hi i have a rough 93 ranger with 4.0 v/6 the pcm fried i repaired it im no expert but a good chance i got it right fried again no power to fuel pump or injector pulse have tested many things i think theres a short in the harness i cant jus keep sticking pcms in it so any ideas tips tricks wiring bad spots thanks in advance

 

Welcome to the forum

Very hard to "fry" a PCM, only has a 30amp fuse, make sure someone hasn't put in a larger fuse

Below is the two 4.0l PCM wiring diagrams, 1993/4 are the same
You can test wiring for 12v and ground at those pins on the 60-wire connector

All the sensors are 5volts or less so wouldn't "fry" anything, its possible a 12v wire is shorted to sensor wire, test for that, with connector off and key on all sensor wires should be 0 volts

Check alternator
If voltage regulator fails it can output more than 14.8volts which CAN fry electronics, or it can even send out high AC Volts

 

hi i know i dont seem to bright but raised on points coils etc thanks alot for the help and diagrams i have 12 volt to the injectors but there not firing i have spark but im guessing its in limp home mode thanks again

 

Nothing has changed too much as far as gasoline engines
I to grew up with distributors, points, single coils and carbs, they were a pain, lol
Only reason we had to know about them was because we ALWAYS had to adjust them
The newer electronic systems don't need much from us, so we never bothered/needed to learn about them

Things are much easier now, in my opinion

Gas engine still needs the 3 things it always did
Compression, above 120psi
Fuel
Spark, at the right time

You can still do 50/50 test, used since the 1890's, lol
Spray fuel into the engine
Try to start it
If it starts runs and dies then you have spark at the right time but no fuel flow
If it doesn't start then you have no spark(or no compression)
50/50 instant results

In 1993 the computer just does injectors, spark is done by EDIS-6 module, so separate systems
You should have a CEL(check engine light) in 1993
It should come on with key on and stay on, it means computer is powered up
As soon as you start cranking over the engine CEL should go OFF, that means computer is getting a good Timing Signal from EDIS-6 module so it will start opening injectors
If CEL doesn't go OFF then no injectors

If CEL doesn't come on then no power to computer