GM Trouble Code Info

Accessing Trouble Codes

Turn ignition switch to OFF position

Locate Data Link Connector (DLC), see image below.

Jumper the A&B terminals(a paper clip or a jumper wire work ok)

Turn Ignition switch to ON position.

Count the flashes on the "CHECK ENGINE" or "SERVICE ENGINE" light.

FLASH, pause, FLASH, FLASH = code 12

NOTE: Some 94 & 95 models do not have the B terminal. In which case a scanner is required.

NOTE: Some 94 & 95 models that DO have the A & B terminals still require a scanner.

All vehicles after 96 are OBDII,and require a scanner to access them.

12 Pin DLC

A - Ground	F - TCC
B - Test Terminal	G - Fuel Pump
C - Air Injection	H - Brake Sense Speed Input
E - Serial Data	M - Serial Data

Clearing Trouble Codes

Diagnostic trouble codes may be cleared by disconnecting the battery ground cable for at least 20 seconds. Reconnect negative battery cable and recheck codes to confirm the repair.

Diagnostic Codes

Select your Vehicle or look below for Generic codes.
Year	Eng	8th digit of the VIN Number
82-83	2.5L	All
82-83	3.0L	All
86	1.8L	Multi Port Fuel Injection, VIN J
86	1.8L	Throttle Body Injection, VIN 0
86	2.0L	Throttle Body Injection, VIN P
86	2.5L	Throttle Body Injection, VIN 2
86	2.8L	Carb, VIN X
86	3.8L	Fuel Injection, VIN B
86-87	3.8L	Carb, VIN A
86-87	4.1L	4.1L Fuel Injection, VIN 8
86-87	5.0L	5.0L Carburetor, VIN 9
86-88	2.5L	Throttle Body Injection, VIN U
86-88	2.5L	Throttle Body Injection, VIN R
86-88	2.8L	Multi Port Fuel Injection, VIN 9
86-88	3.0L	Multi Port Fuel Injection, VIN L
86-88	3.8L	Fuel Injection, VIN 7
86-88	3.8L	Fuel Injection, VIN 3
86-88	5.0L	Carburetor, VIN H
86-88	5.0L	Carburetor, VIN G
86-88	5.7L	Fuel Injection, VIN 8
86-88	5.7L	Carburetor, VIN 6
86-89	2.8L	Multi Port Fuel Injection, VIN W
86-89	2.8L	Multi Port Fuel Injection, VIN S
86-89	5.0L	Fuel Injection, VIN F
86-90	4.3L	Throttle Body Injection, VIN Z
87-88	2.0L	Throttle Body Injection, VIN 1
87	2.8L	Throttle Body Injection VIN R
87-88	4.1L	Multi Port Fuel Injection, VIN 7
87-90	2.0L	Multi Port Fuel Injection, VIN M
87-90	5.0L	Carb, VIN Y
87-91	2.0L	Throttle Body Injection, VIN K
88-89	2.3L	Multi Port Fuel Injection, VIN D
88-89	3.1L	Multi Port Fuel Injection, VIN T
88-89	4.5L	VIN 5
88-90	3.8L	VIN C
88-93	5.0L	Throttle Body Injection, VIN E
89	2.0L	Throttle Body Injection, VIN 1
89	2.3L	Multi Port Fuel Injection, VIN A
89	3.1L	Multi Port Fuel Injection, VIN V
89	5.7L	VIN 8
89-90	5.7L	Throttle Body Injection, VIN 7
89-95	5.7L	VIN K
89-91	2.5L	Throttle Body Injection, VIN R
89-91	3.3L	Multi Port Fuel Injection, VIN N
90	2.3L	Multi Port Fuel Injection, VIN D
90	2.3L	Multi Port Fuel Injection, VIN A
90	3.8L	VIN L
90	4.5L	VIN 3
90	5.7L	VIN J
90-91	2.2L	Throttle Body Injection, VIN G
90-91	3.1L	Multi Port Fuel Injection, VIN V
90-91	5.0L	VIN F
90-91	5.7L	VIN 8
91	2.3L	Multi Port Fuel Injection, VIN D
91	2.3L	Multi Port Fuel Injection, VIN A
91	3.8L	VIN C
91	3.8L	VIN L
91	4.9L	VIN B
91	5.7L	Throttle Body Injection, VIN 7
91	5.7L	VIN J
91-92	1.9L	Throttle Body Injection, VIN 9
91-92	1.9L	Single Port Fuel Injection, VIN 7
91-92	3.4L	Multi Port Fuel Injection, VIN X
92	2.0L	Multi Port Fuel Injection, VIN H
92	2.2L	VIN 4
92	2.3L	Multi Port Fuel Injection, VIN D
92	2.3L	Multi Port Fuel Injection, VIN A
92	2.3L	Multi Port Fuel Injection, VIN 3
92	2.5L	Throttle Body Injection, VIN R
92	5.0L	VIN F
92	5.7L	Throttle Body Injection, VIN 7
92	5.7L	VIN J
92	5.7L	VIN 8
92-93	3.3L	Multi Port Fuel Injection, VIN N
92-93	3.8L	general & Supercharged
92-93	4.3L	Throttle Body Injection, VIN Z
92-93	4.9L	VIN B
92-93	5.7L	VIN P
92-95	3.8L	VIN L
93	2.0L	Multi Port Fuel Injection, VIN H
93	2.2L	VIN 4
93	2.3L	Multi Port Fuel Injection, VIN D
93	2.3L	Multi Port Fuel Injection, VIN A
93	2.3L	Multi Port Fuel Injection, VIN 3
93	2.5L	VIN A
93	3.1L	Fuel Injection, VIN T
93	5.7L	Throttle Body Injection, VIN 7
93	5.7L	VIN J
93-94	1.9L	Throttle Body Injection, VIN 9
93-95	1.9L	VIN 7
93-95	3.4L	VIN X
93-95	3.4L	VIN S
93-95	4.3L	VIN W
93-95	4.6L	VIN Y
93-95	4.6L	VIN 9
94	2.0L	Multi Port Fuel Injection, VIN H
94	2.2L	VIN 4
94	2.3L	Multi Port Fuel Injection, VIN D
94	2.3L	Multi Port Fuel Injection, VIN A
94	2.3L	Multi Port Fuel Injection, VIN 3
94	3.1L	Multi Port Fuel Injection, VIN T
94	5.7L	VIN P
94-95	3.1L	VIN M
94-95	4.3L	VIN Z
94-95	4.9L	VIN B
94-95	5.7L	VIN J
94-95	6.5L	6.5 Diesel
95	1.9L	Throttle Body Injection, VIN 8
95	2.2L	VIN 4
95	2.3L	Multi Port Fuel Injection, VIN D
95	5.7L	VIN P
96	5.7L	VIN P OBDII
96	5.7L	VIN 5 OBDII
96	6.5L	6.5L Diesel
97	6.5L	6.5L Diesel

