How To Retrieve OBD I Trouble Codes (1988-1995 4.3L V6 Chevrolet S10 Pickup, GMC Sonoma)

Diagnostic Link Connector Location. How To Retrieve OBD I Trouble Codes (1988, 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995 4.3L V6 Chevrolet S10 Pickup, GMC S15 Pickup, GMC Sonoma)

Are you dealing with a pesky check engine light in your pre-1996 4.3L V6 Chevrolet S10 pickup (GMC S15 pickup, GMC Sonoma)? It can seem like a daunting task to retrieve the diagnostic trouble codes, but don't worry - this tutorial will help!

In this guide, I'll cover how to use the on-board diagnostic (OBD) system to display the trouble codes stored in the fuel injection computer and which diagnostic link connector (DLC) terminals need to be jumpered in order to retrieve the diagnostic trouble codes (DTCs).

Keep reading for all the details you need to get your Chevy S10 pickup (GMC S15 pickup, GMC Sonoma) back on the road!

Reading The On/Off Flashes Of The Check Engine Light

Identifying The ALDL Terminals To Jumper To Read The On/Off Flashes Of The Check Engine Light (How to Retrieve GM OBD I Diagnostic Trouble Codes)

The diagnostic link connector (DLC), also known as the Assembly Line Data Link (ALDL) connector, is located under the dash, usually on the right side of the steering wheel column.

This connector is the same across all pre-OBD II GM vehicles. You can see what the ALDL connector looks like in the photo at the beginning of this tutorial.

In order to retrieve the diagnostic trouble codes stored in the memory of the fuel injection computer, you'll need "jumper" two terminals together. You can use a paper clip or a small piece of wire with both ends stripped.

These are the steps to retrieve the trouble codes:

  1. Make sure your battery is fully charged before starting (its customary to place a charger on the battery while retrieving trouble codes to keep the battery from discharging).
  2. Turn the key to the ON position but don't start the vehicle.
  3. Jumper terminals A and B, of the diagnostic link connector, together.
  4. If no trouble codes are present:
    • The MIL will flash a code 12 (see illustration below) which consists of one flash, a short pause, then two flashes in rapid succession. Code 12 would look like this:
      • ‘Flash’, pause, ‘flash’, ‘flash’, long pause.
    • Code 12 will is repeated another 2 times (all codes are flashed 3 times before the next one).
  5. If trouble codes are present:
    • The MIL will flash code 12 three times and then any other codes stored.
    • Each trouble code, in addition to code 12, is flashed 3 times.
    • A code 22 would look like this:
      • ‘Flash’, ‘flash’, pause, ‘flash’, ‘flash’, long pause.

Once you've confirmed and written down the trouble codes, remove the jumper wire from the diagnostic link connector (DLC) and turn the key to the Off position.

How To Read The On/Off Flashes Of The Check Engine Light (How to Retrieve GM OBD I Diagnostic Trouble Codes). 1988, 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995 4.3L V6 Chevrolet S10 Pickup, GMC S15 Pickup, GMC Sonoma.

GM OBD I Diagnostic Trouble Code Definitions

Chevy S10/GMC S15 OBD I Trouble Code Definitions
Code Description
12 System Check
13 Oxygen Sensor Circuit
14 Engine Coolant Temperature (ECT) High Temperature Indicated
15 Engine Coolant Temperature (ECT) Sensor Signal Voltage High
16 Transmission Speed Error
21 TPS Signal Voltage High
22 TPS Signal Voltage Low
23 MAT (Manifold Air Temperature) Signal Voltage High
24 Vehicle Speed Sensor (VSS) Signal Voltage High
25 MAT (Manifold Air Temperature) Signal Voltage Low
26 Quad Driver 1 Fault (4.3L M/T only)
27 Quad Driver 2 Fault (4.3L M/T only)
28 Transmission Pressure Switch Manifold Range Circuit Problem
32 EGR System Failure
33 MAP Sensor Signal Voltage High
34 MAP Sensor Signal Voltage Low
35 Idle Speed Error
37 Brake Switch Stuck On (4L60-E A/T only)
39 Knock Sensor Circuit Shorted (4.3L M/T Only)
42 Electronic Spark Timing (EST) Fault
43 Electronic Spark Control (ESC) Fault
44 Lean Exhaust
45 Rich Exhaust
51 PROM/MEM-CAL Fault
51 System Voltage High (Charging System Problem)
54 Fuel Pump Circuit
54 Faulty ECM/PCM/VCM

Pinout Of the ALDL Connector Terminals. How to Retrieve GM OBD I Diagnostic Trouble Codes. 1988, 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995 4.3L V6 Chevrolet S10 Pickup, GMC S15 Pickup, GMC Sonoma.

More 4.3L Chevy S10 Pickup, GMC S15 Pickup, And GMC Sonoma Tutorials

You can find a complete list of 4.3L Chevy S10 pickup, GMC S15 pickup, And GMC Sonoma tutorials here:

Here's a sample of the tutorials you'll find in the index:

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Chevrolet Vehicles:

  • S10 Pickup 4.3L
    • 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995

GMC Vehicles:

  • S15 Pickup 4.3L
    • 1988, 1989, 1990
  • Sonoma 4.3L
    • 1991, 1992, 1993, 1994, 1995