2012 Jeep Wrangler JK Factory Service Manual 28 - DTC-Based Diagnostics

P2175-LOW AIRFLOW/RESTRICTION DETECTED (SLOW ACCUMULATION)

P2175-LOW AIRFLOW/RESTRICTION DETECTED (SLOW ACCUMULATION)

For a complete wiring diagram, refer to the Wiring Information.


Thoery of operation

The Electronic Throttle Control (ETC) motor is controlled by the Powertrain Control Module (PCM). The DC motor located in the throttle body drives the throttle blade. In order to decrease idle speed, along with spark and fuel delivery changes the PCM commands the throttle closed reducing air flow into the engine and the idle speed decreases. In order to increase idle speed, the PCM commands the throttle plate open allowing more air to pass the throttle plate.


Possible Causes

RESTRICTED AIR INLET SYSTEM
RESISTANCE IN THE (F856) 5-VOLT SUPPLY CIRCUIT
(F856) 5-VOLT SUPPLY CIRCUIT SHORTED TO GROUND
RESISTANCE IN THE (K1) MAP SIGNAL CIRCUIT
(K1) MAP SIGNAL CIRCUIT SHORTED TO GROUND
RESISTANCE IN (K900) SENSOR GROUND CIRCUIT
RESISTANCE IN THE (F855) 5-VOLT SUPPLY CIRCUIT
(F855) 5-VOLT SUPPLY CIRCUIT SHORTED TO GROUND
RESISTANCE IN THE TP SENSOR SIGNAL CIRCUIT
TP SENSOR SIGNAL CIRCUIT SHORTED TO GROUND
RESISTANCE IN THE (K922) TP SENSOR RETURN CIRCUIT
MAP SENSOR
TP SENSOR/THROTTLE BODY
POWERTRAIN CONTROL MODULE (PCM)

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).


1. ACTIVE DIAGNOSTIC TROUBLE CODE (DTC)



NOTE: The most likely cause of this DTC is a plugged intake air system or dirty Throttle Body. Check for any TSBs before continuing.

NOTE: Diagnose any 5-Volt Supply, TP Sensor, Oxygen Sensor, Fuel related or MAP Sensor DTCs before continuing.

NOTE: The throttle plate should be free from binding and carbon build up.

NOTE: Question the customer about weather conditions, as ice build up on the throttle blade can cause this fault when the ambient air temperature is in the -10°C (14°F) to 4°C (39°F) range.
1. Ignition on, engine not running.
2. With a scan tool, read the active DTCs.


Is the DTC Active at this time?

Yes


No


2. RESTRICTED AIR INLET SYSTEM

1. Turn the ignition off.
2. Remove the Air Cleaner Assembly.
3. Remove the Air Filter.
4. Inspect the Throttle Body opening for signs of any foreign materials.
5. Check the intake tube and air cleaner for obstructions; include snow packing questions to customer.


Were any restrictions found?

Yes


No


3. MAP SENSOR OPERATION

1. Start the engine.
2. With a scan tool, monitor the MAP Sensor voltage.
3. Snap the Accelerator pedal.


Does the MAP Sensor voltage vary from below 2.0 Volts at idle to above 3.5 Volts at Wide Open Throttle?

Yes


No


4. TP SENSOR OPERATION

1. Ignition on, engine not running.
2. With a scan tool, perform the Throttle Follower Test.
3. TP Sensor No.1 should start at approximately 0.7 of a Volt and increase to 4.3 Volts.
4. TP Sensor No.2 should start at approximately 4.3 Volts and decrease to 0.7 of a Volt.


Is the voltage transition smooth between the appropriate values?

Yes


No


5. RESISTANCE IN THE (F855) 5-VOLT SUPPLY CIRCUIT
1. Turn the ignition off.
2. Disconnect the Throttle Body harness connector.
3. Disconnect the PCM C2 harness connector.
4. Measure the resistance of the (F855) 5-Volt Supply circuit from the Throttle Body harness connector to the PCM C2 harness connector.


Is the resistance below 100 Ohms?

Yes


No


6. (F855) 5-VOLT SUPPLY CIRCUIT SHORTED TO GROUND
1. Measure the resistance between ground and (F855) 5-Volt Supply circuit at the Throttle Body harness connector.


Is the resistance above 100k Ohms?

