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FAULT CODE 221

Ambient Air Pressure Sensor Circuit

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Overview

CODE REASON EFFECT
Fault Code: 221
PID: P108
SPN: 108
FMI: 3
LAMP: Yellow
SRT: 00-094		 High voltage detected at ambient air pressure sensor signal pin 27 of the sensor harness connector. Engine power output derated by 15 percent.

Ambient Air Pressure Sensor Circuit

Circuit Description

The ambient air pressure sensor monitors atmospheric pressure and passes the information to the electronic control module (ECM) through the sensor harness.

Component Location

  • M11 – The ambient air pressure sensor is located on the engine block above the fuel supply pump.
  • 1994 N14 – The ambient air pressure sensor is located on the engine block to the right of the ECM.
  • 1991 N14 – The ambient air pressure sensor is located on the engine block to the left of the ECM.

Shop Talk

Monitor the ambient air pressure reading with a service tool to confirm that the pressure reading matches the actual air pressure.

Cautions and Warnings

 CAUTION 

 

To reduce the possibility of pin and harness damage, use the following test leads when taking a measurement:
Part Number 3822758 – male Deutsch/AMP/Metri-Pack test lead
Part Number 3822917 – female Deutsch/AMP/Metri-Pack test lead
Part Number 3824774 – breakout cable.
 CAUTION 

 

To reduce the possibility of damaging a new ECM, all other active fault codes must be investigated prior to replacing the ECM.
 CAUTION 

 

To reduce the possibility of pin and harness damage, use this breakout cable to perform the test procedure:
Part Number 3824774 – breakout cable.
 CAUTION 

 

To reduce the possibility of pin and harness damage, use this breakout cable to perform this test procedure:
Part Number 3824774 – breakout cable.
 CAUTION 

 

To reduce the possibility of pin and harness damage, use the following test lead when taking a measurement:
Part Number 3822917 – female Deutsch/AMP/Metri-Pack test lead.
 CAUTION 

 

To reduce the possibility of pin and harness damage, use the following test lead when taking a measurement:
Part Number 3822758 – male Deutsch/AMP/Metri-Pack test lead.
 CAUTION 

 

To reduce the possibility of pin and harness damage, use this test lead when taking a measurement:
Part Number 3822917 – Deutsch/AMP/Metri-Pack test lead.

Troubleshooting Steps

STEPS SPECIFICATIONS
STEP 1. Check the ambient air pressure sensor.
STEP 1A. Inspect the ambient air pressure sensor and sensor harness connector pins. No damaged pins
STEP 1B. Read the fault codes. Fault Code 221 active
STEP 1C. Check the ambient air pressure sensor supply voltage. 4.75 to 5.25 VDC
STEP 1C-1. Measure the ambient air pressure sensor supply voltage.
STEP 1C-2. Measure the voltage from the ECM.
STEP 1D. Check the ambient air pressure sensor signal voltage. 0 m [0 ft] (sea level) – 4.00 to 4.58, 914.4 m [3000 ft] – 3.60 to 4.40, 1828.8 m [6000 ft] – 3.20 to 4.00, 2743.2 m [9000 ft] – 3.00 to 3.80, 3657.6 m [12,000 ft] – 2.60 to 3.40
STEP 1D-1. Check for a short circuit from pin to pin.
STEP 1D-2. Check for continuity in the sensor harness.
STEP 1D-3. Check ECM response.
STEP 1D-4. Check ECM pin resistance.
STEP 2. Check the sensor harness.
STEP 2A. Inspect the sensor harness and the ECM connector for damaged pins. No damaged pins
STEP 2B. Read the fault codes. Fault Code 221 active
STEP 2C. Check for a short circuit from pin to pin. More than 100k ohms
STEP 3. Check for the ECM response.
STEP 3A. Check for the appropriate ECM response. Fault Code 221 inactive, Fault Code 222 active
STEP 3B. Check ECM signal pin resistance. Less than 100k ohms
STEP 4. Clear the fault codes.
STEP 4A. Disable the fault code. Fault Code 221 inactive
STEP 4B. Clear the inactive fault codes. All fault codes cleared

Guided Step 1 – Check the ambient air pressure sensor.

Guided Step 1A – Inspect the ambient air pressure sensor and sensor harness connector pins.

Conditions

  • Turn keyswitch OFF.
  • Disconnect the sensor harness from the ambient air pressure sensor.
  • Flush and clean the connector pins using electronic contact cleaner, Part Number 3824510.

