0322664 JOHNSON ORIFICE PLUG, (45c),85 hp

Table 1
ECM Output for the 4-Pin Sensor
Pin location Engine coolant level normal Engine coolant level low
J1-49 5 VDC 0 VDC
J1-54 0 VDC 5 VDC 2-Wire Float SensorTo use a 2-wire float sensor, the parameter "Coolant Level Sensor" must be programmed to "2-wire float sensor". The sensor is connected to P1/J1-26 (sensor input) and to P1/J1-5 (AP sensor/switch common). The sensor will provide information to the ECM at P1/J1-26 that will enable the ECM to determine if the coolant level is normal, low, or extremely low.If this parameter is set and a sensor is not installed, 111-02 diagnostic code will be logged."2-Pin Switch" (GMT-560)The "2-pin switch" is a switch that is provided by the OEM for the vehicle. The switch is also installed by the OEM. This coolant level switch is available only for the GMT-560 application.The ECM detects closed contacts for a coolant level that is present "2-pin switch" and open contacts when a coolant level is not present. Terminals J1/P1-49 and J1/P1-3 are used for the "2-pin switch".Refer to OEM information for the proper troubleshooting procedure for the "2-Pin Switch".Test Step 1. Use Caterpillar Electronic Technician (ET) to Check for an Active Coolant Level Sensor Fault
Connect Cat ET to the data link connector.
Turn the keyswitch to the ON position.
Access the active diagnostic screen on Cat ET.
Verify that a diagnostic code that is related to the coolant level switch is active. Expected Result:Result 1 111-02 diagnostic code is active. This fault indicates that a problem exists with the 4-pin sensor. Ensure that the vehicle is equipped with a 4-pin sensor.Result 2 111-03 diagnostic code or 111-04 diagnostic code is active. These faults indicate that a problem exists with the 2-wire float sensor. Ensure that the vehicle is equipped with a 2-wire float sensor.Result 3 111-01, 111-11, or 111-14 diagnostic code is active.Results:
Result 1 - Proceed to Test Step 2.
Result 2 - Proceed to Test Step 8.
Result 3 - Repair: Refer to Troubleshooting, "111-01 Low Coolant Level Warning", Troubleshooting, "111-11 Very Low Coolant Level" or Troubleshooting, "111-14 Low Coolant Level Warning" for the proper troubleshooting procedure.STOPTest Step 2. Inspect Electrical Connectors and Wiring for the 4-Pin Sensor
Illustration 1 g01118000
This is a typical schematic for the 4-pin sensor.
The return wire may be connected to P1-3, P1-5, or P1-18.
Illustration 2 g01153498
Pin locations on ECM connector
(P1-2) +5V supply
(P1-5) AP sensor/switch common
(P1-49) Coolant level normal
(P1-54) Coolant level low
Thoroughly inspect J1/P1 ECM connector, the connector for the extension harness for the coolant level and the terminals for the coolant level sensor in the connectors. The connector for the extension harness for the coolant level connects the coolant level sensor to the vehicle harness in the engine compartment of some chassis. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
Perform a 45 N (10 lb) pull test on each of the wires in the ECM connector that are associated with the following connections:
P1-2 +5V supply
P1-5 AP sensor/switch common
P1-49 Coolant level normal
P1-54 Coolant level lowRefer to Illustration 2.
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 pinch points from the sensor 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 or of pinch points.Results:
OK - Proceed to Test Step 3.
Not OK - 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. Clear all diagnostic codes.STOPTest Step 3. Disconnect the Coolant Level Sensor and Check the Supply Voltage (+5 VDC)
Turn the keyswitch to the OFF position.
Disconnect the coolant level sensor from the harness.
Use a multimeter to measure the voltage at the harness connector from terminal C (+ 5 VDC) to terminal B (AP sensor/switch common).
Turn the keyswitch to the ON position. Expected Result:The measured voltage is 5.0 0.2 VDC.Results:
OK - Proceed to Test Step 4.
Not OK - Proceed to Test Step 5.Test Step 4. Disconnect the Coolant Level Sensor and Check the Coolant Level Harness
Illustration 3 g00651005
Jumper wire