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.

Here is a picture of the connector where you get the 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 normal
13 oxygen sensor circuit open
14 coolant sensor high resistance or shorted
15 coolant sensor circuit low or open
16 direct ignition system (DIS) fault in circuit
17 cam position sensor fault
18 crank or cam sensor error
19 crank sensor circuit fault
21 tps sensor out of range
22 tps sensor signal voltage low
23 intake air temp sensor out of range, low
24 vehicle speed (vss) sensor circuit fault
25 air temp sensor sensor out of range, high
26 quad-driver module (computer) circuit #1 fault
27 quad-driver module (computer) 2nd gear circuit
28 quad-driver module (computer) circuit #2 fault
29 quad driver module (computer) 4th gear circuit
31 cam position sensor fault
32 egr circuit fault
33 map sensor signal out of range, high
34 map sensor signal out of range, low
35 idle air control sensor circuit fault
36 ignition system circuit error
38 brake input circuit fault
39 clutch input circuit fault
41 cam sensor circuit fault, igntion control circuit fault
42 electronic spark timing (EST) circuit grounded
43 knock sensor or electronic spark control circuit fault
44 oxygen sensor lean exhaust
45 oxygen sensor rich exhaust
46 pass-key II circuit or ps.pressure switch circuit fault
47 pcm-bcm data circuit
48 misfire diagnosis
51 calibration error, mem-cal, ecm or eeprom failure
52 engine oil temperature circuit, low temperature indicated
53 battery voltage error or egr or pass-key II circuit
54 egr system failure or fuel pump circuit low voltage
55 a/d converter error or pcm not grounded or lean fuel or frounded reference voltage
56 quad-driver module #2 circuit
57 boost control problem
58 vehicle anti-theft system fuel enable circuit
61 a/c system performance or degraded oxygen sensor signal
62 engine oil temperature high temperature indicated
63 oxygen sensor right side circuit open or map sensor out of range
64 oxygen sensor right side lean exhaust indicated
65 oxygen sensor right side rich exhaust indicated
66 a/c pressure sensor circuit low pressure
67 a/c pressure sensor circuit or a/c clutch circuit failure
68 a/c compressor relay circuit failure
69 a/c clutch circuit head pressure high
70 a/c refrigerant pressure circuit high
71 a/c evaporator temperature sensor circuit low
72 gear selector switch circuit
73 a/c evaporator temperature circuit high
75 digital egr #1 solenoid error
76 digital egr #2 solenoid error
77 digital egr #3 solenoid error
79 vehicle speed sensor (vss) circuit signal high
80 vehicle speed sensor (vss) circuit signal low
81 brake input circuit fault
82 ignition control (IC) 3X signal error
85 prom error
86 analog/digital ecm error
87 eeprom error
99 power management

NOTES:

The above list can be used on most GM vehicles such as Buick, Pontiac, Oldsmobile, Chevrolet and some models of Cadillac. To make sure you have the right code and also fix it, please contact ATS.

Tip #1 Resetting your codes 1985-95 obd1

The first rule of engagement when you see the "check engine light" in your dash panel is to get the code. As soon as you get it, write it down. Then reset your code by disconnecting the battery negative terminal for 1 minute and reconnect. You can then start the engine and take the vehicle for a quick road test of say 20-30 minutes. If the same check engine light shows up again with the same code, then THAT code is the real culprit that you have to fix.

Notes:

Most domestic cars and trucks computer (from early 80s to late 90s) can be reset using the battery disconnection method above (or you can remove the ecm fuse to reset the code). However, beware of some imports because battery disconnection will not work and might require your vehicle computer reprogrammed by the dealer. Before doing so, please contact your dealer or you can inquire at http://www.automotivetroubleshootingsecrets.com if you are a member.

Most domestic and imported cars and trucks have its own system to retrieve the code yourself. Most of these models are made before 1995 for domestic vehicles and 1993 for imported vehicles. After that, you need a scanner to retrieve the engine fault code.

Check Engine Light Codes BASICS

Understanding your “check engine light codes” in your dash panel is the easiest way to begin troubleshooting your vehicle problem. These diagnostic trouble codes show up in your dash panel for a purpose: to lead you to the defective sensor or circuit causing your vehicle problem. Once you get the codes, you are on your way in fixing the check engine light in your dash.

Check engine light codes:

The first strategy in getting your vehicle fixed is to find the check engine light codes or diagnostic trouble codes showing at your dash panel. Once you know how it is done, you still have to know how to reset the code for testing. It is also called “reset check engine light”. However, before you can do all of these, you need to check the engine troubleshooting basics as shown below.


Start with the Basics!

Before attempting to troubleshoot your check engine light codes, make sure you cover these basic checks like:
When is the last tune up done? All fluid levels OK?
Visual checks like all vacuum hoses connected? Electrical wires plugged in? Ground wires cleaned and tight?
Brief history like what work done on it lately? Any parts changed? Any change after the repair? (Usually when a repair is done and a bad changed happened, it means something wrong was done during the repair).
Once the above are checked and verified, you are now ready to check the diagnostic trouble codes in you dash panel.


Quick Computer Check in less than 1 minute!


This can be used for most car or trucks if you want to know if you have any engine computer/sensor malfunctions. Turn ignition key on without starting and note the “check engine light” coming on in the dash panel. Once you got it started, that same light should go out in seconds. If the light stays on or did not come at all, then either your computer/sensor or wirings are defective. Once you established this, you can begin tracking the code.


Tracking your diagnostic trouble codes


There are 2 diagnostic systems available depending on the model of your vehicle. For domestic vehicles, between 1983-1995, OBD1 is used and OBD2 is used from 1996 up to the present. For imported vehicles, OBD1 is good only up to 1993 and OBD2 starts in 1994 up to the present. The good news is: OBD1 can usually be done yourself whereas you need a scanner for OBD2 codes.