So, I noticed my check engine light is on, so I took my truck to auto zone to read the code. They hooked up their OBD code scanner to the OBB 1 port. Unfortunately their scanner just kept repeating that I needed to turn my key on. We had the larger black plug, as well as the small grey plug, both plugged into the code scanner.

After that I went home, ordered my own scanner, and went over all of my fuses. No fuses are blown anywhere on the truck, it runs and drives very well “a little rich”. But my check engine light stays on, and my code scanner just reads 000. I have even tried using the paper clip method to jump over the wires and try to read the check engine light flashes, but even that doesn’t work. Any ideas??

 

Welcome to the forum

What YEAR Ranger and what engine?

Unhook either battery cable for 5 minutes, that will clear codes in OBD1
It also resets computer

Then try hooking up scanner to see if it can communicate with computer

The CEL will come back on if there is a problem with the system after driving a bit
But first thing is to get the OBD1 reader working
The "paper clip" method is what the OBD1 readers use, so same thing, the "paper clip" method is used when you do not have an OBD1 reader, its not a different "method"

So reset computer and then try connecting

 

Thanks for the reply! I have disconnected my battery several times to reset my computer. The check engine light does come back on, but unfortunately my Code Scanner still doesn’t get any codes from the OBD port. I have also tried using a paper clip to try reading the CEL flashes, but unfortunately the CEL just stays illuminated the entire time, so there are no flashes to read.

 

I don't think 1989 CEL will flash codes, need a test light or analog volt meter, and it will be 2 digit codes not 3 digit

Pull the computer and open it up, its in the passenger side of cab behind the kick panel

Check the 2 or 3 capacitors, they are blue or black cylinders that stick up
These leak and cause issues with circuits
Under $5 to replace them, and its FREE to have a look
Also just a general inspection of the circuit board, AND the connector and pins, looking for corrosion

Clean with isopropyl alcohol and Q-tips

 

Thank you! I will try this and let you know what I find out!

 

I was able to get my obd port working! Turns out, it somehow was not getting a ground, so I grounded the small grey plug to the frame, and that allowed the code reader to work!

 

Good stuff

Have heard of the fuse blowing but not the ground "blowing", lol