Diagnostic Mode
On a Mark 20 system to enter a diagnostic mode, vehicle speed must be below 10 km/h (6 mph) and no ABS condition present. If vehicle speed is not below 10 km/h (6 mph), a "no response" message could be displayed by the DRBIII(r). The following are characteristics of diagnostic mode:^ The amber ABS and red brake warning indicator will blink rapidly (about 1/2 second on and 1/2 second off). If a hard trouble code is present, such as a CAB Power Feed Circuit diagnostic trouble code, the indicator will be illuminated without blinking until the diagnostic trouble code condition is corrected.
^ Antilock operation is disabled.