How do i fix a problem indicated by a trouble code # 12

1988-98 Chevy and GMC C/K 1500/2500/3500 Pickup Trucks ...

https://haynes.com > en-us > tips-tutorials > 1988-98-ch...
OBD-I trouble code chart ; 32, Exhaust Gas Recirculation (EGR) failure, Check the vacuum source and all vacuum lines. Check the system electrical connectors at ...

OBD1 Codes - Trouble Code List & Reading (GM) - Mechanic ...

https://mechanicbase.com > OBD Codes
Jan 15, 2022 - In this guide, we will go through everything you have to know about OBD1 Trouble Codes. Learn to read the trouble codes without a scanner ...
‎OBD1 Trouble Code List · ‎OBD1 Connector Wirings Pinout

GM OBD/OBD2 Codes - TroubleCodes.net

https://www.troublecodes.net > gm
GM Specific Codes ; 64. MAP sensor voltage low; RH side O2 sensor lean ; 65, RH side O2 sensor rich ; 66. 3-2 Control solenoid circuit fault(4L60-E); A/C pressure ...

GM OBD I Trouble Code Chart - RepairPal

https://repairpal.com > gm-obd-i-code-chart
Jul 5, 2018 - GM OBD I Trouble Code Chart ; Code 15, Engine coolant temp sensor error (low temp indicated) ; Code 16, System voltage too low ; Code 17, Camshaft position sensor ...
‎Code 12 · ‎Code 32 · ‎Code 42
GM OBD Trouble Code 12
Sept 5, 2012
GM OBD Trouble Code 32
Sept 5, 2012
GM OBD Trouble Code 33
Sept 5, 2012
GM OBD Trouble Code 22
Sept 17, 2012
More results from repairpal.com

If you had two blinking CEL codes, a 12 (pause) and a 55, the code 12 means the battery has been disconnected within the previous 50 starts. The code 55 indicates the end of stored codes. Therefore, you have no saved trouble codes (disconnecting the battery deletes saved trouble codes).

Code 12 doesn't need fixed. When you begin to test codes you will get the code 12 but that is just telling you that it is in diagnostic mode, it will flash the code 12 three times, then after that it will flash all stored trouble codes. After all stored trouble codes have been displayed, the ECM will repeat the process( so getting code 12 again means you have reached the end of the stored codes list) If it displays code 12 three times and then displays code 12 again , it means you have no problem codes.

code 12 indicates that your in diagnostic mode

P 1765 indicates trans 12 volt supply relay CTRL circuit has a problem. Code073 indicates "ambient temperature sensor reads high.

Reading Codes OBD-I Systems Fig. 1: Diagnostic trouble codes — 4.5L engine
Fig. 2: Diagnostic trouble codes — 4.9L engine
Fig. 3: Diagnostic trouble codes — 4.6L engine
Listings of the trouble codes for the various engine control systems covered in this manual are located in this section. Remember that a code only points to the faulty circuit NOT necessarily to a faulty component. Loose, damaged or corroded connections may contribute to a fault code on a circuit when the sensor or component is operating properly. Be sure that the components are faulty before replacing them, especially the expensive ones. The Assembly Line Diagnostic Link (ALDL) connector or Data Link Connector (DLC) may be located under the dash and sometimes covered with a plastic cover labeled DIAGNOSTIC CONNECTOR.

1. On all 1990–95 models the diagnostic trouble codes can be read by grounding test terminal B. The terminal is most easily grounded by connecting it to terminal A (internal ECM ground). This is the terminal to the right of terminal B on the top row of the ALDL connector.
2. Once the terminals have been connected, the ignition switch must be moved to the ON position with the engine not running.
3. The Service Engine Soon or Check Engine light should be flashing. If it isn't, turn the ignition OFF and remove the jumper wire. Turn the ignition ON and confirm that light is now on. If it is not, replace the bulb and try again. If the bulb still will not light, or if it does not flash with the test terminal grounded, the system should be diagnosed by an experienced driveability technician. If the light is OK, proceed as follows.
4. The code(s) stored in memory may be read through counting the flashes of the dashboard warning lamp. The dash warning lamp should begin to flash Code 12. The code will display as one flash, a pause and two flashes. Code 12 is not a fault code. It is used as a system acknowledgment or handshake code; its presence indicates that the PCM can communicate as requested. Code 12 is used to begin every diagnostic sequence. Some vehicles also use Code 12 after all diagnostic codes have been sent.
5. After Code 12 has been transmitted 3 times, the fault codes, if any, will each be transmitted 3 times. The codes are stored and transmitted in numeric order from lowest to highest. NOTE: The order of codes in the memory does not indicate the order of occurrence.
   
6. If there are no codes stored, but a driveability or emissions problem is evident, the system should be diagnosed by an experienced driveability technician.
7. If one or more codes are stored, record them. Refer to the applicable Diagnostic Code chart in this section.
8. Switch the ignition OFF when finished with code retrieval or scan tool readings. NOTE: After making repairs, clear the trouble codes and operate the vehicle to see if it will reset, indicating further problems.
   

this means there is a problem if it continuosly flashes
Short-circuit terminal 8 of the self-diagnostic
connector to GND to display the trouble code on the
CHECK lamp.
If no trouble codes exist, code “12” is displayed continuously.
If trouble codes exist, code “12” is displayed three times, and then other trouble codes, starting from the smaller code number, these are displayed three times respectively.

this is located behind right front centre console side trim..