I stupidly disconnected the PCM connector with the battery connected. After reconnecting it, the engine would turn over but not start. What damage have I done and any recommendation as to how to recover.

 

Welcome to the forum

What year Ranger?

PCM 1994 and earlier is different than 1995 and up PCM
But there was no damage in either case

Disconnecting the PCM wiring harness usually requires a bit more work than just unplugging it, so I am sure something else is why its not starting
You can unplug it again and plug it back in just to make sure all pins are making a good connection

 

I must apologize. It is a 99 Mazda B2500. PCM is model XL5F-12A650-ARB. I had tried disconnecting the battery and grounding that terminal for a while and then reconnecting.it. Still no luck,

 

For 1999 you have a 104 wire EEC-V PCM, it runs BOTH spark and fuel, 1994 and earlier PCM just did fuel

There is actually only 1 "live wire" on it with key off, that's for the memory chip, which is erased when power is cut anyway, so you couldn't hurt the PCM by unplugging or plugging it in with battery connected

When you have a crank but no start the first thing to do is the 50/50 test
50/50 test
Spray fuel into the engine, gasoline, ether, carb/brake cleaner, ect.............what ever you have handy
Try to start
If it fires/starts, then you have good spark but no fuel from injectors
If it doesn't fire/start then you have no spark, (On a 2.5l there is also the chance the timing belt broke/slipped)
50/50 instant results on what to look at next


Couple of things to look and listen for
With Key on the CEL(check engine light) should come on, that means PCM has powered up, no CEL = no PCM
As soon as you crank the engine over CEL should go OFF, that means PCM is getting a good timing signal from Crank sensor as engine spins, no timing = no start

With key on you should HEAR the fuel pump in the gas tank HUMMMM, but just for 2 seconds
Repeat key off and on and listen, pump is not all that quiet, you can hear it in the cab if you listen for it
Fuel pump only runs for 2 seconds each time PCM is powered up, its a safety thing, doesn't hurt anything to power it off and on

On the 2.3l/2.5l Lima engines have a look at the cam's timing belt gear while someone cranks the engine, it should be spinning of course, if not the belt broke, cranking should also "sound funny", a lope to it because of compression being unequal with no valves opening and closing

And of course, is there Gas in the tank?
Its not insulting, just a fact that gas gets siphoned out of vehicles that sit and gas gauges do break
Chased my tail more than a few times on empty tank no starts, lol