggle test the wiring and connectors.
Look for the data to change or for the DTC to reset during the wiggle test.
Refer to any Technical Service Bulletins that may apply.

Were any problems found?

Yes

Repair as necessary.

Perform the ECM Verification Test Ver. 1. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)

No

Replace the Engine Control Module (ECM) in accordance with the Service Information.
Perform the ECM Verification Test Ver. 1. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)