Method of detecting vehicle speed sensor failure

• US 20060253236A1
• Filed: 05/04/2005
• Published: 11/09/2006
• Est. Priority Date: 05/04/2005
• Status: Active Grant

• Current Assignee: Detroit Diesel Corporation (Daimler Truck Holding AG)
• Original Assignee: Detroit Diesel Corporation (Daimler Truck Holding AG)
• Inventors: Hawkins, Jeffery Scott, Cairns, Hugh Joseph
• Granted Patent: US 7,286,917 B2
• Time in Patent Office: Days
• US Class Current: 701/34
• CPC Class Codes: G01P 21/02 of speedometers
• CPC Class Codes: G07C 5/0816 Indicating performance data, e.g. occurrence of a malfunction

Abstract

A method of detecting vehicle speed sensor failures is disclosed. The method is intended to prevent or discourage tampering with a vehicle'"'"'s speed limiting system. The method includes the steps of determining whether the transmission is in neutral or whether the transmission is in its converter mode to prevent false indications of speed sensor failure under certain circumstances.

Claims

1. A method for detecting vehicle speed sensor failure, comprising:

determining whether a vehicle speed value is below a maximum threshold speed value;

determining whether a fueling rate value is above a minimum threshold fueling value;

determining whether an engine speed value is above a minimum threshold rpm value;

determining whether the vehicle transmission is in neutral; and

logging a fault code.

2. The method of claim 1 further comprising verifying the status of each determining step at least twice prior to logging the fault code.

3. The method of claim 2 wherein the step of verifying the determining steps includes incrementing a counter the first time that all of the determining step conditions are met and then repeating each determining step in sequence and incrementing the counter until a predetermined number of increments have been completed.

4. The method of claim 2 wherein the step of verifying the determining steps includes incrementing a timer the first time that all of the determining step conditions are met and then repeating each determining step in sequence and incrementing the timer until a predetermined number of increments have been completed.

5. The method of claim 1 further comprising the step of determining whether the transmission is in its converter mode prior to the step of logging the fault code.

6. The method of claim 1 wherein the step of logging a fault code further comprises enabling a warning indicator.

7. The method of claim 1 wherein the step of logging a fault code further comprises limiting the maximum engine speed.

8. A method for detecting vehicle speed sensor failure, comprising:

determining whether a vehicle speed value is below a maximum threshold speed value;

determining whether a fueling rate value is above a minimum threshold fueling value;

determining whether an engine speed value is above a minimum threshold value;

determining whether the vehicle transmission is in a converter mode; and

logging a fault code further comprises limiting the maximum engine speed.

9. The method of claim 8 wherein the step of logging a fault further comprises limiting the maximum engine speed.

10. A method for detecting vehicle speed sensor failure, comprising:

determining whether a vehicle speed value is below a maximum threshold speed value;

determining whether an engine speed value is above a minimum threshold value;

determining whether the vehicle transmission is in neutral;

determining whether the vehicle transmission is in a converter mode; and

logging a fault code in the engine controller.

11. The method of claim 10 wherein the step of logging a fault code also includes limiting the maximum engine speed.

12. The method of claim 10 further comprising determining whether a fueling value is above a minimum threshold fueling value.

13. The method of claim 10 further comprising verifying that the conditions determined in each of the determining steps are present for a minimum threshold period of time.

14. The method of claim 13 wherein the step of verifying the determining steps includes incrementing a counter the first time that all of the determining step conditions are met and then repeating each determining step in sequence and incrementing the counter until a predetermined number of increments have been completed.

15. The method of claim 13 wherein the step of verifying the determining steps includes incrementing a timer the first time that all of the determining step conditions are met and then repeating each determining step in sequence and incrementing the timer until a predetermined number of increments have been completed.

16. The method of claim 10 wherein the step of logging a fault code further comprises enabling a warning indicator.