BLADE AS-WIPER 2926567 - Caterpillar

System Operation Description:Use this procedure under the following situation:
Active diagnostic code
Easily repeated diagnostic code that is associated with the vehicle speed circuitRefer to Troubleshooting, "Vehicle Speed Circuit - Calibrate" if the vehicle speed is being calibrated in PPM (pulses per mile) or PPKM (pulses per kilometer).The following background information is related to this procedure:The vehicle speed circuit consists of the vehicle speed source and associated wiring. The vehicle speed source is installed by the vehicle OEM. Usually, a sensor reads movement of the transmission output shaft from the teeth on a chopper wheel. The ECM converts the signal from the vehicle speed source into vehicle speed for the following functions:
Cruise control
Idle speed control
Progressive shift
Speedometer
PTO operation
Vehicle speed limiting
Engine retarder
Idle shutdown
Trip data
Maintenance dataTo begin troubleshooting a vehicle speed problem, the following information must be determined:The problem is electrical or the problem is a calibration problem.Electrical problems are indicated by an erratic speed signal or by no speed signal. A calibration problem is indicated by a stable ECM speed, but an inaccurate ECM speed. Another indication of a calibration problem is a stable speedometer speed that is inaccurate.If the problem is related to vehicle speed calibration, refer to Troubleshooting, "Vehicle Speed Circuit - Calibrate" for calibrating the vehicle speed in PPKM (pulses per kilometer) or PPM (pulses per mile). The ECM speedometer output signal is set to 18,600 PPKM (30,000 ppm) and the ECM speedometer output signal cannot be changed. All speedometers that are driven by the ECM output (J1/P1-10 & 16) must match the ECM (30,000 ppm) in order to operate properly.The type of vehicle speed sensor that is installed on the vehicle must be determined.Both single coil magnetic sensors and dual coil magnetic sensors are commonly used. Caterpillar recommends single coil magnetic sensors. Some of the vehicles may provide the vehicle speed through the transmission ECM.You must determine if the vehicle speedometer is driven from the ECM.The ECM can drive the speedometer through the connection to J1-10 (speedometer-) and/or J1-16 (speedometer+). Note: The ECM may also drive the speedometer by a connection to the J1587 ATA data link or to the J1939 data link, if the instrument cluster is capable of interpreting the signal.Vehicle Speed Circuit WiringThe vehicle speed signal is connected to the ECM at J1/P1-12 (vehicle speed in -) and J1/P1-18 (vehicle speed in +). Speedometer ConnectionIf the speedometer is driven by the ECM output, the speedometer is connected to the following terminals:
J1/P1-10 (Speedometer-)
J1/P1-16 (Speedometer+)Note: Some speedometers require only one of the ECM signal lines to operate. Other speedometers may require both of the ECM signal lines to operate.Speedometer Special Test If the vehicle speedometer is driven by ECM output, the speedometer circuit can be checked by using the electronic service tool. The "55 mph VSP/Speedometer Test" will drive the speedometer to approximately 55 mph under the following conditions:
The "55 mph VSP/Speedometer Test" is activated.
The circuit is operating properly.
The speedometer is operating properly.Note: While the test is active, the odometer will increment mileage.Magnetic SensorsA magnetic pickup will