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FAULT CODE 123

Intake Manifold Pressure Sensor Circuit

Printable Version  Printable Version

Overview

CODE REASON EFFECT
Fault Code: 123
PID: P102
SPN: 102
FMI: 4
LAMP: Yellow
SRT: 00-093		 Low voltage detected at the intake manifold pressure sensor signal pin 26 of sensor harness connector. Possible engine derate.

Intake Manifold Pressure Sensor Circuit

Circuit Description

The intake manifold pressure sensor monitors intake manifold pressure and passes information to the electronic control module (ECM) through the sensor harness. If intake manifold pressure becomes too low, it will cause a possible derate condition.

Component Location

The intake manifold pressure sensor is located on the intake air manifold.

Shop Talk

Check for high restriction in the intake air manifold because of a shutdown device in the manifold, if the vehicle is equipped with one.

Do not remove this device. If the engine is operated in a flammable atmosphere, the device is an essential safety feature. Removing it can cause severe personal injury or death.

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 3824776 – 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 the following test lead when taking a measurement:
Part Number 3824776 – 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 3822917 – female Deutsch/AMP/Metri-Pack.
 CAUTION 

 

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

 

To reduce the possibility of pin and harness damage, use this 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.

Troubleshooting Steps

STEPS SPECIFICATIONS
STEP 1. Check for multiple fault codes.
STEP 1A. Read the fault codes. Fault Codes 141, 145, 154, 213, 222, 352, and 422 are not active
STEP 2. Check for mechanical failure.
STEP 2A. Verify proper operation of the turbocharger. Positive intake manifold pressure from the turbocharger
STEP 3. Check the intake manifold pressure sensor.
STEP 3A. Inspect the intake manifold pressure sensor and sensor harness connector pins. No damaged pins
STEP 3B. Read the fault codes. Fault Code 123 active
STEP 3C. Check the intake manifold pressure sensor supply voltage. 4.75 to 5.25 VDC
STEP 3C-1. Check the intake manifold pressure sensor supply voltage.
STEP 3C-2. Measure the voltage out of the ECM.
STEP 3D. Check the intake manifold pressure sensor signal voltage. 0.42 to 0.58 VDC
STEP 3D-1. Check for a short circuit from pin to pin.
STEP 3D-2. Check for continuity in the sensor harness.
STEP 3D-3. Check ECM response.
STEP 3D-4. Check signal to return pin resistance.
STEP 4. Check the sensor harness.
STEP 4A. Inspect the sensor harness and the ECM connector for damaged pins. No damaged pins
STEP 4B. Read the fault codes. Fault Code 123 active
STEP 4C. Check for a short circuit to ground. More than 100k ohms
STEP 4D. Check for a short circuit from pin to pin. More than 100k ohms
STEP 4E. Check for continuity in sensor harness. Less than 10 ohms
STEP 4F. Clear and check the fault codes. Fault Code 123 inactive
STEP 5. Check for the ECM response.
STEP 5A. Check for an appropriate ECM response. Fault Code 123 inactive, Fault Code 122 active
STEP 5B. Check ECM signal pin resistance. Less than 100k ohms
STEP 6. Clear the fault codes.
STEP 6A. Disable the fault code. Fault Code 123 inactive
STEP 6B. Clear the inactive fault codes. All fault codes cleared

Guided Step 1 – Check for multiple fault codes.

Guided Step 1A – Read the fault codes.

Conditions

  • Turn keyswitch ON.

Action

  • Read the fault codes using INSITE™ electronic service tool.
OK NOT OK
Fault Codes 141, 145, 154, 213, 222, 352, and 422 are not active Possible sensor failure, short circuit to ground in sensor positive
(+) 5 VDC common supply, or short circuit from pin to pin.
Fault Code Multiple A

Guided Step 2 – Check for mechanical failure.

Guided Step 2A – Verify proper operation of the turbocharger.

Conditions

  • Turn keyswitch ON.
  • Start engine and let idle.

Action

  • Check for positive intake manifold pressure.
OK NOT OK
Positive intake manifold pressure from the turbocharger Low intake manifold pressure

  • Correct the base engine malfunction causing low intake manifold pressure. Refer to the base engine manual.

Guided Step 3 – Check the intake manifold pressure sensor.

Guided Step 3A – Inspect the intake manifold pressure sensor and sensor harness connector pins.

Conditions

  • Turn keyswitch OFF.
  • Disconnect the sensor harness from the intake manifold 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 or 019-202.
  • Replace the sensor harness. Refer to Procedure 019-043.
  • Replace the intake manifold pressure sensor. Refer to Procedure 019-061.
  • Install the appropriate connector seal if damaged or missing. Refer to Procedure 019-201 or 019-202.

Guided Step 3B – 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 123 active Repair complete.

 CAUTION 

 

To reduce the possibility of pin and harness damage, use the following test lead when taking a measurement:
Part Number 3824776 – breakout cable.
 CAUTION 

 

To reduce the possibility of pin and harness damage, use the following test lead when taking a measurement:
Part Number 3824776 – 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 3C – Check the intake manifold pressure sensor supply voltage.

Conditions

  • Connect sensor harness connector to ECM.
  • Disconnect all pressure and temperature sensors from their connectors on the sensor harness, except for the intake manifold pressure sensor.
  • Disconnect the coolant level sensor or shorting plug from its connector.
  • Turn keyswitch ON.

Action

  • Install the intake manifold pressure sensor breakout cable, Part Number 3824776, 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 the following test lead when taking a measurement:
Part Number 3824776 – breakout cable.
Guided Step 3C-1 – Check the intake manifold pressure sensor supply voltage.

