C-18 Truck Engines Caterpillar

Diagnostic Flash Code Retrieval

Usage:

C-18 MDP

"Diagnostic" Lamp

Use the "DIAGNOSTIC" Lamp or a Caterpillar electronic service tool to determine the diagnostic flash code.

Use the following procedure to retrieve the diagnostic codes if the engine is equipped with a "DIAGNOSTIC" lamp:

Turn the cruise control ON/OFF switch to the OFF position.
Move the SET/RESUME switch to either position. Hold that position until the "YELLOW" lamp begins to flash.

The "YELLOW" lamp will flash in order to indicate a two digit flash code and the SET/RESUME switch may be released. The sequence of flashes represents the system diagnostic message. Count the first sequence of flashes in order to determine the first digit of the diagnostic code. After a two second pause, the second sequence of flashes will identify the second digit of the diagnostic code.

Any additional diagnostic codes will follow after a pause. The additional diagnostic codes will be displayed in the same manner. Flash Code 55 signals that No Detected Faults have occurred since the ignition key switch has been turned to the ON position.

Refer to the Service Manual or consult an authorized Caterpillar dealer for the following items.

Further information
Assistance for repairs
Troubleshooting

The electronic diagnostic codes are listed and described in Table 1.

Note: Table 1 indicates the potential effect on engine performance with "ACTIVE" flash codes.

Some codes record events or some codes indicate that a mechanical system needs attention rather than indicating a performance problem. Troubleshooting is not required for codes "35", "41", "47" and "55". Code "01" will not flash. Some codes will limit the operation or the performance of the engine.

Table 1 indicates the potential effect on the engine performance with active flash codes. Table 1 also forms a list of Electronic diagnostic codes and descriptions.

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Table 1
	Diagnostic Flash Codes
Diagnostic Flash Code		Effect On Engine Performance⁽¹⁾				Suggested Action of the Operator
Diagnostic Flash Code		Engine Misfire	Low Power	Reduced Engine Speed	Engine Shutdown	Shut Down the Engine⁽²⁾	Service⁽³⁾	Schedule Service ASAP⁽⁴⁾
01	Idle Shutdown Override
12	Coolant Level Sensor Fault⁽⁵⁾							X
13	Fuel Temperature Sensor Fault							X
14	Retarder Solenoid Fault							X
21	Sensor Supply Voltage Fault⁽⁵⁾⁽⁶⁾		X					X
24	Oil Pressure Sensor Fault⁽⁵⁾							X
25	Boost Pressure Sensor Fault⁽⁶⁾		X					X
26	Atmospheric Pressure Sensor Fault⁽⁶⁾							X
27	Coolant Temperature Sensor Fault⁽⁵⁾⁽⁶⁾							X
28	Check Throttle Sensor Adjustment							X
29	PTO Throttle Position Sensor Fault			X			X
31	Loss of Vehicle Speed Signal			X				X
32	Throttle Position Sensor Fault			X			X
34	Engine RPM Signal Fault	X		X	X		X
35	Engine Overspeed Warning			X
36	Vehicle Speed Signal Fault			X				X
38	Inlet Air Temperature Sensor Fault⁽⁵⁾⁽⁶⁾							X
41	Vehicle Overspeed Warning			X
42	Check Sensor Calibrations		X					X
46	Low Oil Pressure Warning		X	X	X	X	X
47	Idle or PTO Shutdown Occurrence				X
51	Intermittent Battery Power to ECM	X	X		X		X
55	No Detected Faults
56	Check Customer or System Parameters		X	X				X
58	Powertrain Data Link Fault							X
59	Incorrect Engine Software							X
61	High Coolant Temperature Warning		X		X		X
62	Low Coolant Level Warning		X		X		X
64	High Inlet Air Temperature							X
65	High Fuel Temperature Warning		X					X
66	Multifunction No. 6 Output Fault							X
67	Multifunction No. 7 Output Fault							X
68	Transmission Not Responding							X
71	Ignition Key Switch Fault				X		X
72	Cylinder 1 or Cylinder 2 Fault	X	X				X
73	Cylinder 3 or Cylinder 4 Fault	X	X				X
74	Cylinder 5 or Cylinder 6 Fault	X	X				X

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⁽¹⁾	An "X" indicates that the effect on engine performance may occur, if the code is active. This depends on the exact failure.
⁽²⁾	Shut Down the Engine: Operate the engine cautiously. Get immediate service. Severe engine damage may result.
⁽³⁾	Service: The operator should go to the nearest qualified service facility.
⁽⁴⁾	Schedule Service: When it is convenient for the operator, the problem should be investigated.
⁽⁵⁾	When the diagnostic flash code is active, the effectiveness of the Engine Monitoring feature is reduced.
⁽⁶⁾	The system may be affected by these Diagnostic Flash Codes, only under specific environmental conditions. This includes engine start-up at cold temperature, cold weather operation at high altitudes, etc.