Action

  • Bent or broken pins
  • Pushed back or expanded pins
  • Corroded pins
  • Moisture in or on the connector
  • Missing or damaged seals
  • Dirt or debris in or on the connector pins.
OK NOT OK
No damaged pins Repair the damaged pins.

  • Flush the dirt, debris, or moisture from the connector pins using electronic contact cleaner, Part Number 3824510.
  • Repair the sensor harness. Refer to Procedure 019-201, 019-202, or 019-205.
  • Replace the sensor harness. Refer to Procedure 019-043.
  • Replace the ambient air pressure sensor. Refer to Procedure 019-004.
  • Install the appropriate connector seal if it is damaged or missing. Refer to Procedure 019-201, 019-202, or 019-205.

Guided Step 1B – Read the fault codes.

Conditions

  • Turn keyswitch OFF.
  • Connect all components.

Action

  • Start the engine and let it idle for one minute.
  • Read the fault codes using INSITE™ electronic service tool.
OK NOT OK
Fault Code 221 active Repair complete.

 CAUTION 

 

To reduce the possibility of pin and harness damage, use this breakout cable to perform the test procedure:
Part Number 3824774 – breakout cable.
 CAUTION 

 

To reduce the possibility of pin and harness damage, use this breakout cable to perform this test procedure:
Part Number 3824774 – breakout cable.
 CAUTION 

 

To reduce the possibility of pin and harness damage, use the following test lead when taking a measurement:
Part Number 3822917 – female Deutsch/AMP/Metri-Pack test lead.
 CAUTION 

 

To reduce the possibility of damaging a new ECM, all other active fault codes must be investigated prior to replacing the ECM.
Guided Step 1C – Check the ambient air pressure sensor supply voltage.

Conditions

  • Disconnect all pressure and temperature sensors, and coolant level sensor or shorting plug, from the sensor harness.
  • Turn keyswitch ON.

Action

  • Install ambient air pressure sensor breakout cable, Part Number 3824774, between the sensor and the sensor harness connector.
  • Measure the supply voltage from pin A to pin B of the breakout cable.
OK NOT OK
4.75 to 5.25 VDC Does not meet specifications.

 CAUTION 

 

To reduce the possibility of pin and harness damage, use this breakout cable to perform this test procedure:
Part Number 3824774 – breakout cable.
Guided Step 1C-1 – Measure the ambient air pressure sensor supply voltage.

Conditions

  • Disconnect the sensor harness from the intake manifold pressure sensor.
  • Disconnect all pressure and temperature sensors, and the coolant level sensor or shorting plug, from the sensor harness.
  • Turn keyswitch ON.

Action

  • Install the ambient air pressure sensor breakout cable, Part Number 3824774, to the sensor connector on the sensor harness. Note: Do not connect the sensor to the breakout cable.
  • Measure the supply voltage from pin A to pin B of the breakout cable.
OK NOT OK
4.75 to 5.25 VDC

  • Replace the ambient air pressure sensor. Refer to Procedure 019-004.
 Does not meet specifications.

 CAUTION 

 

To reduce the possibility of pin and harness damage, use the following test lead when taking a measurement:
Part Number 3822917 – female Deutsch/AMP/Metri-Pack test lead.
 CAUTION 

 

To reduce the possibility of damaging a new ECM, all other active fault codes must be investigated prior to replacing the ECM.
Guided Step 1C-2 – Measure the voltage from the ECM.

Conditions

  • Disconnect the sensor harness connector from the ECM.
  • Turn keyswitch ON.

Action

  • Measure the voltage from pin 5 to pin 23 at the ECM sensor port.
OK NOT OK
4.75 to 5.25 VDC

  • Repair the sensor harness. Refer to Procedure 019-203.
  • Replace the sensor harness. Refer to Procedure 019-043.
 Replace the ECM. Refer to Procedure 019-031.

 CAUTION 

 

To reduce the possibility of pin and harness damage, use this breakout cable to perform this test procedure:
Part Number 3824774 – breakout cable.
 CAUTION 

 

To reduce the possibility of pin and harness damage, use the following test lead when taking a measurement:
Part Number 3822917 – female Deutsch/AMP/Metri-Pack test lead.
 CAUTION 

 

To reduce the possibility of pin and harness damage, use the following test lead when taking a measurement:
Part Number 3822758 – male Deutsch/AMP/Metri-Pack test lead.
 CAUTION 

 

To reduce the possibility of pin and harness damage, use the following test lead when taking a measurement:
Part Number 3822917 – female Deutsch/AMP/Metri-Pack test lead.
 CAUTION 

 

To reduce the possibility of damaging a new ECM, all other active fault codes must be investigated prior to replacing the ECM.
 CAUTION 

 

To reduce the possibility of pin and harness damage, use the following test lead when taking a measurement:
Part Number 3822917 – female Deutsch/AMP/Metri-Pack test lead.
 CAUTION 

 

To reduce the possibility of damaging a new ECM, all other active fault codes must be investigated prior to replacing the ECM.
Guided Step 1D – Check the ambient air pressure sensor signal voltage.

