825050 Mercury PLATE

Table 1
CDL Code and Description
100-3 Engine Oil Pressure Sensor : Voltage Above Normal
100-4 Engine Oil Pressure Sensor : Voltage Below Normal
110-3 Engine Coolant Temperature Sensor : Voltage Above Normal
110-4 Engine Coolant Temperature Sensor : Voltage Below Normal
172-3 Intake Manifold Air Temperature Sensor : Voltage Above Normal
172-4 Intake Manifold Air Temperature Sensor : Voltage Below Normal
175-3 Engine Oil Temperature Sensor : Voltage Above Normal
175-4 Engine Oil Temperature Sensor : Voltage Below Normal
542-3 Engine Oil Pressure Sensor - Before Oil Filter : Voltage Above Normal
542-4 Engine Oil Pressure Sensor - Before Oil Filter : Voltage Below Normal Note: The engine coolant temperature sensor is a 2-wire passive sensor. The Electronic Control Module (ECM) applies a voltage to the signal wire of the sensor. As the temperature of the sensing element changes, the resistance of the sensor circuitry changes proportionally. The ECM detects a voltage drop across the resistance of the sensor and equates the voltage drop to the temperature measurement of the sensor. The sensor does not require a separate supply voltage from the ECM. Background InformationFor analog sensors, the ECM continuously creates a pull-up voltage on the signal wire for each sensor. The ECM uses this pull-up voltage in order to detect a problem in the signal circuit. When the ECM detects voltage that is above a threshold on the signal wire, the ECM activates a -3 diagnostic code. When the ECM detects voltage that is below a threshold on the signal wire, the ECM activates a -4 diagnostic code.Note: Wait at least 30 seconds in order for the ECM to detect the diagnostic code.A -3 code is probably caused by a problem in an engine harness. There may be an open circuit in a harness, or a short circuit to a positive voltage source in a harness. The next likely cause is a sensor problem. The least likely cause is a problem with the ECM.A -4 code is probably caused by a short circuit to ground in an engine harness. The next likely cause is a sensor problem. The least likely cause is a problem with the ECM.This troubleshooting procedure may generate additional diagnostic codes. Ensure that you continue to troubleshoot the original diagnostic code. Clear the diagnostic code after the problem is resolved.
Illustration 1 g02334898
Schematic for the analog sensors
Test Step 1. Inspect the Electrical Connectors and the Wiring
Set the engine control to the OFF/RESET mode.
Illustration 2 g01252046
Location of the analog sensors (left front engine view)
(1) Inlet air temperature sensor
(2) Engine coolant temperature sensor
(3) Pressure sensor for unfiltered oil
(4) Pressure sensor for filtered oil
(5) Oil temperature sensor
Illustration 3 g01395887
Location of the ECM connectors that are for the analog sensors
(6) P1 ECM connector Note: For the following steps, refer to Troubleshooting, "Inspecting Electrical Connectors".
Thoroughly inspect the connectors for sensors (1), (2), (3), (4), and (5). Also, thoroughly inspect ECM connectors (6).
Check the allen head screw for each of the ECM connectors for the proper torque. Refer to Troubleshooting, "Inspecting Electrical Connectors" for the correct torque value.
Illustration 4 g02334880
P1 ECM connector
(P1-14) Inlet air temperature
(P1-17) Engine oil temperature
(P1-24) Filtered engine oil pressure
(P1-26) Unfiltered engine oil pressure
(P1-27) Engine coolant temperature
Illustration 5 g01155187
Locations of the terminals for the 2-pin connector
Illustration 6 g01159881
Locations of the terminals for the 3-pin connector
Perform a 45 N (10 lb) pull test on each of the wires that are associated with the circuits for the analog sensors.
Check the harnesses and wiring for abrasion and for pinch points from each 5 V sensor to the ECM. Expected Result:All of the connectors, pins, and sockets are connected properly. The connectors and the wiring do not have corrosion, abrasion, or pinch points.Results:
OK - All of the connectors, pins, and sockets are connected properly. The connectors and the wiring do not have corrosion, abrasion, or pinch points. The components are in good condition with proper connections. Proceed to Test Step 2.
Not OK - At least one of the connectors, pins, and/or sockets are not connected properly. At least one of the connectors and/or the wiring have corrosion, abrasion, and/or pinch points.Repair: Perform the necessary repairs and/or replace parts, if necessary.STOPTest Step 2. Check for Diagnostic Codes Related to the Sensor Supply
Establish communication between Caterpillar Electronic Technician (ET) and the engine ECM. Refer to Troubleshooting, "Electronic Service Tools", if necessary.
Set the engine control to the STOP mode.
Observe the "Active Diagnostic" screen on Cat ET. Allow 30 seconds for any codes to activate. Look for these codes for the sensor supply:
262-3 5 Volt Sensor DC Power Supply : Voltage Above Normal
262-4 5 Volt Sensor DC Power Supply : Voltage Below NormalExpected Result:There are no active diagnostic codes for the sensor supply.Results:
No Sensor Supply Codes Active - There are no active sensor supply diagnostic codes. Proceed to Test Step 3.
Active 262-3 or 262-4 - There is an active sensor supply diagnostic code. Do not use this procedure for a problem related to the power supply for the sensors.Repair: Refer to Troubleshooting, "+5V Sensor Voltage Supply".If necessary, return to this procedure to troubleshoot the analog sensor after the sensor supply diagnostic code has been resolved.STOPTest Step 3. Check for Active Diagnostic Codes for the Analog Sensors
Observe the "Active Diagnostic" screen on Cat ET. Wait at least 30 seconds so that any codes may become activated. Check if any of the following diagnostic codes are active:
100-3 Engine Oil Pressure Sensor : Voltage Above Normal
100-4 Engine Oil Pressure Sensor :