My 1993 Ford Ranger 4.0 4x4 check engine light does not come on, ‘if’ the bulb is good, what’s next to check? Thank you, Bill

 

Welcome to the forum

The CEL or MIL(malfunction indicator light) Bulb, gets 12volts when key is On, then it has a Ground wire that runs back to pin 17 on the engine computer

Computer Grounds the CEL as it boots up, CEL on, then unGrounds it after start up if no urgent codes are present

This Ground wire also runs to the OBD port in the engine bay, in 1993 it should be drivers side between fuse box and firewall may be still hooked to the side of fuse box, may have a cover on it with EEC

Go here: https://therangerstation.com/tech_library/OBD_I.shtml

You will see what the OBD1 port looks like

The slot labelled "Self Test OUT" is this Ground wire

So if you hook up a volt meter or 12v test light to Battery Positive, and then use this slot as the GROUND, with key on you should see 12v if Computer is grounding pin 17

You don't need to use jumper unless you want to read codes, the "Self Test OUT" is just a way to test if computer is Grounding the wire on startup


Ground point-----Computer pin 17---------------------OBD1 connection---------------------instrument cluster(CEL/MIL) Bulb-------------12v fuse for cluster gauges


In my 1994 diagram its a Pink/green wire used from pin 17 to OBD then to cluster


In this picture: http://image.mustangandfords.com/f/1...-test-port.jpg

You can see the OBD plug and the COVER that says EEC test, again you do not need that jumper for this test, its just if you want to read codes

 

Appreciate the information, I will try.