I have a 98 ford ranger 2.5l, I will be driving down the road and no matter what temp engine load or anything it will stall and mid stall the check engine light will flash a few times, but then when it is stopped and I turn the key to the off position, then back to the on position the check engine light will not come on, which means the pcm isn’t getting power and the truck won’t start for about an hour, but while the truck is on the on position, and I shake the truck a little bit the engine light will flash at random, my obd ll shows one code and it’s the to lean code, I’m at a loss, I’ve replaced coil pack, battery, crank and cam sensors, new pcm, I’ve took the whole wiring harness out and cleaned it and all the grounds, new ignition switch, new relays, fuses all good, one of my o2 sensors is faulty and I get a code for that sometimes but I don’t think that is the issue, ive spent a lot of money please help me

 

Welcome to the forum

Yes, reads like the PCM is losing 12volts or ground which will shut down the PCM and engine will stall

Reads like you have replaced a lot of stuff so most likely issue is a wiring problem or engine bay fuse box

CEL on means PCM is powered up
CEL off means PCM is off

There is just the 1 wire from ignition switch to engine bay fuse box that activates the PCM relay, and that turns on the PCM(CEL on) and powers injectors and fuel system
If you pull out the PCM relay and test its slots, key off
You should have 1 slot with 12volts all the time from PCM fuse
And 1 slot that's a full time ground
Key on
Now there should be another slot with 12volts, from ignition switch

If the ground here is intermittent then relay will shut off, needs full time good ground at this relay

It's a pain to remove engine bay fuse box to open it up on the under side to have a look at the wiring but I would say thats the next step

 

Okay I will check that today and get back with you later tonight

 

Okay so I check both grounds, one lit up bright with the key off, then both lit up with key on and they lit up bright, I checked one positive, and it was bright and the other positive wasn’t, with the truck on or off the not so bright positive stayed on either way so I’m not sure how to go about this

 

Looks like a Mini relay, so slots are these: https://www.gtsparkplugs.com/images/...iring-840x.jpg

Slots 30 and 87 are the Load terminals
One will be 12volts from PCM Fuse
Other will be 12v OUT to PCM(and other stuff)

85 and 86 are the Relay activation terminals
One will be a full time ground(in this case)
Other will be Key ON 12volts


Other relays in the box are Micro type, just FYI: https://www.gtsparkplugs.com/images/...lay-wiring.jpg
Same terminals do the same job just different lay out

On 4 slot relays 30 and 87 do not have an assignment, i.e. 30 doesn't have to be the 12volts and 87 doesn't have to be the "device" being powered, when relay is activated the two are connected together so 12volts passes thru

Same for 85 and 86, either can be the ground or the 12volts, but there must be both or relay will not activate

 

Okay so I took the wiring harness apart and I found a corroded pin and I cleaned it out it all back together and the light was bright as it should be when I tested it, and I drove it around for about 10 minutes and then the truck did the same thing, it stalled bumped back to life then stalled right after, and the whole time the check engine light was flashing im very lost

 

CEL flashes if it detects misfires, or a computer fault, can you get any codes from the computer?

 

These are all the codes I get, the only reason my fuel pump is high is because I ran the fuel pump to a switch so I could see if that was the issue

 

Okay so today I decided to mess around with some stuff and I found something interesting so when I sit or shake the truck you can here the pcm relay flicking on and off, and this is a brand new relay

 

No codes for the stall means PCM is shutting off so can't set a code for that, lol

Good find with PCM relay "clicking"
You have the diagram of the relay slots
For the relay to "click" on and off with key on, then 85 and 86 are the issue(ignore 30 and 87)
One will be 12volts with key on
Hook test light to Battery Negative and see which one lights it up, then shake the truck like you did before to see if test light flickers
If not
Then hook test light up to battery Positive and put it in the other slot, the full time ground slot, light should come on, shake the truck again

You are trying to find out what is being lost on that relay, the ground or the 12volts from the key