CUP 3A4521 - Caterpillar

Use the instrument cluster or use the Caterpillar Electronic Technician (Cat ET) to determine the diagnostic codes for the Transmission ECU. After determining the diagnostic codes, refer to the corresponding test procedure for more information. Perform the procedure that corresponds with the correct diagnostic code. The following table is a list of possible diagnostic codes for the ECU.
Table 1
Diagnostic Trouble Codes For Transmission ECM (MID 81)
DTC Description Test Procedure
120-1 Torque Conv Oil Temp Sensor Data Valid But Below Normal Operational Range Sensor Signal (Analog, Passive) - Test
120-3 Torque Conv Oil Temp Sensor Voltage Above Normal Sensor Signal (Analog, Passive) - Test
120-4 Torque Conv Oil Temp Voltage Below Normal Sensor Signal (Analog, Passive) - Test
124-1 Transmission Oil Level – Data Valid But Below Normal Operational Range Sensor Signal (Analog, Passive) - Test
124-3 Transmission Oil Level - Voltage Above Normal Sensor Signal (Analog, Passive) - Test
124-4 Transmission Oil Level - Voltage Below Normal Sensor Signal (Analog, Passive) - Test
126-16 Transmission Oil Filter Plugged
127-3 Transmission Oil Pressure: Voltage Above Normal Sensor Signal (PWM) - Test
127-4 Transmission Oil Pressure: Voltage Below Normal Sensor Signal (PWM) - Test
161-2 Torque Conv. Output Speed Sensor Erratic Speed Sensor - Test
161-8 Torque Conv. Output Speed Sensor Abnormal PW, Freq, Period Speed Sensor - Test
168-1 Electrical System Voltage Low Electrical Power Supply - Test
177-3 Trans Oil Temp Sensor Voltage Above Normal Sensor Signal (Analog, Passive) - Test
177-4 Trans Oil Temp Sensor Voltage Below Normal Sensor Signal (Analog, Passive) - Test
190-2 Engine Speed Sensor Erratic Speed Sensor - Test
190-4 Engine Speed Sensor: Voltage Below Normal Speed Sensor - Test
190-8 Engine Speed Sensor Abnormal Signal Speed Sensor - Test
191-2 Transmission Output Shaft Speed: Erratic, Intermittent, or Incorrect Speed Sensor - Test
191-4 Transmission Output Shaft Speed: Voltage Below Normal Speed Sensor - Test
191-8 Transmission Output Shaft Speed: Abnormal Frequency, Pulse Width, or Period Speed Sensor - Test
524-9 Shifter Selector Abnormal Update Rate Sensor Signal (PWM) - Test
524-14 Shifter Selector Erratic Sensor Signal (PWM) - Test
525-2 Trans Gear Lever Sel. Sensor Erratic, Intermittent, Incorrect Sensor Signal (PWM) - Test
525-9 Transmission Requested Gear: Abnormal Update Rate (Shifter Lost) Cat Data Link - Test
639-9 J1939 Network #1: Abnormal Update Rate (No CAN Communication) Cat Data Link - Test
639-14 J1939 Network #1: Special Instruction (Engine is not on the CAN Network) Cat Data Link - Test
678-3 8V Sensor Power Supply Voltage Above Normal Electrical Power Supply - Test
678-4 8V Sensor Power Supply Voltage Below Normal Electrical Power Supply - Test
682-2 Lockup Disable Switch Incorrect Switch Circuits - Test
734-3 Transmission Solenoid Clutch #1 Voltage Above Normal Solenoid Valve - Test
734-5 Transmission Solenoid Clutch #1 Current Below Normal Solenoid Valve - Test
734-6 Transmission Solenoid Clutch #1 Current Above Normal Solenoid Valve - Test
734-11 Transmission Solenoid Clutch #1 Other Failure Mode