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P2174






P2174-LOW AIRFLOW/RESTRICTION DETECTED (INSTANTANEOUS ACCUMULATION)





For a complete wiring diagram refer to Diagrams/Electrical.


- When Monitored:

Ignition on and engine running with no MAP Sensor DTCs.

- Set Condition:

PCM calculated MAP value is greater than actual MAP value plus an offset value. One trip fault. Three good trips to turn of the mil. MIL is on and the ETC light will flash.







Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.


Diagnostic Test


1. ACTIVE 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, Fuel System Lean or Rich, 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 blade can cause this fault when ambient is around -10 to +4° C (14 to 39° F) range.

Ignition on, engine not running.

With a scan tool, select View DTCs.

Is the DTC Active at this time?

Yes

- Go To 2

No

- Refer to the INTERMITTENT CONDITION Diagnostic Procedure. Intermittent Condition


2. RESTRICTED AIR INLET SYSTEM

Turn the ignition off.

Remove the Air Cleaner Assembly.

Remove the Air Filter.

Inspect the Throttle Body opening for signs of any foreign materials.

Check the intake tube / air cleaner for obstructions - include snow packing questions to customer.

Were any restrictions found?

Yes

- Repair the restriction as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

No

- Go To 3


3. MAP SENSOR OPERATION

Start the engine.

With a scan tool, monitor the MAP Sensor voltage.

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

- Go To 4

No

- Go To 13


4. TP SENSOR OPERATION

Ignition on, engine not running.

With a scan tool, perform the Throttle Follower Test.

TP Sensor No.1 should start at approximately 0.8 of a volt and increase to 4.2 volts.

TP Sensor No.2 should start at approximately 4.2 volts and decrease to 0.8 of a volt.

Is the voltage transition smooth between the appropriate values?

Yes

- Refer to the INTERMITTENT CONDITION Diagnostic Procedure. Intermittent Condition

No

- Go To 5


5. RESISTANCE IN THE (K855) 5-VOLT SUPPLY CIRCUIT





Turn the ignition off.

Disconnect the Throttle Body harness connector.

Disconnect the C2 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 (K855) 5-volt Supply circuit from the Throttle Body harness connector to the appropriate terminal of special tool #8815.

Is the resistance below 100 ohms?

Yes

- Go To 6

No

- Repair the excessive resistance in the (K855) 5-volt Supply circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test


6. (K855) 5-VOLT SUPPLY CIRCUIT SHORTED TO GROUND





Measure the resistance between ground and (K855) 5-volt Supply circuit at the Throttle Body harness connector.

Is the resistance above 100k ohms?

Yes

- Go To 7

No

- Repair the short to ground in the (K855) 5-volt Supply circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test


7. TP SENSOR









Connect the PCM harness connectors.

Ignition on, engine not running.

With a scan tool, monitor the TP Sensor voltage.

Connect a jumper wire between the (K22) TP Signal 1 circuit and the (K922) TP Return circuit in the Throttle Body harness connector.

TP Sensor No.1 voltage should start at approximately 4.8 volts and decrease to 0.2 of a volt.

Connect a jumper wire between the (K122) TP Signal 2 circuit and the (K855) 5-volt Supply circuit in the Throttle Body harness connector.

TP Sensor No.2 voltage should start at approximately 0 volts and increase to 4.8 to 5.2 volts.

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

Yes

- Disconnect the Battery before replacing the Throttle Body Assembly. Replace the Throttle Body Assembly. After installation is complete, use a scan tool and select the ETC RELEARN function
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

No

- Go To 8


8. RESISTANCE IN THE (K22) TP SIGNAL 1 CIRCUIT





Turn the ignition off.

Disconnect the C2 PCM harness connector.

Measure the resistance of the (K22) TP Signal 1 circuits from the Throttle Body harness connector to the appropriate terminal of special tool #8815.

Is the resistance below 5.0 ohms?

Yes

- Go To 9

No

- Repair the excessive resistance in the (K22) TP Signal 1 circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test


9. RESISTANCE IN THE (K122) TP SIGNAL 2 CIRCUIT





Measure the resistance of the (K122) TP Signal 2 circuit from the Throttle Body harness connector to the appropriate terminal of special tool #8815.

Is the resistance below 5.0 ohms?

Yes

- Go To 10

No

- Repair the excessive resistance in the (K122) TP Signal 2 circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test


10. (K22) TP SIGNAL 1 CIRCUIT SHORTED TO GROUND





Measure the resistance between ground and the (K22) TP Signal 1 circuit at the Throttle Body harness connector.

Is the resistance above 100k ohms?

Yes

- Go To 11

No

- Repair the short to ground in the (K22) TP Signal 1 circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test


11. (K122) TP SIGNAL 2 CIRCUIT SHORTED TO GROUND





Measure the resistance between ground and the (K122) TP Signal 2 circuit at the Throttle Body harness connector.

Is the resistance above 100k ohms?

Yes

- Go To 12

No

- Repair the short to ground in the (K122) TP Signal 2 circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test


12. RESISTANCE IN THE (K922) TP RETURN CIRCUIT





Measure the resistance of the (K922) TP Return circuit from the Throttle Body harness connector to the appropriate terminal of special tool #8815.

Is the resistance below 5.0 ohms?

Yes

- Go To 19

No

- Repair the excessive resistance in the (K922) TP Return circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test


13. RESISTANCE IN THE (K857) 5-VOLT SUPPLY CIRCUIT





Turn the ignition off.

Disconnect the MAP Sensor harness connector.

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 (K857) 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

- Go To 14

No

- Repair the excessive resistance in the (K857) 5-volt Supply circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test


14. (K857) 5-VOLT SUPPLY CIRCUIT SHORTED TO GROUND





Measure the resistance between ground and the (K857) 5-volt Supply circuit in the MAP Sensor harness connector.

Is the resistance above 100k ohms?

Yes

- Go To 15

No

- Repair the short to ground in the (K857) 5-volt Supply circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test


15. MAP SENSOR





Connect the PCM harness connectors.

Ignition on, engine not running.

With a scan tool, monitor the MAP Sensor voltage.

Connect a jumper wire between the (K1) MAP Signal circuit and the (K900) Sensor ground circuit.

Cycle the ignition switch from off to on.

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

- Replace the MAP Sensor.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

No

- Go To 16
-
NOTE: Remove the jumper wire before continuing.


16. RESISTANCE IN THE (K1) MAP SIGNAL CIRCUIT





Turn the ignition off.

Disconnect the C2 PCM harness connector.

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 17

No

- Repair the excessive resistance in the (K1) MAP Signal circuit
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test


17. (K1) MAP SIGNAL CIRCUIT SHORTED TO GROUND





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

Is the resistance above 100k ohms?

Yes

- Go To 18

No

- Repair the short to ground in the (K1) MAP Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test


18. RESISTANCE IN (K900) SENSOR GROUND CIRCUIT





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 19

No

- Repair the excessive resistance in the (K900) Sensor ground circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test


19. 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 the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

No

- Replace and program the Powertrain Control Module.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
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