826568 Mercury HOSE

Table 1
Diagnostic Codes Table    
Description    Conditions which Generate this Code    System Response    
273-3 Turbocharger Outlet Pressure Sensor voltage above normal     The ECM detects signal voltage that is above normal for one second.
The ECM has been powered for at least three seconds.     The code is logged.
The value of the parameter is set to zero.    
273-4 Turbocharger Outlet Pressure Sensor voltage below normal     The ECM detects signal voltage that is below normal for one second.
The ECM has been powered for three seconds.    
274-3 Atmospheric Pressure Sensor voltage above normal     The ECM detects signal voltage that is above normal for one second.
The ECM has been powered for at least three seconds.     The code is logged.
The value of the parameter is set to
45 kPa (6.5 psi).    
274-4 Atmospheric Pressure Sensor voltage below normal     The ECM detects signal voltage that is below normal for one second.
The ECM has been powered for three seconds.    System OperationUse this procedure to troubleshoot any suspect problems with the following sensors:
Atmospheric pressure sensor
Turbocharger outlet pressure sensorThe supply voltage is routed to terminal A of each sensor connector. The sensor return is routed to terminal B of each sensor connector. The sensor signal is routed to terminal C of each sensor connector. The ECM provides short circuit protection for the internal power supply. A short circuit to the battery will not damage the internal power supply.The ECM performs an automatic calibration of these sensors whenever the ECM is powered and the engine is off for at least five seconds. During an automatic calibration, the ECM calibrates pressure sensors to the value of the atmospheric pressure sensor and against an acceptable offset pressure range.The ECM continuously outputs a pull-up voltage on the input terminal from an analog sensor. The ECM uses this pull-up voltage in order to detect an open or a short in the signal circuit. When the ECM detects the presence of a voltage that is above the normal range of the sensor on the signal circuit, the ECM will generate an open circuit diagnostic code -3 for that sensor. When the ECM detects the absence of the pull-up voltage on the signal circuit, the ECM will generate a short circuit diagnostic code -4 for that sensor. The presence of pull-up voltage at the sensor connector indicates that the wires from the sensor connector to the ECM are not open or shorted to ground.
Illustration 1 g01248429
Typical schematic
Illustration 2 g01248430
P1 ECM connector (P1-2) 5 V sensor supply (P1-3) Sensor return
Illustration 3 g01248431
P2 ECM connector (P2-36) Turbocharger outlet pressure sensor (P2-37) Atmospheric sensor
Illustration 4 g01234146
Location of ECM connectors
Illustration 5 g01094844
Sensor connector (Pin A) Sensor supply (Pin B) Sensor return (Pin C) Signal
Illustration 6 g01248433
Sensor location (1) Atmospheric pressure sensor
Illustration 7 g01248432
Left side view 3606 and 3608 (2) Turbocharger compressor outlet pressure sensor
Illustration 8 g01248434
Top view 3612 and 3616 (3) Turbocharger compressor outlet pressure sensorTest Step 1. Check for "Active" or "Logged" Diagnostic Codes
Connect Caterpillar Electronic Technician (ET) to the service tool connector.
Turn the local/remote switch on the control panel to the LOCAL position.
Monitor the diagnostic codes on Cat ET. Check and record any diagnostic codes.Note: Wait at least 30 seconds in order for the diagnostic codes to become active.
Determine if a diagnostic code has occurred several times.Note: A diagnostic code that is logged several times is an indication of an intermittent problem. Most intermittent problems are the result of a bad connection between a socket and a pin in a connector or a bad connection between a wire and a terminal. The problem may be caused by moisture, corrosion, or wear.
Determine if the problem is active and related to one of the following diagnostic codes:
-3
-4Expected Result:A diagnostic code is not active.Results:
OK - A diagnostic code is not active.Repair: The problem may be intermittent. If the problem is intermittent, refer to Troubleshooting, "Inspecting Electrical Connectors".STOP
Not OK - A diagnostic code is active. Proceed to Test Step 2.Test Step 2. Check the 5 Volt Supply Voltage at the Sensor Connector
Do not disconnect the suspect connector.
Connect a voltmeter between pin A and pin B on the sensor side of the connector for the suspect sensor.
Measure the voltage between pin A and pin B for the suspect sensor(s).