GM Generic Codes

Without Onboard Diagnostics (OBD-II)
12	Diagnostic mode	44	O2 sensor (lean exhaust)
13	O2 sensor or circuit	45	O2 sensor(exhaust rich)
14	coolant sensor/high temp	46	vehicle anti-theft system
15	coolant temp/low temp	47	air condition clutch and cruise circuit
16	system voltage high (3.8L) DIS circuit	51	PROM,MEM CAL or ECM problem (3.1L)
17	crank signal circuit ECM fault crank position sensor circuit (3.8L)	52	CALPK or ECM problem (3.1L)
18	crank signal circuit ECM fault injector circuit (vin P-5.7L)	53	system overvoltage EGR system (carb models) alternator out of range
19	fuel pump circuit(shorted) crank position sensor(88-91)	54	fuel pump circuit EGR fault (3.8L)
20	fuel pump circuit (open)	55	O2 sensor or ECM
21	TPS circuit	56	vacuum sensor Quad drvier B (3.8L)
22	TPS out of adjustment	58	Trans code-TTS temp high
21/22	grounded WOT circuit	59	Trans code-TTS temp low
23	MAT circuit IAC sensor (95 models)	61	O2 sensor signal faulty
24	vehicle speed sensor	63	MAP sensor voltage high
25	MAT circuit	64	MAP sensor voltage low RH side O2 sensor lean
26	Quad driver circuit Throttle switch shorted	65	RH side O2 sensor rich
27	throttle switch open	66	3-2 Control solenoid circuit fault(4L60-E) A/C pressure sensor circuit out of range
28	Transmission range pressure switch	67	TCC solenoid circuit (4L60-E)
31	park/neutral switch cam sensor circuit EGR circuit (88-90) MAP sensor (shorted)	68	O/D ratio error (4L80-E)
32	BARO sensor circuit(carb models) EGR circuit(injected models) MAP sensor(open)	69	TCC stuck on (4L60-E &4L80-E) A/C head pressure switch circuit
33	MAP sensor(low vacuum) MAF sensor MAP sensor(voltage high)	72	VSS circuit loss transmission output signal
34	MAP sensor(voltage low) MAF sensor	73	trans pressure control solenoid
35	IAC valve or circuit idle speed control circuit(shorted)	74	Trans input speed error (4L80-E)
36	MAF sensor DIS system(quad 4) transaxle shift control (3.8L)	75	system voltage low
37	MAT sensor temp high (3.8L) brake switch(4L60-E trans)	79	Transmission fluid temp high
38	brake input circuit MAT sensor temp low(84-86)	81	transmission 2-3 error
39	TCC knock sensor shorted(4.3L)	82	transmission 1-2 error
40	power steering pressure switch	83	TCC solenoid circuit fault
41	faulty ignition module cam sensor (3.8L)	85	undefined gear ratio
42	EST circuit	86	low gear ratio error
43	ESC circuit knock sensor signal	87	high gear ratio error