P0716 Automatic Trans Input Speed Sensor

Long time since I've gotten a DTC. This one tripped the SES today. I see three identical codes, the 3rd one tripping the light. I'm going to assume this code indicates a real problem, although I felt no difference in the cars operation. It came on unexpectedly during a 75 mph cruise, after some WOT activity, but not during.

Reading the shop manual, it says the code is an input speed sensor circuit - intermittent. The description is as follows:

The Automatic Transmission Input Sensor (A/T ISS) is a permanent magnet with a coil of wire wound around it. The A/T ISS mounts in the transmission case facing the drive sprocket of the input shaft. As then drive sprocket is driven by the turbine shaft, an AC signal is induced in the input speed sensor. Higher vehicle speeds induce a higher frequency and voltage at the sensor.

An air gap of .08-2.12 mm (.0032-.0084 in) must be maintained between the sensor and the drive sprocket to insure proper operation of the A/T ISS. The A/T ISS is used by the PCM in order the control line pressure, TCC apply & release, and transmission shift patterns. This sensor is also used to calculate the appropriate gear ratios and TCC slippage.

This diagnostic indicates stuck, erratic, or intermittent values, indicating poor performance of the system.

if the PCM detects an unrealistically large change in data from the A/T Input Speed Sensor, in a short period of time, then the DTC P0716 sets. DTC P0716 is a Type B DTC.

I haven't started diagnostics yet, but does anyone have experience with this code? Is the ISS and wiring accessible from outside the transmission?

What is a "Type B" DTC?

The DTC default action in the manual says "Disable shift adapts". What does this mean?

Thx in advance for help!

DTC Types =
Type A - Emission related, turns MIL ON after the first failure
Type B - Emission related, turns MIL ON after two consecutive trips with failure
Type D - Non-Emission related, no lamps

The DTC default action "Disable shift adapts" means that is the action the PCM and trans are taking in relation to this fault.
It is Disabling the shift adapts. Do not have any info on the normal operation of "shift adapting"...yet.

AA Wrote:
I haven't started diagnostics yet, but does anyone have experience with this code? Is the ISS and wiring accessible from outside the transmission?
Look at page 7-21; it appears it's available in the valve body. At first read it sounded like it was deep in the bowels of the trans.

Also look at page 7-24 for a view of the wiring harness connector. You can always check if connector is clean and contacts look good.

Did you see one of the conditions for setting the DTC.
"The input speed changes by greater than 1300 RPM in .08 seconds."

Just how fast or should I say abrupt changes in speed were you practicing.???

Easy to change RPM that much on a downshift at 65 mph, which I did twice yesterday. But .08 secs is pretty darn abrupt, imo.

Anyway, three trips later, no codes, and the SES went out. I'm not going to worry about it unless I see the light again. Thanks for the replies, Rick.

I have experience with it. Made me cringe seeing you post the code.

The input speed sensor is a stationary sensor that reads a gap in a wheel that sits on the driven gear. The wheel is held to the driven gear by 3 pins (frequently referred to as rivets). The three pins simply push into holes on the gear and is held to the gear by a busing on top of it being up against the channel plate (IIRC it's channel plate and not the VB, either way..it's up against something)

If the pins loosen up or break, this is commonly when you will get this code. Another potential time to get his code is if the chains stretch and are about to snap. (Buddy had that one).

The FSM will give you info about checking the wiring and the sensor going bad because in the normal transmission on the average unmodded car those are the normal failures. I've yet to have a normal failure and one day look forward to it.

The ISS reluctor wheel (after the break)


Challen plate from reluctor coming loose

Good info, Bill. Thanks. So being that my transmission was rebuilt about 38k miles ago, would this be something they should have looked at or replaced?

As of this morning 5 trips (one with full WOT run to 90 mph) and no more DTCs. Does this seem like something that would be random, coming and going from time to time?

What is the risk of running the car with this component failing. Does it progressively get worse and worse until... (?) Or does it just fail all of a sudden? What are the symptoms? The car drives and shifts like nothing's wrong.

During a rebuild the meticulous guy would check to ensure the three pins are not loose and replace the reluctor if needed. However most guys probably wouldn't check it closely. With us spinning higher rpms and things of that nature, this is one of those parts that can be more prone to failure.

Im my car the code doesn't illuminate the MIL, I was unaware of an issue until I heard what sounded like a bunch or marbles rolling around. Scared the crap out of me, meanwhile the car ran and drove fine.

The end result that you see in the second picture is that the channel plate was nearly worn through. From the time I heard the marble sound to the time I pulled the trans, there was maybe 30-50 miles put on it.

As well, my experience with it may not be your problem. A sensor can fail, wiring can have a problem etc etc etc.

Bill, thanks again. In your opinion, how similar is this 'marbles-in-a-can' sound to a bad SC coupler?

AA wrote:

Bill, thanks again. In your opinion, how similar is this 'marbles-in-a-can' sound to a bad SC coupler?

Did you ask this question because you hear what sounds like a bad coupler possibly.?
I'd hate to hear you have to do a teardown of the trans for this reluctor ring.

Well, I've had the code come back about 4 times, usually about every week or two, it will trip the SES and then shut off after 3 trips. I've gone as long as three weeks of everyday driving without seeing the SES, and it doesn't seem to be getting any more frequent.

I do hear a very faint grinding sound like Bill described, but it sounds exactly like a bad coupler. Coupler is tight, so this may be it. Right now I can't rip out the trans just for this. The car shifts and drives perfectly. I'm going to try and ride out the winter, see what happens.

Bill, if I eventually get the transmission out, how dificult is the job of replacing the reluctor ring?