3862865 Volvo.Penta Engine control unit

Table 1
Diagnostic Codes Table
CDL Code Code Description Comments
2533-5 Compression Brake Low/High Solenoid #1 current below normal 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
2534-5 Compression Brake Low/High Solenoid #2 current below normal
2534-6 Compression Brake Low/High Solenoid #2 current above normal
2535-5 Compression Brake Medium/High Solenoid #1 current below normal
2535-6 Compression Brake Medium/High Solenoid #1 current above normal
2536-5 Compression Brake Medium/High Solenoid #2 current below normal
2536-6 Compression Brake Medium/High Solenoid #2 current above normal
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" in order for this function to operate.The auto mode is selected when the engine retarder switch is in the released position. In auto mode, the retarder will be activated only when the engine speed is above 2100 rpm. The retarder will remain on until the engine speed falls below 1750 rpm.The manual mode is selected when the engine retarder switch is actuated continuously by the operator. In the manual mode, the engine retarder will be activated only when the engine speed is above 1500 rpm. The retarder will remain on until the engine speed falls below 1400 rpm, or the engine retarder switch is released.When the compression brake is activated, the engine's Electronic Control Module (ECM) disengages the throttle lock, the fuel injection, and the ether control.While compression brake operation is directly controlled by the engine ECM, the transmission ECM provides an interlock control for protection of the transmission and of the drive train. This interlock control ensures that the operating conditions for the engine, the transmission, and the machine are favorable prior to enabling the compression brakes. Once the conditions are met, the transmission ECM communicates a favorable status of the interlock control over the Cat Data Link to the engine ECM. The engine ECM then has direct control over the operation of the compression brakes. A problem with communications between the engine ECM and the transmission control will affect operation of the compression brake. The transmission control will restrict operation to the automatic mode during an active fault for the compression brake switch.Note: If a problem is suspected with the compression brake switch, refer to Troubleshooting, "Switch Circuits - Test" for troubleshooting information.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 Override"The "Compression Brake Low/High Override" and the "Compression Brake Med/High Override" are diagnostic overrides that are available in Caterpillar Electronic Technician (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 g02122717
Schematic for the compression brake circuit
Illustration 3 g02124154
Locations of the connectors that are associated with the engine's 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's 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 g02124376
Terminal locations at the P1 ECM connector for the compression brake solenoids
(Terminal 5) Digital return
(Terminal 44) Compression brake switch (NC)
(Terminal 49) Compression brake switch (NO)
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)
(P2-45) Compression brake solenoid med/high (right bank)
(P2-14) Digital return