CYL GP-BASIC 4392216 - Caterpillar

"DIAGNOSTIC" lamp is used to indicate the existence of an active fault by flashing codes.When the ignition switch is first turned on, the "DIAGNOSTIC" lamp will go through the following procedure:
The "DIAGNOSTIC" lamp will come on and the "DIAGNOSTIC" lamp will remain on for five seconds. This checks the operation of the lamp.
The "DIAGNOSTIC" lamp will turn off.
The "DIAGNOSTIC" lamp will come on again and the "DIAGNOSTIC" lamp will flash codes for any active diagnostic codes. Not all diagnostic codes have a unique flash code.
The "DIAGNOSTIC" lamp will turn off for five seconds.
The "DIAGNOSTIC" lamp repeats all active diagnostic codes.A fault diagnostic code will remain active until the problem is repaired. The electronic control module will continue flashing the flash code at five second intervals until the problem is repaired.