Equus 3120 - OBD 2&1 Tool Kit - Manual (Page 72)

70 OBD2 & 1
E
GM OBD1 Systems
CODE RETRIEVAL PROCEDURE
Code 12 will always be present and it has one of the following mean-
ings:
■ If code 12 is the only DTC retrieved and your vehicle "STARTS OK"
then code 12 indicates system "PASS" and all computer control
systems are functioning properly.
■ If code 12 is present and your vehicle "DOES NOT START", then it
may indicate a problem with the ignition control system.
7. Disconnect the Tool from the vehicle and turn the ignition key OFF.
8. To prolong battery life, the Tool automatically shuts "Off" after
approximately three minutes with no button activity. The DTCs
retrieved will remain in the Tool's memory, and may be viewed at
any time. If the Tool’s batteries are removed, or if the Tool is re-
linked to a vehicle to retrieve codes, any prior codes in its memory
are automatically cleared.
■ See Viewing DTCs in the Tool’s Memory on page 13 to view
DTCs stored in the Tool’s memory.
9. Follow the testing and repair procedures outlined in the vehicle's
service repair manual to correct "hard" DTCs. Codes should be
addressed and eliminated in the order they were received, erasing
(see Erasing DTC's on page 80) and retesting after each repair is
made to be sure the fault was eliminated. Code 12 will appear alone
when no other fault codes are present.
■ It may be necessary to test drive the vehicle to reset "hard" fault
codes 13, 15, 24, 44, 45, and 55 after they have been erased.
Whenever codes 51, 52, 54, or 55 are displayed with other
codes, troubleshoot and eliminate the "50 Series" codes first,
then proceed with the lower numbered codes.
The green, yellow and red LEDs are used (with the LCD dis-
play) as visual aids to make it easier to determine engine sys-
tem conditions. See Servicing Diagnostic Trouble Codes
on page 78 for information on interpreting LEDs and servic-
ing DTCs.