Do I need a scan tool to check for codes on a 89 s-10 Blazer 4.3

 

Here is a good description from another forum:

http://www.s10planet.com/forum/showt...ght=paper+clip



pulling your own codes.
To enter the diagnostics, either connect a scan tool to the ALDL/DLC (thats the plug under the dash on the drivers side) connector or use a jumper wire to connect terminals A and B and begin flash diagnosis.

On carbureted vehicles, the jumper should be connected with the ignition switch turned ON to begin code display.

For fuel injected vehicles, the jumper should be connected with the ignition OFF, then with the jumpers in place, the switch should be turned ON to begin code read out.

In both cases, the engine should NOT BE RUNNING. Once the jumper is properly connected, the control module will enter the diagnostic program and report trouble codes on the scan too or by flashing the SES/check engine light.

All codes are 2 digits between 12 and 82. Codes are displayed on the CHECK ENGINE or SERVICE ENGINE SOON light by flashing the MIL with short and long pauses to distinguish digits of 1 from digits of another.The short pause is used between digits of the same code, long pauses are between codes. For Code 12, the sequence will be: flash, pause, flash-flash, long pause

1. When the diagnostic mode is entered, Code 12 is displayed 3 times. This indicates that the internal diagnostic is operating. If Code 12 is not displayed, the self-diagnostic program is not functioning properly. If no systems malfunctions have been stored, Code 12 will continue to repeat.

On many applications, entering dignostic mode will cause solenoids and relays to activate. Pulse-width modulated solenoids may be rapidly energized and de-engergized, causing a clicking noise. Do not be startled by or concerned with this underhood noise during self-diagnosis code display.

2. After code 12 flashes to indicate diagnostic display, any existing system fault codes are displayed in order from lowest to highest code number. Each code is displayed 3 times, followed by the next code if any.

3. When all codes have been displayed, Code 12 will flash again.

This is a pic of the cheap-o scan tool I have (Had it for years but it was around 20 bucks), a chiltons book which I highly suggest getting if your gonna work on your own truck (also around $20), and I'm using a piece of 14 gauge copper wire to show you how to jump the diagnostic port out (I'm an electrician so I have it laying around but a paper clip is what is normally suggested).





Here are 2 pics of where you need to put the jumper wire if you don't have a scan tool.

 

Dang I think I've seen that somewhere before, lmao

 

Ha!

TroubleCodes.net has a pretty comprehensive code listing.