Yes


No


7. TP SENSOR

1. Connect the PCM harness connector.
2. Ignition on, engine not running.
3. With a scan tool, monitor the TP Sensor voltage.
4. Connect a jumper wire between the (K22) TP Sensor No.1 Signal circuit and the (K922) TP Sensor Return circuit in the Throttle Body harness connector.
5. TP Sensor No.1 voltage should start at approximately 4.7 Volts and decrease to 0.3 of a Volt.
6. Connect a jumper wire between the (K122) TP Sensor No.2 Signal circuit and the (F855) 5-Volt Supply circuit in the Throttle Body harness connector.
7. TP Sensor No.2 voltage should start at approximately 0.3 Volts and increase to 4.7 Volts.


Does the TP Sensor voltage change to the appropriate voltage with the jumper wire installed?

Yes


No


8. RESISTANCE IN THE (K22) TP SENSOR NO.1 SIGNAL CIRCUIT
1. Turn the ignition off.
2. Disconnect the PCM C2 harness connector.
3. Measure the resistance of the (K22) TP Sensor No.1 Signal circuit from the Throttle Body harness connector to the PCM C2 harness connector.


Is the resistance below 5.0 Ohms?

Yes


No


9. RESISTANCE IN THE (K122) TP SENSOR NO.2 SIGNAL CIRCUIT
1. Measure the resistance of the (K122) TP Signal circuit from the Throttle Body harness connector to the PCM C2 harness connector.


Is the resistance below 5.0 Ohms?

Yes


No


10. (K22) TP SENSOR NO.2 SIGNAL CIRCUIT SHORTED TO GROUND
1. Measure the resistance between ground and the (K22) TP Sensor No.1 Signal circuit at the Throttle Body harness connector.


Is the resistance above 100k Ohms?

Yes


No


11. (K122) TP SENSOR NO.2 SIGNAL CIRCUIT SHORTED TO GROUND
1. Measure the resistance between ground and the (K122) TP Sensor No.2 Signal circuit at the Throttle Body harness connector.


Is the resistance above 100k Ohms?

Yes


No


12. RESISTANCE IN THE (K922) TP SENSOR RETURN CIRCUIT
1. Measure the resistance of the (K922) TP Sensor Return circuit from the Throttle Body harness connector to the PCM C2 harness connector.


Is the resistance below 5.0 Ohms?

Yes


No


13. RESISTANCE IN THE (F856) 5-VOLT SUPPLY CIRCUIT
1. Turn the ignition off.
2. Disconnect the MAP Sensor harness connector.
3. Disconnect the PCM C2 harness connector.
4. Measure the resistance of the (F856) 5-Volt Supply circuit from the MAP Sensor harness connector to the PCM C2 harness connector.


Is the resistance below 5.0 Ohms?

Yes


No


14. (F856) 5-VOLT SUPPLY CIRCUIT SHORTED TO GROUND
1. Measure the resistance between ground and the (F856) 5-Volt Supply circuit in the MAP Sensor harness connector.


Is the resistance above 100k Ohms?

Yes


No


15. MAP SENSOR
1. Connect the PCM C2 harness connector.
2. Ignition on, engine not running.
3. With a scan tool, monitor the MAP Sensor voltage.
4. Connect a jumper wire between the (K1) MAP Signal circuit and the (K900) Sensor ground circuit.
5. Cycle the ignition switch from off to on.
6. With a scan tool, monitor the MAP Sensor voltage.


Does the scan tool display MAP voltage from approximately 4.9 Volts to below 0.5 Volt with the jumper wire installed?

Yes


No


16. RESISTANCE IN THE (K1) MAP SIGNAL CIRCUIT
1. Turn the ignition off.
2. Disconnect the C2 PCM harness connector.
3. Measure the resistance of the (K1) MAP Signal circuit from the MAP Sensor harness connector to the PCM C2 harness connector.


Is the resistance below 5.0 Ohms?

Yes


No


17. (K1) MAP SIGNAL CIRCUIT SHORTED TO GROUND
1. Measure the resistance between ground and the (K1) MAP Signal circuit in the MAP Sensor harness connector.


Is the resistance above 100k Ohms?

Yes


No


18. RESISTANCE IN THE (K900) SENSOR GROUND CIRCUIT
1. Measure the resistance of the (K900) Sensor ground circuit from the MAP Sensor harness connector to the PCM C2 harness connector.


Is the resistance below 5.0 Ohms?

Yes


No


19. POWERTRAIN CONTROL MODULE (PCM)

1. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the MAP Sensor, Throttle Body, and the Powertrain Control Module (PCM).
2. Look for any chafed, pierced, pinched, or partially broken wires.
3. Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the MAP Sensor, Throttle Body, and Powertrain Control Module connectors.
4. Perform any Technical Service Bulletins that may apply.


Were there any problems found?

Yes


No