it is the 12 pin
You can retrieve codes using the method outlined below.
GM 1983-95 vehicles OBD1 codes self-retrieval
As the name implies, you can get the codes for GM cars or trucks yourself if the model of your vehicle is made before 1995, this means as soon as you see "check engine light" in your dash, you can get the code in minutes if you want.
Shown on the left is a picture of the connector where you get the GM OBD1 code.
When you find the adapter connector, use a jumper wire (see red wire above) and connect terminals A and B. Next turn your key on but don't start. Watch your check engine flash the code/s.
EXAMPLE: CODE 12: one long flash and two short flashesCODE 13: one long flash and 3 short flashes.
Note: code 12 is usually the first code you get and just ignore it.Watch the code after code 12, that's what you need.
GM common codes for OBD1 (for vehicles made before 1995)12 System normal13 oxygen sensor circuit open14 coolant sensor high resistance or shorted15 coolant sensor circuit low or open16 direct ignition system (DIS) fault in circuit17 cam position sensor fault18 crank or cam sensor error19 crank sensor circuit fault21 tps sensor out of range22 tps sensor signal voltage low23 intake air temp sensor out of range, low24 vehicle speed (vss) sensor circuit fault25 air temp sensor sensor out of range, high26 quad-driver module (computer) circuit #1 fault27 quad-driver module (computer) 2nd gear circuit28 quad-driver module (computer) circuit #2 fault29 quad driver module (computer) 4th gear circuit31 cam position sensor fault32 egr circuit fault33 map sensor signal out of range, high34 map sensor signal out of range, low35 idle air control sensor circuit fault36 ignition system circuit error38 brake input circuit fault39 clutch input circuit fault41 cam sensor circuit fault, igntion control circuit fault42 electronic spark timing (EST) circuit grounded43 knock sensoror electronic spark control circuit fault44 oxygen sensor lean exhaust45 oxygen sensor rich exhaust46 pass-key II circuit or ps.pressure switch circuit fault47 pcm-bcm data circuit48 misfire diagnosis51 calibration error, mem-cal, ecm or eeprom failure52 engine oil temperature circuit, low temperature indicated53 battery voltage error or egr or pass-key II circuit54 egr system failure or fuel pump circuit low voltage55 a/d converter error or pcm not grounded or lean fuel or frounded reference voltage56 quad-driver module #2 circuit57 boost control problem58 vehicle anti-theft system fuel enable circuit61 a/c system performance or degraded oxygen sensor signal62 engine oil temperature high temperature indicated63 oxygen sensor right side circuit open or map sensor out of range64 oxygen sensor right side lean exhaust indicated65 oxygen sensor right side rich exhaust indicated66 a/c pressure sensor circuit low pressure67 a/c pressure sensor circuit or a/c clutch circuit failure68 a/c compressor relay circuit failure69 a/c clutch circuit head pressure high70 a/c refrigerant pressure circuit high71 a/c evaporator temperature sensor circuit low72 gear selector switch circuit73 a/c evaporator temperature circuit high75 digital egr #1 solenoid error76 digital egr #2 solenoid error77 digital egr #3 solenoid error79 vehicle speed sensor (vss) circuit signal high80 vehicle speed sensor (vss) circuit signal low81 brake input circuit fault82 ignition control (IC) 3X signal error85 prom error86 analog/digital ecm error87 eeprom error99 power management
The obd 2 connector is 16 pins and looks like the one below.
There are some 1994 and 1995 models that are obd 1 but use the obd 2 style connector. This requires the use of a scan tool that has the appropriate software and connectors. The Actron CP9145 is such a tool. Check the link below. You can either purchase one of these tools or stop by a repair shop that has the appropriate scan tool. They will likely charge $40-50 to scan the vehicle for you. In the end, you are better off purchasing the tool for $100, as you can use it in the future.
Sorry for the delay. You will need the additional cable in the link below.