Full disclosure: I am a Ford technician. I am not a particularly good diagnostic tech though, and my role at my dealership doesn't require me to be (mobile service wizard of recalls and module configuration, yeeee haw.). Also, my Ranger has been looked at (and will be again) by a very skilled and trusted senior master Ford tech, who is currently scratching his head. The following is going to have some technical details (although not too many), but I'm curious if anyone has come across this issue before or if there are any other techs out there that have an alternative idea to what may be going on to give us some ideas.

2011 Ford Ranger Supercab
2wd
2.3L I4
5 speed manual M5OD trans

Several weeks ago, I was accelerating to get onto the freeway. It suddenly felt like someone turned the key off while I was driving. It was violent - I initially thought that my clutch had just let go and exploded. The dash lit up like a Christmas tree, I had limited power, the truck was jolting and shaking around. I pulled over and turned the key off - the radio was on, I'm not sure if the engine was already stalled or if I shut the engine down with the key. I tried to crank it... it cranked very very hard, but it started and it idled totally normally. I went to pull out, and within seconds... BAM. It happened again. This happened two more times. I got it started a fourth time, and it sat and idled. No malfunction indicators on the dash, just sitting there idling like nothing happened. I tried reverse, and it worked normally. I backed the whole way off of the ramp and turned around. I tried second... and it worked normally. Third did too. I got back home (about a mile) and tested it in my driveway. Guess what? First was fine now too. The truck was acting like nothing ever happened. The only lingering issue was the extremely hard starting. It sounds like the truck is hacking and coughing (more on this later). The next night I tried to do some diagnostics myself with my OEM Ford scan tool. No codes, no issues, no problems.... even though there still was one. So I got it towed to work and promoted the '83 back to daily driver status.

It went in right away for diag from the master tech. I figured it'd be a sensor or a frayed wire, something quick and in and out. Three days later... I couldn't be that lucky. So what was happening was that the voltage coming out of the ignition switch (note, not the key switch, but the electrical switch a bit down stream) was jumping from normal to 0 volts a few times a second. This explained the "coughing" starts.... the starter was basically having its light switch flipped on and off and on and off. New switch ordered and installed... still the same problem. Back to diag. So, the way the switch works is that turning the key to ignition sends it voltage, but the clutch safety switch being depressed sends a signal to the PCM to add the ground, and ouila. All these circuits were tested independently and found to be good. The clutch switch is supposedly good, the ignition switch is good, the wires connecting everything are good. The PCM itself had good ground... but the PCM was not supplying that signal to ground like it was supposed to. It was doing it in a flicked-light-switch fashion... so there was where that was coming from. Furthermore, the tech pulled the pin for that particular circuit (CDC12, for those curious) and manually grounded it against another spot. The truck then cranked and started completely normally. So, the technician "permanently temporarily" grounded that circuit to the stud on the firewall and circumvented the PCM. He tested the truck and was able to start it and drive it like normal. The clutch safety switch was circumvented so I was warned that it would try to start in gear, but that was fine for the time being.

I get my keys back and go to leave. The truck now cranks smoothly and properly.... but it will not start. I undo the ground and repin the connector back to normal, and it goes back to a coughing start, but it fires up and idles/drives normally (at least, a little bit. I assume it would eventually conk out again if I took it on a road trip). That ground connector has nothing to do with fuel or spark, by the way. It's at this point where it's just looking like a failed PCM. I use my parts connections and, sorry, order what appears to be the very final OEM PCM for the 2.3l/5spd in the entire country.

I wait for a week, and today, it finally showed up. PCM installs are something that I do often, so I launched into it with excitement. I repinned the connectors back to normal and got rid of the bonus ground. I followed through with the standard PMI/"suck-and-blow" procedure. It went fine. I did a PATS parameter reset so my keys would work again. It all went the way it should. I went to start it..... same exact problem. I even regrounded that wire and it went back to perfect crank, no start. No DTCs, no engine light, no indicators anything is wrong. The chances of me buying a PCM that has the exact same issue on the exact same circuit seem to be pretty small... so it almost can't be the PCM. I'd really not rather buy a third one to test that theory... they ain't cheap. And now it would be an aftermarket refurb anyway. It's scheduled for continued diagnostics next week with master techs again.

So, this is a shot in the dark, but has anyone had this issue? Are there any techs out there who have a hunch? I'd really like to get my truck back, and the disappointment of all the waiting and cost only to have it still sitting on the lot is really putting a damper on my weekend. On the plus side, I did just get a clean PA title for my '78 crew cab in the mail after having to sue somebody for it.... so I guess that's good news, but also it just means I'm justified to spend way more money on that too...

Any help or leads would be greatly appreciated!

 

There are a lot less Ranger fanatics on this part of the forum than there are bullnose and dentside guys where I normally hang out

Anyway, I have my truck back! I'm posting these results for posterity, in case anyone else ever has a similar issue. It took three weeks and calls to the Ford engineer hotline (who also didn't know). A last ditch effort was made and every single circuit related to the PCM was checked. As it turns out, Fuse 39 was blown. This 15-amp fuse provides power to an unspecified circuit in the PCM. As the tech told me, why a power circuit would cause a ground issue is unknown to him. We don't have access to any internal module schematics, so we don't know why those two circuits are related, but one little fuse (and a few big bills) later, the Ranger is back in the stable.

I am rationalizing all this to myself with the following theory: Fuses blow for a reason. Also, the issue was a ground issue from the PCM. Maybe, the old PCM developed an internal short and shorted that circuit to ground and blew the fuse. So, it wasn't a waste of money to put a new PCM in after all! That's what I'm gonna tell myself anyway I am probably gonna throw a few fuses in the glovebox though just in case, although the tech said he traced the whole circuit and didn't find any physical damage to the wiring. Another point to my PCM theory.

 

Glad you found it. How many miles on the Ranger?

 

It's only about to hit 130k miles. I bought it brand new when I was only 19, so it certainly has some sentimental value to me in addition to being a really solid all-around vehicle. I plan on keeping it as long as possible (and then even longer, maybe) so it was worth it to me to spend the time and money to get this rectified.

It certainly is still a head-scratcher even though we got it sorted, though. It is the equivalent of "I cut the power cord on my microwave. My microwave still works alright, but now my fridge won't turn on.''

 

I'm pretty sure this guy could tell you the cause....
https://www.youtube.com/@PineHollowAutoDiagnostics