[Code of Federal Regulations]
[Title 49, Volume 6]
[Revised as of October 1, 2006]
From the U.S. Government Printing Office via GPO Access
[CITE: 49CFR570.58]

[Page 201]
 
                        TITLE 49--TRANSPORTATION
 
                   CHAPTER V--NATIONAL HIGHWAY TRAFFIC
                    SAFETY ADMINISTRATION, DEPARTMENT
                            OF TRANSPORTATION
 
PART 570_VEHICLE IN USE INSPECTION STANDARDS--Table of Contents
 
         Subpart B_Vehicles With GVWR of More Than 10,000 Pounds
 
Sec.  570.58  Electric brake system.

    (a) Electric brake system integrity. The average brake amperage 
value shall be not more than 20 percent above, and not less than 30 
percent below, the brake manufacturer's maximum current rating. In 
progressing from zero to maximum, the ammeter indication shall show no 
fluctuation evidencing a short circuit or other interruption of current.
    (1) Inspection procedure. Insert a low range (0 to 25 amperes for 
most 2- and 4-brake systems and 0 to 40 amperes for a 6-brake system) 
d.c. ammeter into the brake circuit between the controller and the 
brakes. With the controller in the ``off'' position, the ammeter should 
read zero. Gradually apply the controller to the ``full on'' position 
for a brief period (not to exceed 1 minute) and observe the maximum 
ammeter reading. Gradually return the controller to ``full off'' and 
observe return to zero amperes. Divide the maximum ammeter reading by 
the number of brakes and determine the brake amperage value.
    (b) Electric brake wiring condition. Electric brake wiring shall not 
be frayed. Wiring clips or brackets shall not be broken or missing. 
Terminal connections shall be clean. Conductor wire gauge shall not be 
below the brake manufacturer's minimum recommendation.
    (1) Inspection procedure. Examine visually for conditions specified.