problem with mil not lighting

[rangerstx]

Ok, here's my problem. I have a 85' ranger that I put a 4.0 engine in 3 yrs ago , it runs fine. My dilemma is the MIL light won't come on. Not sure when it quit working. I really wouldn't care but it won't pass smog without it . I've tried testing the light and that is not it......so what I need to know is what turns the light on and off. Thanks for your input.....

 

[dogfriend]

The PCM turns the light on directly.

I would look for a wiring problem preventing the light from turning on.

 

[rangerstx]

problem with MIL light not lighting

thanks for the input Dogfriend. If I can't find the wiiring problem soon I"ll just take it in to someone who might be able to find it quicker.

 

[410Fortune]

the MIL wire leaves the computer and goes directly to your instrument cluster.

The instrument cluster already has the - signal to make the circuit complete and light up the MIL.

With a test light you can test hte function of the PCM by tapping in to the MIL wire at the PCM 110 pin plug.

a 1985 Ranger with a 2.8L may not have had a MIL. Did you check that there is a bulb in the insrument cluster?

What I am getting at is my 1988 BII has the same dash as your 85 ranger.
Since my truck came with electric shift 4x4 Ford did not put a 4x4 bulb or low range bulb in the dashpot. The lights instead are in my 4x4 push buttons.
By simply adding a bulb to these two locations I now have lights in my dash for both of those positions. I wonder how much $$$$ they saved on those two light bulbs not being in the electric shift models?