5130, 5130B and 5230 Excavators, 784B, 785B, 785C, 789B, 789C, 793B and 793C Off-Highway Truck/Tractors and 992G, 994 and 994D Wheel Loaders Vital Information Management System (VIMS) Caterpillar

Identification of Sensor Wire and Contacts

Illustration 1	g00315944
Typical Schematic Symbol of a Pulse Width Modulated Sensor

Note: In addition to the “Pulse Width Modulated (PWM) Sensor - Test”, the VIMS diagnostics are helpful in troubleshooting sensors.

When you are testing a sensor, it is necessary to identify the connector contacts and the harness wires. The Electrical System Schematic shows the numbers of the connector contacts which correspond to the wire numbers. See the Electrical System Schematic in the Service Manual for the machine.

On all machines, the wire numbers and connector contacts are identified by these general rules:

• The +V wire number (power) is between 100 and 199. The +V contact corresponds to this wire number.

• The ground wire number is between 200 and 299. The ground contact corresponds to this wire number.

• The number of the signal wire is between 400 and 499. The signal contact corresponds to this wire number.

For an example, see Illustration 1:

• The +V wire is wire number 113.

• The +V contact is contact A.

• The ground wire is wire number 201.

• The ground contact is contact B.

• The signal wire is wire number 443.

• The signal contact is contact C.

Procedure

1. TROUBLESHOOT THE SENSORS.

   Troubleshoot sensor circuits in the following order.

   1. Perform the “Sensor Signal Voltage -Tests”. This test checks the sensor voltages at the sensor, when all the circuits are connected. DISCONNECT NOTHING. Troubleshoot “as is” before disconnecting any circuits. Disconnecting the sensor from the harness before measuring the voltage may alter a poor connection. This will make the proof of cause difficult or impossible.

   2. Perform the Sensor Dynamic Test, if necessary.

   3. The VIMS interface module is the cause of the fault if the sensor and the harness are correct. Replace the VIMS interface module. Refer to the Testing and Adjusting, "Module - Replace".

To identify the sensor wires and connector contacts, see 1. Otherwise, proceed to “Sensor Signal Voltage -Test”.