I have a 94 4x4 ford ranger that has a check engine light on but no codes are stored. The truck runs great.

 

ODB-I - are you using a reader or counting flashes?

 

Welcome to the forun

It should have 111 code, that means system checks are OK

Or are you getting that but no other codes?

 

Yes and yes. Got a code 111 with light flashing, plus used code reader and it pulled no codes. My son did put headers on it, so I was wondering sence the O2 sensors are in a different spot if that would case it to come and if so how do you remedy the issue, Or could it be that the ECM needs replacing?

 

Yes and yes. Got a code 111 with light flashing, plus used code reader and it pulled no codes. My son did put headers on it, so I was wondering sence the O2 sensors are in a different spot if that would case it to come and if so how do you remedy the issue, Or could it be that the ECM needs replacing?

 

Good that you got the 1 1 1 as that indicates you did get into "code display" mode

No on the O2 sensors, as long as one is on the passenger side and one on the drivers side BEFORE any Cat converters they will work fine

So the CEL bulb gets 12v with key on, the Computer Grounds the bulb to make it light up, so if the wire from pin 17 on computer to instrument cluster B8 connection was shorted to ground anywhere then CEL would come on with key on and stay on

But it should NOT Flash when testing for codes because its Grounded full time
In the OBD1 connector in engine bay there should be two Pink/light green stripe wires connected to the same slot, thats the CEL Bulbs ground, from computer and to cluster
Shouldn't be a ground with key off, as far as I know, but also shouldn't be a ground after engine is started, well actually while engine is just turning over

There are 3 capacitors in the computer that can leak and cause odd ball issues, I just replaced the 3 in my 1994 4.0l but was having engine issues
Long shot would be to pull out the computer and have a look at the circuit board

 

I did both

 

I would agree with you on the short but when I start the truck it runs for about 3-5 seconds and then the light comes. Its so frustrating becouse ill fix something I think might have been the issue and all is good then the CIL will pop up like, Ha Ha got ya. I really won't to be sure its the ECM before forking out a lot of money for something that isn't even the problem, but I'm starting to wounder. Went to the junk yard to day to pick up a few items and noticed that all the 94s had the ECMs removed. Is this a common issue?

 

When PCM's get past 20-25 years old it becomes more common, but not at all "common" because of the number of them still on the road

 

Here is an update, I replaced the ECM and it fixed the issue. No more check engine light and truck runs great. Thanks for all the tips

 

Good stuff

Thanks for the update and THE FIX