Programmable Relay Control Module (PRCM) Caterpillar

Illustration 1	g00715369
System Schematic of the PRCM, Relay Driver Module and Relay Boards

The RDM communicates with the PRCM by a serial data link. When the data link malfunctions, the "R1" output (terminal 2 of the RDM) will flash at a rate of .5 Hz. Relays "R2" through "R9" will maintain the present state or relays "R2" through "R9" will default to the OFF position. This is controlled by a jumper between terminal 6 and terminal 7 of the RDM. If the jumper is NOT present and the serial data link has a failure, relays "R2" through "R9" will remain in the present state. If the jumper is present, relays "R2" through "R9" will default to the OFF position.

Note: The maximum number of the RDM or the Customer Interface Module (CIM) that may be connected to the serial data link is equal to two. The maximum distance between a module and the PRCM is 305 m (1000 ft). The LED indicators for the RDM may start flashing if the specifications for the maximum distances are not met. The PRCM may display a CID 0334 diagnostic code. If the setup is not in compliance with the specifications, reduce the number of modules and/or shorten the distance to the modules.

Note: The following procedure can create numerous related diagnostic codes. When all harnesses are reconnected, the related diagnostic codes will be shown as being not active. Clear all related diagnostic codes after this procedure is completed.

The possible cause of a CID 0334 FMI 03 is a short to "B+" and the wire connected to contact 35 of the PRCM.

The PRCM treats a CID 0334 FMI 03 diagnostic code as an alarm. Clear the diagnostic code from the fault log after the troubleshooting procedure is completed.

Note: Check the terminal strips on the subpanel for a short when a CID 0334 FMI 03 diagnostic code is active on the upper display and no alarm module is installed. Perform the check from the signal wire to "B+". Also, check the customer connection box for a short from the alarm data signal wire to "B+".

Test Step 1. CHECK IF THE DIAGNOSTIC CODE IS ACTIVE.

1. Turn the engine control switch (ECS) to the OFF/RESET position and then turn the ECS to the STOPposition.

2. Press the "MODE" button.

   Note: The "MODE" button is accessed from the diagnostic code viewing/clearing menu.

3. Observe the upper display for a CID 0334 FMI 03. The diagnostic code is active if the upper display shows a CID 0334 FMI 03.

4. If the diagnostic code is not showing, enter the service mode and view the fault log. Check the upper display in order to verify if the diagnostic code is active.

   Note: The PRCM must be set up properly in order to view the fault log. See Systems Operation, "Setpoint Viewing and Programming".

Expected Result:

A CID 0334 FMI 03 is active.

Results:

• OK - A CID 0334 FMI 03 is active. Proceed to test step 3.

• NOT OK - A CID 0334 FMI 03 has not occurred. The diagnostic code is NOT active. The PRCM must not have been setup in order to view logged diagnostics during the initial setup.

  Repair: The initial diagnostic code was probably caused by a poor electrical connection or a short at one of the harness connectors. See Testing and Adjusting, "Electrical Connector - Inspect".

  Proceed to test step 2.

Test Step 2. CHECK FOR A SHORTED DATA LINK WIRE.

1. Disconnect the cable for the negative terminal for the battery or open the optional battery disconnect switch.

2. Disconnect both ends of the data link wire. Disconnect contact 35 of the PRCM and terminal 4 of the RDM.

3. Measure the resistance from the data link wire to the battery positive terminal of the PRCM.

Expected Result:

The resistance that is measured is greater than 5000 ohms.

Results:

• OK - The resistance that is measured is greater than 5000 ohms. Proceed to test step 3.

• NOT OK - The resistance that is measured is LESS than 5000 ohms. The data link wire has failed. The harness wiring has failed between the RDM and the PRCM.

  Repair: Repair the harness wiring or replace the harness wiring.

  Stop.

Test Step 3. CHECK THE RDM.

1. The cable for the negative terminal of the battery remains disconnected or the optional battery disconnect switch remains open.

2. At the RDM, measure the resistance from terminal 4 (positive meter lead) to the + battery.

Expected Result:

The resistance that is measured is greater than 5000 ohms.

Results:

• OK - The resistance that is measured is greater than 5000 ohms. Proceed to test step 4.

• NOT OK - The resistance that is measured is LESS than 5000 ohms.

  Repair: Replace the RDM.

  Stop.

Test Step 4. CHECK THE PRCM.

1. The data link wires remain disconnected.

2. Connect the cable on the negative terminal of the battery or close the optional disconnect switch.

3. Check the status of CID 0334 FMI 03.

Expected Result:

The diagnostic code is NOT active.

Results:

• OK - The diagnostic code is NOT active. The diagnostic code does NOT exist at this time.

  Repair: The initial diagnostic code was probably caused by a poor electrical connection or a short at one of the harness connectors that was disconnected and reconnected. Check the wiring for problems and resume normal operation. Watch for a recurrence of the problem.

  Stop.

• NOT OK - The diagnostic code has NOT been corrected. The PRCM may have failed.

  Repair: It is unlikely that the PRCM has failed. Exit this procedure and perform this procedure again. If the cause of the diagnostic code is not found, replace the PRCM. See Testing and Adjusting, "Programmable Relay Control Module - Replace".

  Stop.