The CPC can calculate vehicle speed providing that it is properly programmed and interfaced with a Vehicle Speed Sensor (VSS) that meets requirements. The VSS (see Figure “Vehicle Speed Sensor” ) provides a vehicle speed signal for use in Cruise Control and Vehicle Speed Limiting. The VSS signal type can be changed v
Note: DDC does not approve of the use of signal generator sensors.
Figure 9. Vehicle Speed Sensor
To obtain accurate vehicle mileage, the parameters listed in Table “Vehicle Speed Sensor Parameters” must be programmed with VEPS, DRS, or DDDL 7.0.
| Parameter Group | Parameter | Range | Default |
| 8 | Vehicle Speed Sensor | 0 = No Sensor
1 = C3 Sensor 2 = Square Wave (Hall Sensor) 3 = J1939 (ECT1) 4 = Magnetic Pickup 5 = J1939 (TCO1) 6 = J1939 (CCVS Source 1) 7 = J1939 (CCVS Source 2) 8 = J1939 (CCVS Source 3) |
4 = Magnetic |
| 8 | Axle Ratio | 1 – 20.0 | 5.29 |
| 8 | Number of Output Shaft Teeth | 0 – 250 | 16 |
| 8 | Tire Revs per Unit Distance | 160 – 1599 | 312 |
| 8 | Top Gear Ratio | 0.1 – 2.55 | 1 |
| 8 | Second Highest Gear Ratio | 0.1 – 5.75 | 2.54 |
| 8 | Two Spd Axle Second Axle Ratio | 1 – 20.0 | 5.29 |
| 8 | Anti Tamper | 0 = Disable
1 = Enable VSS Anti Tamper Function via ABS 2 = Enable Anti Tamper Function via Gear Ration |
0 = Disable |
Magnetic Pickup
The magnetic pickup requirements are listed in Table “Magnetic Pickup Vehicle Speed Sensor Requirements” . Magnetic Pickup size is determined by installation requirements.
| Parameters | Range |
| Frequency Range | 0 – 10 kHz |
| Low Threshold Voltage | >1.8 Volts Peak to Peak |
The Vehicle Speed Sensor is wired to the 21–pin #3 connector of the CPC as listed in Table “Vehicle Speed Sensor Wiring” .
| CPC Connector/Pin | Function |
| 3/13 | VSS (+) |
| 3/14 | VSS (-) |
See Figure “Magnetic Vehicle Speed Sensor Installation – CPC” for the installation of the Magnetic VSS.
| Label | CPC Connector #3, 21–pin Cavity (1) | Wire Color | Vehicle Speed Sensor Connector Cavity |
| Vehicle Speed Sensor (+) | 3/13 | LT BLU/ORN | Signal |
| Vehicle Speed Sensor (-) | 3/14 | LT BLU/BLK | Return |
Figure 10. Magnetic Vehicle Speed Sensor Installation – CPC
SAE J1939 Data Link
A VSS wired to the CPC is not required if the transmission output shaft speed message is being transmitted over the SAE J1939 Data Link. To obtain accurate vehicle mileage, the parameters listed in Table “Vehicle Speed Sensor Parameters for Transmission Output Shaft Speed” must be programmed with VEPS.
| Parameter Group | Parameter | Range | Default | |
| 8 | Vehicle Speed Sensor | 0 = No Sensor
1 = C3 Sensor 2 = Square Wave (Hall Sensor) 3 = J1939 (ECT1) 4 = Magnetic Pickup 5 = J1939 (TCO1) 6 = J1939 (CCVS Source 1) 7 = J1939 (CCVS Source 2) 8 = J1939 (CCVS Source 3) |
4 = Magnetic | |
| 8 | Axle Ratio | 1 – 20.0 | 5.29 | |
| 8 | Tire Revs per Unit Distance | 160 – 1599 | 312 | |
| 8 | Top Gear Ratio | 0.1 – 2.55 | 1 | |
| 8 | Second Highest Gear Ratio | 0 — 5.75 | 2.54 | |
| 8 | Two Spd Axle Second Axle Ratio | 1 – 20.0 | 5.29 | |
| 8 | Anti Tamper | 0 = Disable
1 = Enable VSS ABS Anti Tampering Function 2 = Enable VSS without ABS Anti Tampering Function |
0 = Disable | |
VSS Anti-tamper
If the sensor appears to be working improperly, but the vehicle speed is not zero, VSS Anti-Tamper will log a VSS fault.
