768C, 769C, 769D, 772B, 773B, 773D, 776C, 777B, 777D, 784B, 785, 785B, 789, 789B, 793, 793B and 793C Off-Highway Truck/Tractors and 771C, 771D and 775D Quarry Trucks Automatic Retarder Control (ARC) System Caterpillar

Illustration 1	g00348896
(A3) Control solenoid (A4) Supply solenoid (A5) Retarder lamp

Mode 3 is used to determine whether the outputs of the Automatic Retarder Control (ARC) are active or inactive. The ARC does not detect all faults. This mode is useful for tracing circuits and for determining the status of the outputs. The Electrical System Schematic is also necessary in order to properly use Mode 3.

The readout consists of numerous segments. Each output and the corresponding connector contact is assigned to a specific segment of the readout. See Illustration 1. If a segment is on, the corresponding output is being activated by the ARC. If a segment is off, the corresponding output is not being activated by the ARC. All of the segments of the readout are not used.

Note: The indicators also function in the same manner as the Normal Mode (Mode 0). See Systems Operation, "Normal Mode".

The display enters Mode 3 when "-3-" is shown on the readout and the set switch and the clear switch are released. The display exits Mode 3 when the set switch and the clear switch are depressed simultaneously or when the engine start switch is turned to the OFF position.

For more information about changing modes, see Testing and Adjusting, "Using Service Display Mode to Determine Diagnostic Codes".