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	g00834359
(1) Power indicator (2) Control indicator (3) Auto retarder indicator (4) Retarder indicator (5) Parking brake indicator (6) Accelerator pedal indicator (7) Engine speed indicator (8) Fault present indicator (9) Readout (10) Service mode indicator

Normal mode (mode 0) is the display mode for normal machine operation. When the ARC is in the normal mode, the display will show important information that is used by the service personnel. That information is listed below.

• The ARC is in proper operating condition. Whenever the key switch is turned to the ON position, the display performs a self test. Refer to Testing and Adjusting, "System Self Test". The Power Indicator (1) remains on in order to show that the power is applied to the ARC.

• A system fault had happened. The ARC continuously checks for faults in the ARC system. Faults are detected by the ARC when a signal is out of range. Detected faults are stored in memory and shown on readout (9) .

• The retarder lamp flashes in order to notify the operator or the service personnel that a fault is present. Each of the detected faults consist of two identifiers and an indicator. The identifier is displayed on readout (9). Service personnel interpret the identifiers in order to assist with troubleshooting.

The identifiers and indicators are listed below.

• The Component Identifier (CID) is a three digit code that tells the components and/or circuits that are faulty. The CID is shown on the readout (9). For example, the readout 710 appears on the display. Check the chart for 710. This code would indicate that the circuit for the supply solenoid is faulty.

• The Failure Mode Identifier (FMI) is a two digit code that tells the type of fault that happened. The two digit code is preceded by the letter F. The FMI is shown immediately after the CID on the readout (9). For example F05, check the chart. This code would indicate that the circuit is open.

• Fault present indicator (8) is red. If the indicator is ON means the fault is present and the fault is on the readout. If the indicator is OFF means the fault is not present but the faultmay have happened.

Note: When a fault is present the retarder lamp is flashing in addition to the fault present indicator (8) .

The combination of fault present indicator (8), CID, and FMI describes one detected fault.

If no faults are detected readout (9) shows "---". When a fault is detected the corresponding pair of CID and FMI appear on readout (9). The first code that appears on the readout is the CID. The CID is followed by the FMI. If more than one fault is detected each pair of CID and FMI codes scroll on readout (9). After all the faults are displayed readout (9) will read END. After a few seconds, readout (9) will start repeating the list of faults again.

Also, the ARC continuously shows the status of certain other conditions. The status indicators are active in all display modes. The seven status indicators are listed below. Also accompanying the list is a brief description of the indicators.

(1) The power indicator (1) is green. If the indicator is on that means the ARC is receiving battery voltage. This is the normal operating condition. If the indicator is off this means that no battery voltage is reaching the ARC and the ARC will not function.

(2) The control indicator (2) is red. If the indicator is on or flashing means the internal circuits in the ARC are faulty and the ARC needs to be replaced. Normally, the indicator blinks briefly during the self test when the key switch is turned OFF to ON. If the indicator is off this means the internal circuits are operating properly.

(3) The auto retarder indicator (3) is amber. If the indicator is on that means the automatic retarding pressure switch is open or the automatic retarding is active. If the indicator is off the circuit is closed or the automatic retarding is not active.

(4) The retarder indicator (4) is amber. If the indicator is on this means the retarder pressure switch is closed or the circuit is grounded. This happens when the automatic retarder or the manual retarder is active. If the indicator is off means neither retarder is active.

(5) The parking brake indicator (5) is amber. The ARC receives the parking brake signal from the "EPTCll"over the data link. If the indicator is on this means the parking brake is applied. If the indicator is off means the parking brake is not applied.

(6) The accelerator pedal indicator (6) is amber. The ARC receives the accelerator signal from the electronic engine control. IF the indicator is on that means the accelerator pedal is depressed. If the indicator is off means the accelerator pedal is not depressed.

(7) The engine speed indicator (7) is green. If the engine speed indicator is on this means the ARC is receiving a signal from the engine speed sensor. This is the normal operating condition and the engine is running. If the engine speed indicator is off the engine is not running or the sensor is bad.

(10) The service mode indicator (10) is amber. This mode is on the later truck models. If the service mode indicator is on that means the ARC is not in the normal mode.