Conditions

  • Disconnect all sensors from the sensor harness, including the coolant level sensor or shorting plug.
  • Turn keyswitch ON.

Action

  • Install ambient air pressure sensor breakout cable, Part Number 3824774, between the sensor and the sensor harness connector.
  • Measure the signal voltage from pin C to pin B of the breakout cable.
OK NOT OK
0 m [0 ft] (sea level) – 4.00 to 4.58, 914.4 m [3000 ft] – 3.60 to 4.40, 1828.8 m [6000 ft ] – 3.20 to 4.00, 2743.2 m [9000 ft] – 3.00 to 3.80, 3657.6 m [12,000 ft] – 2.60 to 3.40 Does not meet specifications.

 CAUTION 

 

To reduce the possibility of pin and harness damage, use the following test lead when taking a measurement:
Part Number 3822917 – female Deutsch/AMP/Metri-Pack test lead.
Guided Step 1D-1 – Check for a short circuit from pin to pin.

Conditions

  • Turn keyswitch OFF.
  • Disconnect the sensor harness connector from the ECM.
  • Disconnect all pressure sensors and the coolant level sensor or shorting plug from their connectors.

Action

  • Measure the resistance from pin 5 to all other pins in the sensor harness connector at the ECM.
  • Measure the resistance from pin 23 to all other pins in the sensor harness connector at the ECM.
  • Measure the resistance from pin 27 to all other pins in the sensor harness connector at the ECM.
OK NOT OK
More than 100k ohms Repair or replace the sensor harness.

  • Repair the sensor harness. Refer to Procedure 019-203.
  • Replace the sensor harness. Refer to Procedure 019-043.

 CAUTION 

 

To reduce the possibility of pin and harness damage, use the following test lead when taking a measurement:
Part Number 3822758 – male Deutsch/AMP/Metri-Pack test lead.
Guided Step 1D-2 – Check for continuity in the sensor harness.

Conditions

  • Turn keyswitch OFF.
  • Disconnect the sensor harness connector from the ECM.
  • Disconnect the ambient air pressure sensor from the sensor harness.

Action

  • Measure the resistance from pin 5 of the sensor harness connector to pin A of the sensor connector.
  • Measure the resistance from pin 23 of the sensor harness connector to pin B of the sensor connector.
  • Measure the resistance from pin 27 of the sensor harness connector to pin C of the sensor connector.
OK NOT OK
Less than 10 ohms Repair or replace the sensor harness.

  • Repair the sensor harness. Refer to Procedure 019-203.
  • Replace the sensor harness. Refer to Procedure 019-043.

 CAUTION 

 

To reduce the possibility of pin and harness damage, use the following test lead when taking a measurement:
Part Number 3822917 – female Deutsch/AMP/Metri-Pack test lead.
 CAUTION 

 

To reduce the possibility of damaging a new ECM, all other active fault codes must be investigated prior to replacing the ECM.
Guided Step 1D-3 – Check ECM response.

Conditions

  • Disconnect sensor harness from ECM.
  • Turn keyswitch ON.

Action

  • Install Part Number 3822917, as a jumper wire, between ECM sensor harness port pin 27 and pin 23.
  • Read the fault codes.
OK NOT OK
Fault Code 221 inactive, Fault Code 222 active Fault Code 221 active

  • Replace ECM. Refer to Procedure 019-031.

 CAUTION 

 

To reduce the possibility of pin and harness damage, use the following test lead when taking a measurement:
Part Number 3822917 – female Deutsch/AMP/Metri-Pack test lead.
 CAUTION 

 

To reduce the possibility of damaging a new ECM, all other active fault codes must be investigated prior to replacing the ECM.
Guided Step 1D-4 – Check ECM pin resistance.

Conditions

  • Turn keyswitch OFF.
  • Disconnect the sensor harness connector from the ECM.

Action

  • Measure the resistance from pin 27 to pin 23 in the ECM; use test lead, Part Number 3822917.
OK NOT OK
Less than 100k ohms

  • Replace the sensor. Refer to Procedure 019-004.
 Greater than 100k ohms

  • Replace the ECM. Refer to Procedure 019-031.

