Hi everyone, for those that didn't see my previous thread I have an '06 Navigator that I've been chasing down a bunch of codes on. I've been dealing with P0330, P0059, P2197 that randomly showed up a few weeks after replacing everything behind the front timing cover and all drive accessories. I also cleaned the MAF and throttle body and the vehicle had been running fine for a couple weeks until I replaced the new power steering pump (it was defective) a couple weeks ago. After chasing down P0330, P0059, and P2197 I found that a pin on the PCM for knock sensor #2 was pushed in and slightly bent. I was able to straighten the PIN and pull it back out to where it needs to sit, and straightened out a few other pins that looked a little out of wack.

After connecting the PCM harness connectors to the PCM and removing them several times I was able to confirm that the pins were not getting bent or pushed back in again--everything seems to be lined up. But after firing the engine back up I'm now getting P2106, P0121, and P0122. The other codes seemed to have gone away with the PCM pins I adjusted, but now all of the sudden I'm getting these new codes (two of them pertaining to the TPS) and the infocenter in the dash says that the engine is running in fail safe mode.

I checked the connection to the TPS and the confirmed that the two Yellow/White wires on the connector are getting between 4.5 and 5 volts (4.8 to be exact) with the key in the ON position. I'm also getting a good ground, but don't have anyone here tonight to lend a hand to verify the operation of the TPS as the throttle blade is opened and closed. I did hook up two different scanners to my OBDII port and watched the PID for the throttle position, and I'm seeing the position stuck at 99.6% on both scanners.

The car idles higher than normal for a couple of seconds after a cold start, then pretty abruptly drops down to around 600 RPM and gets a very rough idle. The engine sputters and hesitates as I try to give it has while in Park.

So with the above said is this indicative of a TPS problem, throttle body problem, or perhaps both???

P0122 references a low input, but again, both yellow/white wires are getting 4.8 volts (I also checked this with the engine running) so I don't see it being an issue between the PCM pins and the wiring to the TPS connector.... but it's also strange how all of the other codes cleared up, and then these other 3 codes popped up in their place. Any help here would be greatly appreciated... I'm so ready to get back to enjoying driving this thing rather than spending all my time under the hood of it replacing parts and troubleshooting new problems lol.

 

All three codes are caused by an issue with the throttle position sensor's output as detected by the PCM.

Either the TPS issue is new (caused by your most recent work) and took precedence in the testing protocol (the other checks hadn't been done yet) or the repair work you did was successful but the TPS issue hadn't been tested yet due to the previous codes. It's all in how the engineer laid out the sequence of the component testing in the CCM routines in the PCM. Perhaps the protocol required that certain tests would not be run if a higher priority component failed its self-test.

You'll need the PCED and the EVTM to effectively troubleshoot this as there are a number of tests that are to be done to pinpoint the cause.

 

Thanks for the help Steve! I was honestly unaware that there was a sequence that depicts what codes would precede other codes... I always assumed any and all issues that had related DTC's would show up during a scan.

Well, I overlooked one important word in the P0121 and P0122 codes...... the word "pedal". I guess having never needed to troubleshoot a problem on a drive-by-wire car I just ignored the word "pedal" and assumed the code was referencing the TPS.

I didn't realize this until removing the TPS and testing the voltage going back to the PCM, and the voltage there checked out, so the TPS seems to have checked out.

I used FORScan to test some PID's also tonight and the PID for the accelerator pedal position sensor showed an error with the pedal fully released. Pressing the pedal down partially and holding it to the floor seems to register properly. So seems like the pedal sensor may be the problem.

I'm pretty disappointed that this seems to have gone bad out of nowhere as the car was just sitting in the driveway the past week while I replaced the power steering pump pulley and diagnosed these other codes. I guess I need to check the wires at the PCM before I go spending several hundreds of dollars on a replacement pedal position sensor since it seems you can only buy it as an assembly.

I have a PCM pinout that shows the accelerator position sensor wiring-- does anyone know where I can find info on testing the sensor wiring? I can't seem to find anything anywhere just yet. Thanks a bunch, and thanks again for your help Steve!

 

I highly recommend you buying the factory service manual, and the PCED for your vehicle. They can be found in paperback hard copies for 100+ bucks, or electronic ones on a DVD for 10 bucks on ebay. Those will give you all pinouts, wiring diagrams and testing procedures for everything, as well as how to disassemble and reassemble everything, including tourqe specs.

 

Thanks Skauber, I did order a DVD from Ebay yesterday after Steve's suggestion, but I'm just trying to get this truck back on the road. It's been sitting for almost another 2 weeks now while I have been trying to diagnose this, and probably won't see the DVD until after the weekend which is my only really good time to spend on this thing.

If anyone happens to have the info on testing the accelerator pedal position sensor and wouldn't mind sharing it I'd seriously appreciate it... definitely hurting to get this truck running again haha.

 

Your fault codes do not indicate an issue with the accelerator pedal position (APP) sensor. The APP sensor has its own set of DTCs.

The attached files should get you into the ball park.

Note: DTCs P0121 and P0122 both direct the technician to section DV in the PCED (attached). P2106 is an advisory DTC that simply indicates that the system is operating in its limp mode (FMEM) and that the technician is to diagnose the other DTCs first.

 

Steve, thanks so much for your help with proving those wiring diagrams and troubleshooting steps! I see what you guys are saying with how helpful these are-- I'm really looking forward to my DVD showing up now.

Here's what had me convinced it was a accelerator pedal position fault when I posted that update last night:



That was from my Torque app, and I'm pretty sure FORScan was also using the "throttle/pedal position" verbiage. That's when I Google'd "P0121 P0122 accelerator pedal position sensor" and found a bunch of people getting P0121 and/or P0122 and finding that replacing their accelerator pedal assembly was resolving their issue. Couldn't find anything on the Navigator/Expedition, but apparently lots of Excursion guys were finding this to be their problem.

With a new TPS I installed yesterday I took the following videos:



Weird how TPS1 isn't within range, according to the troubleshooting guide you shared, with throttle fully open nor closed.... and the TPS2 is only within range with the throttle closed. Again, this was on a new TPS, and you can see this in both videos. Not sure what "TP.OBDII - Throttle Position" PID is exactly, but it's definitely stuck at 99.61. Not sure if that means anything just yet. Also weird about the error on the accelerator pedal sensor PID when the pedal is fully released, which can be seen at the end of the second video.

I did plug the original TPS back in and rotated it, and when back-probing the sensor wiring at the sensor connector everything checked out. Smoothly went all the way up to 5v with the sensor rotated to the fully open position (not connected to the throttle body). I'll have to also back-probe those same wires at the PCM to make sure there's not a drop in voltage when I get home from work here later.

I'm going to follow through the rest of those troubleshooting steps you posted and will let you know what I come up with. Thanks once again!!!!