SPOOL 1P9685 - Caterpillar

System Operation Description:Use this procedure to troubleshoot the electrical system if a problem is suspected with one of the supply circuits. Also, use this procedure if any one of the diagnostic codes in Table 1 is active or easily repeated.
Table 1
Diagnostic Codes Table
Code and Description Conditions which Generate this Code System Response
3509-3 Sensor Supply Voltage 1 : Voltage Above Normal The Electronic Control Module (ECM) detects a voltage for the 5 V power supply that is above 5.2 V for one second. The code is logged.
The amber warning lamp is illuminated.
The ECM will use the last good value for each parameter that uses the 5 V supply.
The service tool displays "Data Error" on the status screen for all of the 8 V sensors and the sensor supply.
3509-4 Sensor Supply Voltage 1 : Voltage Below Normal The ECM detects a voltage for the 5 V power supply that is below 4.8 V for one second. The code is logged.
The amber warning lamp is illuminated.
The ECM will use the last good value for each parameter that uses the 5 V supply.
The service tool displays "Data Error" on the status screen for all of the 8 V sensors and the sensor supply.
The ECM retries the circuit at two second intervals in order to recheck the circuit.
3511-6 Sensor Supply Voltage 3 : Current Above Normal While the output driver for the oxygen sensors is on, the ECM detects a high current in the circuit for two seconds. The code is logged.
The amber warning lamp is illuminated.
The activation of this code is latched by the ECM. The power to the ECM must be powered in order to reset the power supply. 24 V Power SupplyThe ECM supplies 24 VDC to the voltage converter for the oxygen sensors through terminal location P1-28 at the ECM.The 3511-6 becomes activated if a short to ground is detected in the harness between the ECM and the voltage converter.8 V Power SupplyThe ECM supplies 8 VDC to the speed/timing sensor.For information that is related to troubleshooting the circuit for the speed/timing sensor, refer to Troubleshooting, "Speed/Timing - Test" for details.5 V Power SupplyThe ECM supplies 5.0 0.2 VDC to the following sensors:
Engine oil pressure sensor
Intake manifold pressure sensor
Temperature sensor at the inlet of the catalytic converter
Temperature sensor at the outlet of the catalytic converterThe ECM also provides 5.0 0.2 VDC to the speed control potentiometer.There are five outputs at the ECM for the 5 V sensor supply:
J1-41
J1-42
J2-46
J2-48The internal circuitry for the outputs is wired to the same voltage source inside the ECM. A short circuit on one of these terminals will cause a short circuit on the other terminal. A 3509-4 Sensor Supply Voltage 1 : Voltage Below Normal will be activated if the following conditions occur:
The desired speed signal wire is shorted to ground.
The speed control potentiometer is near the maximum desired speed or at the maximum desired speed.A diagnostic code for the 5 V power supply is probably caused by a short circuit or