0317174 JOHNSON BUSHING, Choke lever

Table 1
Diagnostic Codes Table
CDL Code and Description Conditions that Generate the Code System Response
2533-5 Compression Brake Low/High Solenoid #1 current below normal The Electronic Control Module (ECM) has detected an open or a short to +Battery in the signal circuit for the compression brake. The code is logged.
The operation of the compression brake is restricted to the automatic mode.
2533-6 Compression Brake Low/High Solenoid #1 current above normal The ECM has detected a short circuit in the signal circuit for the compression brake.
2534-5 Compression Brake Low/High Solenoid #2 current below normal The ECM has detected an open or a short to +Battery in the signal circuit for the compression brake.
2534-6 Compression Brake Low/High Solenoid #2 current above normal The ECM has detected a short circuit in the signal circuit for the compression brake.
2535-5 Compression Brake Medium/High Solenoid #1 current below normal The ECM has detected an open or a short to +Battery in the signal circuit for the compression brake.
2535-6 Compression Brake Medium/High Solenoid #1 current above normal The ECM has detected a short circuit in the signal circuit for the compression brake.
2536-5 Compression Brake Medium/High Solenoid #2 current below normal The ECM has detected an open or a short to +Battery in the signal circuit for the compression brake.
2536-6 Compression Brake Medium/High Solenoid #2 current above normal The ECM has detected a short circuit in the signal circuit for the compression brake.
Illustration 1 g01199118
Location of the compression brake solenoid (typical example)
The compression brake uses the engine in order to provide auxiliary braking for the machine. The compression brake reduces wear of the wheel brake components, brake oil temperature, and the chance for engine overspeed. The compression brake also aids in the controllability of the machine.If the engine is equipped with engine compression brakes, the "Engine Retarder Enable Command" parameter must be set to "Enabled".Note: A switch input to the brake ECM sets the status of the compression brake. The status is off or automatic. Software for the brake ECM controls the level of braking. The levels of braking are low and medium. The brake ECM requests the engine ECM to actuate the compression brake solenoids. The request is sent over the Cat Data Link.Perform this procedure under conditions that are identical to the conditions that exist when the problem occurs. Typically, problems with the compression brake solenoids occur when the engine is warmed up and/or when the engine is under vibration (heavy loads)."Compression Brake Solenoid Test"The "Compression Brake Solenoid Test" is a diagnostic test that is available on Caterpillar Electronic Technician (ET). Use the "Compression Brake Solenoid Test" to assist in troubleshooting problems in the circuit for the compression brake. The engine ECM will only detect shorts in the circuit for the compression brake when the test is active. "Current high" diagnostic codes (short circuits) will be logged once the test has been deactivated. The ECM will only detect opens in the circuit for the compression brake when the test is not active. The test must be activated and then deactivated before the ECM will detect an open circuit. "Current low" diagnostic codes (open circuits) will be active once the test has been deactivated.Note: The engine speed must be zero before the "Compression Brake Solenoid Test" will function."Compression Brake Solenoid Override"The "Compression Brake Low/High Override" and the "Compression Brake Med/High Override" are diagnostic overrides that are available in Cat ET. Use the overrides to assist in troubleshooting problems in the circuit for the compression brake. The ECM will only detect shorts in the circuit for the compression brake solenoid when the overrides are active. The overrides must be activated and then deactivated before the ECM will detect an open circuit.Note: The engine speed must be zero before the overrides will function.Note: All of the retarder solenoids share a single return circuit. A short circuit or an open circuit in the return wire for the retarder solenoids will cause a problem with all of the solenoids.
Illustration 2 g02149672
Schematic for the compression brake circuit
Illustration 3 g02124154
Locations of the connectors that are associated with the engine compression brakes (top side engine view)
(1) J1/P1 ECM connectors
(2) J2/P2 ECM connectors
(3) Connectors at the valve cover that are for the compression brakes for the right bank of cylinders
(4) Connectors at the valve cover that are for the compression brakes for the left bank of cylinders Test Step 1. Inspect the Electrical Connectors and the Wiring
Electrical shock hazard. The electronic unit injector system uses 90-120 volts.
Remove electrical power from the engine ECM. A strong electrical shock hazard is present if the electrical power is not removed from the engine ECM.
Thoroughly inspect connectors (1), (2), (3), and (4). Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
Illustration 4 g02149705
Terminal locations at the P1 connector for engine ECM
(Terminal 8) Cat Data Link+
(Terminal 9) Cat Data Link−
Illustration 5 g02124414
Terminal locations at the P2 connector for the compression brake solenoids
(P2-1) Compression brake solenoid low/high (left bank)
(P2-5) Compression brake solenoid low/high (right bank)
(P2-8) Compression brake solenoid med/high (left bank)
(P2-14) Digital return
(P2-45) Compression brake solenoid med/high (right bank)