Conditions

  • Connect sensor harness connector to ECM.
  • Disconnect all pressure and temperature sensors from their connectors on the sensor harness.
  • Disconnect the coolant level sensor or shorting plug from its connector.
  • Turn keyswitch ON.

Action

  • Install the intake manifold pressure sensor breakout cable, Part Number 3824776, to the sensor harness connector.

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 intake manifold pressure sensor. Refer to Procedure 019-061.
 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 3C-2 – Measure the voltage out of the ECM.

Conditions

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

Action

  • Measure the voltage out of the ECM from pin 2 to pin 4 at the ECM sensor port.
OK NOT OK
4.75 to 5.25 VDC

  • 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 the following test lead when taking a measurement:
Part Number 3824776 – 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.
 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.
 CAUTION 

 

To reduce the possibility of pin and harness damage, use this test lead when taking a measurement:
Part Number 3822917 – female Deutsch/AMP/Metri-Pack.
 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 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 3D – Check the intake manifold pressure sensor signal voltage.

Conditions

  • Connect the sensor harness connector to the ECM.
  • Disconnect all pressure and temperature sensors from their connectors on the sensor harness.
  • Connect the intake manifold sensor to the breakout cable.
  • Turn keyswitch ON.

Action

  • Install the intake manifold pressure sensor breakout cable, Part Number 3824776, 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
0.42 to 0.58 VDC 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.
Guided Step 3D-1 – Check for a short circuit from pin to pin.

Conditions

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

Action

  • Measure the resistance from pin 26 of the sensor harness to all other pins in the ECM connector.
  • Measure the resistance from pin 4 of the sensor harness to all other pins in the ECM connector.
  • Measure the resistance from pin 2 of the sensor harness to all other pins in the ECM 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.

 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.
Guided Step 3D-2 – Check for continuity in the sensor harness.

Conditions

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

Action

  • Measure the resistance from pin 2 of the sensor harness connector to pin A of the sensor connector.
  • Measure the resistance from pin 26 of the sensor harness connector to pin C of the sensor connector.
  • Measure the resistance from pin 4 of the sensor harness connector to pin B of the sensor connector.
OK NOT OK
Less than 10 ohms Correct pin-to-pin wiring or open circuit.

  • 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 this test lead when taking a measurement:
Part Number 3822917 – female Deutsch/AMP/Metri-Pack.
 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 3D-3 – Check ECM response.

Conditions

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

Action

  • Install Part Number 3822917 between ECM sensor port pin 2 and pin 26, as a jumper wire.
  • Read the faults.
OK NOT OK
Fault Code 123 inactive. Fault Code 122 active Fault Code 123 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 – 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 3D-4 – Check signal to return pin resistance.

Conditions

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

Action

  • Measure the resistance from pin 26 to pin 4 in the ECM sensor port;
    use test lead, Part Number 3822917.
OK NOT OK
Less than 100k ohms

  • Replace the sensor. Refer to Procedure 019-061.
 Greater than 100k ohms

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

Guided Step 4 – 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 4A – 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 4B – 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 123 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 4C – Check for a short circuit to ground.

Conditions

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

Action

  • Measure the resistance from pin 26 of the sensor harness connector to chassis ground.
  • Measure the resistance from pin 2 of the sensor harness connector to chassis ground.
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 4D – Check for a short circuit from pin to pin.

Conditions

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

Action

  • Measure the resistance from pin 2 to all other pins of the sensor harness connector.
  • Measure the resistance from pin 4 to all other pins of the sensor harness connector.
  • Measure the resistance from pin 26 to all other pins of the sensor harness 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.

 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 4E – Check for continuity in the sensor harness.

Conditions

  • Turn keyswitch OFF.
  • Disconnect the sensor harness connector from the ECM.
  • Disconnect the intake manifold pressure sensor from the sensor connector on the sensor harness.

Action

  • Measure the resistance from pin 2 of the sensor harness connector at the ECM to pin A of the sensor harness.
  • Measure the resistance from pin 26 of the sensor harness connector at the ECM to pin C of the sensor harness.
  • Measure the resistance from pin 4 of the sensor harness connector at the ECM to pin B of the sensor harness.
OK NOT OK
Less than 10 ohms Correct the pin-to-pin wiring.

Guided Step 4F – Clear and check the fault codes.

Conditions

  • Connect all the components.

Action

  • Start the engine and let it idle for one minute.
  • Snap the accelerator pedal.
  • Read the fault codes using INSITE™ electronic service tool.
OK NOT OK
Fault Code 123 inactive Fault Code 123 active

Guided Step 5 – 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.
 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 5A – Check for an 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 harness port pin 2 and pin 26.
  • Read the fault codes using INSITE™ electronic service tool .
OK NOT OK
Fault Code 123 inactive, Fault Code 122 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 – 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 5B – Check ECM signal pin resistance.

Conditions

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

Action

  • Measure the resistance from pin 26 to pin 4 in the ECM sensor port, using Part Number 3822917.
OK NOT OK
Less than 100k ohms Replace the ECM. Refer to Procedure 019-031.

Guided Step 6 – Clear the fault codes.

Guided Step 6A – Disable the fault code.

Conditions

  • Connect all the components.

Action

  • Start the engine and let it idle for 1 minute.
  • Verify that Fault Code 123 is inactive.
OK NOT OK
Fault Code 123 inactive Return to the troubleshooting steps or contact your nearest Cummins Authorized Repair Location if all the steps have been completed and checked again.

Guided Step 6B – Clear the inactive fault codes.

Conditions

  • Connect all the components.

Action

  • Erase 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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Published by Jack

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