Josh.S

1999 Ford F150 5.4 4R70w Trans. Transmission was remanufactured a year ago with no following issues. Ov light started flashing with shifting problems. Received code P1715 Shift Solenoid B Inductive Signature. Replaced Shift Solenoid. Performed drive cycle and received P1714 Shift Solenoid A Inductive Signature. Code P1715 is no longer present. Replaced Shift Solenoid again thinking it could be a malfunction in the new part. Did not fix code P1714. Erased codes and performed drive cycles 5 times and had the same code every time. Recommendations for fixing this code was replacing shift solenoid or bad wiring or connection. Removed Harness and performed a visual inspection, checked resistance and tested for continuity. No issues with wiring or connectors. Performed continuity and resistance test on internal hard harness and all checked out. Truck shifts through all gears very smooth even at fast acceleration and high speed. The only 2 hesitation's I can feel is when coming out of overdrive to 4th gear and when coming to a complete stop. When I'm on the highway at 60 to 65 mph in overdrive and I let off the gas, it immediately shifts back to 4th when it should not be shifting out of overdrive yet. I know that because you can feel the truck slow down like you're hitting the brakes but its due to it shifting down to early and when I come to a complete stop, my RPM's stay high for about 7 seconds before returning to normal resting RPM's. I am very mechanically inclined, and I am stumped at this point. Things I have done, replaced shift solenoid and case connector, inspected and tested all wiring and connections which checked out good. Performed multiple drive cycles with code P1714 showing back up. Things I have not done, I have not replaced internal hard harness, input or output speed sensor, (EPC) Electronic Pressure Control solenoid or the (TCC) Torque Converter Clutch Solenoid. Only thing I can think at this time is the PCM, but I believe that I would have more problems than what I am experiencing at the moment. Thanks for taking the time to read.

BareBonesXL

The problem and the code.

pontisteve

I know this is pretty old thread now, but I'm guessing you are not going to find much information on your problem, and I think I might have some insight.

This is just how I think it works. I don't know for a fact. Anyway, any time you turn on a solenoid, which is basically an electromagnet, you build an electromagnetic field. When you turn that solenoid off, the electromagnetic field collapses in on itself, and creates a voltage spike. FYI, this is exactly how the primary side of an ignition coil works, and builds spark.

So while you are giving a solenoid like the shift solenoid, TCC solenoid, etc 12v all the time (when the key is on) on one side of the solenoid, the PCM provides a ground to the other side of the solenoid when it wants to turn that solenoid on. When the PCM quits grounding the solenoid, the solenoid turns off. But also, the electromagnetic field collapses at this point, creating a large voltage spike. For example, a 12 volt solenoid might spike up to 100 volts briefly when you shut it off. You can't see this with a voltmeter, it's too fast. But if you use an oscilloscope on the control wire (ground wire from PCM to solenoid), the scope is fast enough to see this spike in voltage. The spike probably lasts just a few thousandths of a second.

The PCM is also fast, and it can see this voltage spike too. You won't see this spike in scan data, because the data rate of a scantool is too slow, but the PCM sees it.

It's my belief that the diagnostic system in the PCM is looking at this voltage spike, expecting it to occur when the PCM shuts off the solenoids in the transmission. If this voltage spike doesn't occur, it's because there was not a large electromagnetic field in the first place, to collapse and generate the spike. So the PCM watches for this spike, and if it doesn't occur, the PCM knows there is an issue with this solenoid. That issue might be a lack of power (bad tranny fuse), a lack of ground (the driver in the PCM isn't grounding the circuit to turn it on), bad solenoid windings, or bad wiring from fuse to solenoid or from solenoid to PCM.

Bottom line: If for whatever reason that solenoid doesn't come on correct, and then create that spike when it is shut off, an inductive signature code will set. There seem to be inductive signature codes for Shift Solenoids 1 and 2, and for the Torque Converter Clutch solenoid. At least on a 99-03 F150. I know this because I am an EFI tuner, and I'm looking at the calibration. There are switches in the calibration that would allow me to turn these 3 inductive signature checks, and presumably the codes that go with them. The codes related to inductive signatures appear to be P1636, P1714, P1715, and P1740 from what I can tell. I'm not 100% on that, but any code mentioning "inductive signature".

I think if you are getting one of these codes, there is probably a problem with the solenoid, the wiring, or the 12v power source (fuse). It's also possible the problem lies within the PCM driver (not providing a good enough ground), the PCM grounds, or even just in the brand of solenoid you used (a non-Ford solenoid).

If all else fails, I can turn those inductive signature tests off in the PCM calibration.