Guided Step 2 – Check the sensor harness.

 CAUTION 

 

To reduce the possibility of damaging a new ECM, all other active fault codes must be investigated prior to replacing the ECM.
Guided Step 2A – Inspect the sensor harness and the ECM connector for damaged pins.

Conditions

  • Turn keyswitch OFF.
  • Disconnect the sensor harness connector from the ECM.
  • Flush and clean the connector pins using electronic contact cleaner, Part Number 3824510.

Action

  • bent or broken pins
  • pushed back or expanded pins
  • corroded pins
  • moisture in or on the connector
  • missing or damaged seals.
  • dirt or debris in or on the connector pins.
OK NOT OK
No damaged pins Repair the damaged pins.

  • Flush the dirt, debris, or moisture from the connector pins using electronic contact cleaner, Part Number 3824510.
  • Repair the sensor harness. Refer to Procedure 019-203.
  • Replace the sensor harness. Refer to Procedure 019-043.
  • Replace the ECM. Refer to Procedure 019-031.
  • Replace the o-ring on the 28-pin connector if it is damaged or missing. Refer to Procedure 019-203.

Guided Step 2B – Read the fault codes.

Conditions

  • Turn keyswitch OFF.
  • Connect all components.

Action

  • Start the engine and let it idle for one minute.
  • Read the fault codes using INSITE™ electronic service tool.
OK NOT OK
Fault Code 221 active Repair complete.

 CAUTION 

 

To reduce the possibility of pin and harness damage, use the following test lead when taking a measurement:
Part Number 3822758 – male Deutsch/AMP/Metri-Pack test lead.
Guided Step 2C – Check for a short circuit from pin to pin.

Conditions

  • Turn keyswitch OFF.
  • Disconnect the sensor harness connector from the ECM.
  • Disconnect all pressure sensors from the sensor harness.
  • Disconnect the coolant level sensor or shorting plug from the sensor harness.

Action

  • Measure the resistance from pin 5 of the sensor harness connector to all other pins in the connector.
  • Measure the resistance from pin 23 of the sensor harness connector to all other pins in the connector.
  • Measure the resistance from pin 27 of the sensor harness connector to all other pins in the connector.
OK NOT OK
More than 100k ohms Repair or replace the sensor harness.

  • Repair the sensor harness. Refer to Procedure 019-203.
  • Replace the sensor harness. Refer to Procedure 019-043.

Guided Step 3 – Check for the ECM response.

 CAUTION 

 

To reduce the possibility of pin and harness damage, use the following test lead when taking a measurement:
Part Number 3822917 – female Deutsch/AMP/Metri-Pack test lead.
 CAUTION 

 

To reduce the possibility of damaging a new ECM, all other active fault codes must be investigated prior to replacing the ECM.
Guided Step 3A – Check for the appropriate ECM response.

Conditions

  • Disconnect the sensor harness connector from the ECM.
  • Turn keyswitch ON.

Action

  • Install Part Number 3822917, as a jumper wire, between ECM sensor port pin 23 and pin 27.
  • Read the fault codes using INSITE™ electronic service tool.
OK NOT OK
Fault Code 221 inactive, Fault Code 222 active Replace the ECM. Refer to Procedure 019-031.

 CAUTION 

 

To reduce the possibility of pin and harness damage, use this test lead when taking a measurement:
Part Number 3822917 – Deutsch/AMP/Metri-Pack test lead.
Guided Step 3B – Check ECM signal pin resistance.

Conditions

  • Turn keyswitch OFF.
  • Disconnect the sensor harness connector from the ECM.

Action

  • Measure the resistance from pin 27 to pin 23 of the ECM sensor port;
    use test lead, Part Number 3822917.
OK NOT OK
Less than 100k ohms Replace the ECM. Refer to Procedure 019-031.

Guided Step 4 – Clear the fault codes.

Guided Step 4A – Disable the fault code.

Conditions

  • Connect all the components.

Action

  • Start the engine and let it idle for one minute.
  • Verify that Fault Code 221 is inactive.
OK NOT OK
Fault Code 221 inactive Return to troubleshooting steps or contact your nearest Cummins Authorized Repair Location if all steps have been completed and checked again.

Guided Step 4B – Clear the inactive fault codes.

Conditions

  • Connect all the components.

Action

  • Erase the inactive fault codes using INSITE™ electronic service tool.
OK NOT OK
All fault codes cleared Troubleshoot any remaining active fault codes.
Repair complete
Appropriate troubleshooting charts
Last Modified:  08-Sep-2004
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