Equus 3123 - GM Code Reader (1982 - 1995) - Manual (Page 13)

Retrieving ECM Codes
GM 2-4
• Each code is transmitted three times before the next code
is sent.
• Code sets will begin with Code 12 ("System Pass") even if
fault codes are present.
• The codes will continue to be sent as long as the ignition is
on and the Code Reader is connected.
• Count blinks to get the service codes:
• Code 12 looks like:
NOTE: Code 12 is not a fault code. Code 12 indicates the
computer's self-diagnostic system is functioning
properly (SYSTEM PASS). If code 12 is the only code
which displays when you perform the diagnostic test,
this means there are no fault codes stored in the
vehicle's computer. Consult your vehicle's repair
manual for "no codes" problems.
• Code 22 looks like:
IMPORTANT: Any code that ends in zero ("0") is transmitted
as follows:
• Code 30 looks like:
6. Next, erase service codes (see paragraph 2.4). This will
help you determine which codes are "hard" faults and
which codes are "intermittent" faults.
7. Turn on ignition, start engine, and observe "Service
Engine Soon" light; light should turn off. Run engine for
several minutes (to allow engine to reach normal
operating temperature), then observe "Service Engine
Soon" light:
■ If "Service Engine Soon" light turns on, turn off ignition
and repeat steps 2 through 5. This reveals "hard" fault
codes.
ABNORMALLY LONG PAUSE
BLINK BLINK
= Code 30
BLINK
BLINK BLINK
PAUSE
BLINK BLINK
= Code 22
BLINK
PAUSE
= Code 12
BLINK BLINK