Speedometer - Maximum Permissible Error

Group 62
Instruments

Bulletin Number
62 02 96

Woodcliff Lake, NJ
May 1996
Product Engineering

SUBJECT:
Maximum Permissible Speedometer Error

MODELS:
All

General Information:

A certain amount of "speedometer advance" is necessary to compensate for negative tolerances in tire diameter, electronic controls, and other factors. This advance reduces the risk of the speedometer displaying a speed that is less than the vehicle's actual speed.

The amount of speedometer advance can be calculated by inputting a frequency (using the DIS Tester, "Kombi Test Schedule") that corresponds to a given speed and noting the speed that is indicated by the speedometer. The maximum permitted speedometer advance is 10% of the actual (input) speed plus 2.4 mph.

Example:
Actual Speed = 50 mph
50 mph x 10% = 5 mph; 5 mph + 2.4 mph = 7.4 mph
Therefore, the permissible displayed speed is 50 to 57.4 mph.

(Note: The displayed speed must never be less than the actual speed).

No repairs should be attempted if the speedometer advance is within 10% + 2.4 mph.

NOTE:
The amount of speedometer advance has no effect on recording of accumulated mileage in the odometer display. The odometer records total mileage digitally and does not incorporate any "advance" tolerances.

Warranty Status: Information Only.