854445 Mercury SENSOR, MAP

Table 1
Diagnostic Codes Table    
Code and Description     Conditions which Generate this Code     System Response    
41-3 8 Volt DC Supply voltage above normal     The digital sensor supply voltage is above normal for one second.     The code is logged.
All sensors are set to default values.    
41-4 8 Volt DC Supply voltage below normal     The digital sensor supply voltage is below normal for one second.    
262-3 5 Volt Sensor DC Power Supply voltage above normal     The analog sensor supply voltage is above normal for one second.     The code is logged.
All sensors are set to default values.    
262-4 5 Volt Sensor DC Power Supply voltage below normal     The analog sensor supply voltage is below normal for one second.    System OperationThe ECM supplies a regulated voltage of 5.0 0.2 VDC to the following sensors:
Atmospheric pressure sensor
Engine oil pressure sensor
Fan pump pressure sensor
Fuel pressure sensor
Intake manifold pressure sensor
RH Intake manifold pressure sensor
Turbocharger inlet pressure sensorThe ECM supplies a regulated voltage of 8.0 0.4 VDC to the decelerator pedal position sensor.The supply voltage for the sensors is routed from the ECM to terminal A of each sensor connector. The sensor return for the sensors is routed from the ECM to terminal B 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.Note: The sensors are not protected from overvoltage. A short from the supply line to the +Battery may damage the sensors. If any of the -3 diagnostic codes are active, it is possible that a sensor has been damaged. Repair the sensor supply and check for any active sensor diagnostic codes in order to determine if a sensor has failed.
Illustration 1 g01418680
Typical schematic
Illustration 2 g01418681
P1 ECM connector (P1-2) 5 V Sensor supply (P1-3) Analog sensor return (P1-4) 8 V Sensor supply (P1-5) Digital sensor return
Illustration 3 g01418683
P2 ECM connector (P2-17) Sensor return (P2-72) 5 V Sensor supply
Illustration 4 g01159881
Sensor connector (A) 5 V or 8 V sensor supply (B) Sensor return (C) Signal
Illustration 5 g01415758
Location of ECM connectorsTest Step 1. Inspect the Electrical Connectors and the Wiring
Turn the keyswitch to the OFF position.
Thoroughly inspect the J1/P1 ECM connector and the J2/P2 ECM connector. Inspect all of the connectors that are associated with the circuit.Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
Perform a 45 N (10 lb) pull test on each of the wires in the ECM connectors that are associated with the circuit.
Check the ECM connector (allen head screw) for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
Check the harness and wiring for abrasion and for pinch points from the sensors back to the ECM.Expected Result:All connectors, pins and sockets are completely coupled and/or inserted and the harness and wiring are free of corrosion, of abrasion and of pinch points.Results:
OK - The harness and connectors appear to be OK. Proceed to Test Step 2.
Not OK - There is a problem with the connectors and/or wiring.Repair: Repair the connectors or wiring and/or replace the connectors or wiring. Ensure that all of the seals are properly in place and ensure that the connectors are completely coupled.Verify that the repair eliminates the problem.STOPTest Step 2. Check for Active Diagnostic Codes
Connect Caterpillar Electronic Technician (ET) to the service tool connector.
Turn the keyswitch to the ON position.
Monitor the active diagnostic code screen on Cat ET. Check and record any active diagnostic codes. Look for the following diagnostic codes:
41-3
41-4
262-3
262-4 Note: Wait at least 30 seconds in order for the diagnostic codes to become active.Expected Result:No diagnostic codes are active.Results:
OK - No diagnostic code is active.Repair: The problem is no longer present. If the problem is intermittent, refer to Troubleshooting, "Electrical Connectors - Inspect".STOP
Not OK - A 262-3, or 262-4 diagnostic code is active at this time. Proceed to Test Step 3.
Not OK - A 41-3 or 41-4 diagnostic code is active at this time. Proceed to Test Step 5.Test Step 3. Disconnect the 5 Volt Sensor(s) while you Monitor the Active Diagnostic Codes
Monitor the active diagnostic code screen on Cat ET while you disconnect each 5 Volt sensor at the sensor connector. Check for an active 262-3 code or an active 262-4 code.Note: Wait at least 30 seconds in order for the diagnostic codes to become active.
Disconnect the following sensors one at a time:
Atmospheric pressure sensor
Engine oil pressure sensor
Fan pump pressure sensor
Fuel pressure sensor
Intake manifold pressure sensor
RH Intake manifold pressure sensor
Turbocharger inlet pressure sensor
Turn the keyswitch to the OFF position.Expected Result:The diagnostic code deactivates when a particular sensor is disconnected.Results:
OK - The diagnostic code deactivates when a particular sensor is disconnected.Repair: Connect the suspect sensor. If the code returns, replace the sensor. Connect the connector(s). Verify that the problem is resolved.STOP
Not OK - The diagnostic code remains active after the sensor(s) is disconnected. Leave the sensor(s) disconnected. The sensor(s) is not the cause of the diagnostic code. Proceed to Test Step 4.Test Step 4. Check the 5 Volt Supply Voltages at the ECM
Disconnect the J2/P2 ECM connector.
Fabricate two jumper wires that are long enough to be used to measure the supply voltages at the ECM connector. Crimp connector sockets to one end of each jumper wire.
Remove the wires from terminal locations P2-72 (5 V sensor supply) and P2-17 (sensor return). Install a jumper wire into each of these terminal locations.