CM2150 Electronic Control System – FAULT CODE 2973

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Overview

ISB, ISC, and ISL – Intake Manifold 1 Pressure/Temperature Sensor Circuit SMALL | MEDIUM | LARGE

Circuit Description

The electronic control module (ECM) provides a 5 volt supply to the intake manifold pressure sensor on the sensor supply circuit. The ECM also provides a ground on the sensor return circuit. The intake manifold pressure sensor provides a signal to the ECM on the intake manifold pressure sensor signal circuit. This sensor signal voltage changes, based on the pressure in the intake manifold.

This diagnostic checks the value of the intake manifold pressure sensor at key-on and while the engine is running. If the value of the intake manifold pressure is not reading ambient pressure at key-on or is not changing with engine operating conditions, this fault code is logged.

Component Location

The intake manifold 1 pressure/temperature sensor is located in the air intake horn. Refer to Procedure 100-002 in Section E.

Conditions for Running the Diagnostics

This diagnostic runs continuously when the keyswitch is in the ON position and when the engine is running.

Conditions for Setting the Fault Codes

The ECM detects that the intake manifold pressure signal reading is not changing with engine operating conditions or is reading an erratic value at key ON.

Action Taken When the Fault Code is Active

• The ECM illuminates the amber CHECK ENGINE light immediately when the diagnostic runs and fails.
• A default value for the intake manifold pressure reading is used.

Conditions for Clearing the Fault Code

The ECM will turn off the amber CHECK ENGINE light immediately after the diagnostic runs and passes.

Shop Talk

Verify the electronic control module (ECM) calibration is correct. Check the calibration revision history found on QuickServe™ Online for applicable fixes to the calibration stored in the ECM. If necessary, calibrate the ECM. Use the corresponding Troubleshooting and Repair Manual for the engine being serviced.Refer to Procedure 019-032 in Section 19.

The intake manifold 1 pressure sensor monitors pressure in the intake manifold. This fault is set active when the intake manifold pressure is too high or low for the present engine operating conditions. The ECM compares the intake manifold pressure reading to turbocharger speed to determine if the pressure reading is valid.

Possible causes of this fault are:

• A damaged intake manifold pressure sensor
• A malfunctioning barometric pressure sensor
• Leaks in the air intake system between the turbocharger and intake manifold
• Restriction in the charge-air cooler
• A malfunctioning turbocharger speed sensor
• Plugged or restricted exhaust system
• A plugged intake manifold pressure sensor
• Air filter restriction.

Refer to Troubleshooting Fault Code t05-2973