Hello, this is my first time posting on any vehicle forum (though I lurk on quite a few). I ran into an issue that I could use a little guidance. I have done a lot of research and some diagnostics and I want to make sure I am not going in the wrong direction.

I have a 2008 Ford F150 Fx4 5.4 liter triton (oxford white) with a crew cab and towing package.

A few days ago I was driving down the road and all of a sudden the truck started a high-rev and then just cut out. I coasted to the side of the road and tried to restart the engine. While the engine was in idle and in park without the brake nor the accelerator pressed, the idle sounded normal. When pressing on the brake the RPMs spiked, then dropped, then spiked, then dropped, then the engine cut out. Again, the car was still in park. After starting again, a similar situation. I tried to put it into drive and as soon as it went into drive, the engine cut out immediately.

I did a code scan and saw the following codes; P0222, P2104, P0122, P060B, P2110. After a little digging around a few people recommended replacing the throttle body position sensor and possibly the throttle body injector. The throttle body injector is relatively new, I replaced it last year though I used the old position sensor when I replaced it (the new one did not come with a new position sensor). I pulled the injector just to be on the safe side. I checked it for any build up and there was a little, but for the most part, it was pretty clean. I purchased a new position sensor, put it on, and then reinstalled everything. Doing an engine check, the conditions were exactly the same as before, though the scan now shows P2107, P0122, P060B, and P2111.

I next started to check the wiring. I took the harness off of the position sensor and checked the voltage. I found the negative (wire 1), the 5+power (wire 4), and the signal wire (wire 3). I put the multi-meter negative on wire 1 and positive on wire 4 and turned on power (though not the engine) and I got back 0.14 volts. I then put the positive probe on wire 3 and got 0.16 volts. I checked both of these several times to make sure that the readings were consistent and within a hundredth of a point or two, they stayed consistent. I then changed the negative probe to the battery negative post and then did all the tests again and got the same results. Next, I plugged the harness back into the sensor and then put the probes in the back of the harness for each of the wires and performed the tests again and had the same results.

I have not checked the accelerator sensor though I have been told that this one rarely ever goes bad and when it does the voltage from the signal wire is normally zero (not sure if that is true that is just what a friend told me).

Some of the guides that I have looked at and videos I have watched have mentioned that if the 5+ power wire (wire 4) isn't close to 5 volts then the most likely issue is a bad PCM. I have been wondering about this for a while due to some other observances, but to be honest, I am not experienced enough to know for sure if I am jumping to conclusions or not. I am fairly technical and handy, I just lack some experience and background knowledge. Changing out the PCM is a bit of a pain due to the coding and the security with the keys and all of that, so I wanted to make sure that I have exhausted all my avenues before I jumped in that direction.

Any guidance would be much appreciated.

 

First off, is hard to tell how you are looking to the TPS connector to determine which one is wire 1 vs wire 4, or if you are following some diagram, so hopefully the figure helps.


with KOEOFF


C189 Pin 1 TPS2 = 1.2V (PCM/60) C175E
C189 Pin 2 VREF = 5V (PCM/66) C175E
C189 pin 3 GND = GND (PCM/59) C175E
C189 Pin 4 TPS1 = 4.1V (PCM/61) C175E

when HOT IDLE same values but TPS2 = 0.72V

If you don't have this readings at C189, then check right at the PCM connector C175E, I included the pin numbers for you to check.
If everything checks out then probably a bad sensor OR you need to re-calibrate the one. Check this video for recalibration

 

Thanks for the info. The thumbnail you provided is different from the one I found previously. I will check out what you sent tomorrow morning. Thanks again.

 

@99F150V6 I followed the guidance in the video to re-teach the PCM with the new position sensor. After running the idle for 15 minutes, I turned the engine off and then started the engine again. When I stepped on the brake pedal the RPMs did not spike like last time. I put it into drive and this time the engine did not automatically cut off. So far so good. I then tried to drive down the street. The car would move and the engine sounded clean though the accelerator did not do anything. It seemed to just move in idle. I could put the accelerator all the way to the floor and the speed did not change. I was able to put it into reverse and it drove fine in reverse. When I did the scan again, the codes that show up now are P2104, P0122 and P060B. I did not get a chance to check the voltages again, though things are looking like the throttle position sensor is OK and the PCM is most likely OK, I will try to test the voltages again tomorrow to be on the safe side. I am just wondering if the accelerator sensor might be the more likely cause.

 

For anyone who cares or has run into the same situation. After replacing the TPS and ACC sensors the issue continued. It took a while, but I finally got the right wiring diagrams and correct positioning of the PCM harness (there are two 70-pin harnesses on the PCM and I was told to look at the incorrect one, the correct one is the first on the left). I was also incorrectly told the wrong pin order (I finally found the pin-out diagram) and was able to confirm that the voltage coming from my PCM matches what is going to the TPS. I also was able to verify good continuity between the harness for the PCM and the harness for the TPS. It appears that the issue is with the PCM itself.