4L60E, 4L65E and 4L70E P0716 and P0717: Input Speed Sensor No Signal, and the Real Fix

The truck ran fine before the rebuild. Now it comes back with a check engine light, a P0716 or P0717 stored, harsh or delayed shifts, and sometimes a converter that will not hold lockup. The scan tool shows input speed at zero, or bouncing around while the engine is clearly turning the turbine shaft. It looks like a big internal failure. Most of the time it is not.

The part for this fix

4L60E Output Speed Sensor 1993-2008 OEM 24232617

$26.99 · In stock

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On the late GM 4L60E family these two codes have a short list of causes, and the most common one is a wiring routing mistake made on the bench, not a worn-out part. Here is how to tell them apart before you pull the pan, and definitely before you pull the transmission.

First: does your unit even have an input speed sensor?

This is the step most people skip. The 4L60E did not always have an input speed sensor. According to ATSG's Wayne Colonna, the ISS came in during 2005 as a phased rollout, with the pump casting modified in July 2005 to accept the new harness, and full implementation arriving in model year 2006 — though he notes "there are some models that did not receive the ISS." If you are chasing P0716 or P0717 on an early unit, you are chasing a sensor the transmission does not have, and the fault is upstream.

Where the sensor lives matters too. Colonna describes it plainly: "The sensor is mounted on the pump, which reads rotor teeth that was added to the input (turbine) shaft." That is why an ISS problem is not a pan-drop repair.

The same change forced other parts to move. "To add rotor teeth to the shaft to be used to excite the speed sensor, the sealing rings on the shaft had to move," and "a modified stator shaft and stator shaft sleeve was done to accommodate changes made to the input shaft." That creates a real interchange trap, and Colonna's warning is blunt: "If dimensionally different pump covers and input shafts are mismatched, severe friction and geartrain damage will occur in a short period of time." He also notes that leaving the ISS plug off results in "a loss of converter charge pressure." If you are swapping a used unit or a used pump, match the pump cover, input shaft and harness as a set.

What the two codes actually mean

• P0716 — Transmission Input/Turbine Speed Sensor Circuit Range/Performance. The signal is present but wrong: erratic, implausible, or out of range. Engine-Codes lists the common causes as a faulty input shaft speed sensor, damaged wiring or connectors, low or contaminated fluid, a malfunctioning TCM, or internal transmission problems.
• P0717 — Input/Turbine Speed Sensor Circuit No Signal. The controller sees nothing at all. Listed causes are a faulty sensor, damaged wiring or connectors, and corrosion or poor connections at the sensor.

Because the controller uses turbine speed to calculate gear ratio and converter slip, a bad ISS signal corrupts the math that drives shift timing and pressure control. That is why the truck feels wrong even when nothing is mechanically slipping.

Diagnosis, in the order that saves the most labor

1. Check fluid level and condition first. Low or aerated fluid produces implausible speed data across the board and will chase you in circles.
2. Read live data in Drive with the brake applied. Compare input (turbine) speed to engine RPM. With the converter unlocked at idle the two should track with normal slip. Zero input speed while the engine is turning is P0717 territory; a signal that drops out or spikes points at P0716.
3. Go to the case connector before the sensor. The ISS low-reference circuit lands at terminal V of the transmission case connector. Inspect it for pushed-back terminals, corrosion, and fluid intrusion — a connector wicking fluid up the harness is a routine find on these.
4. Check the ground path. This is the one that stumps shops. The Transmission Digest Tech/Talk bulletin on this exact code pair notes that "one other known reason for these codes to be set has been a loss of an ISS ground circuit provided by the TCM. The loss of ground occurs inside the TCM." Their field repair: "Simply splice into circuit number 1984/1231 and ground it to earth. The circuit goes from terminal 45 at the TCM to terminal V at the case connector."
5. Only then suspect the sensor itself. A sensor that checks out cold and quits hot is real, but it is far down the list compared to wiring and ground.

The number one cause after a rebuild

If the codes showed up right after the unit was apart, the cause is usually mechanical damage to the sensor wiring inside the case. Transmission Digest documents it directly: "The input speed sensor wiring was not properly secured in its locating brackets on the back of the pump assembly. The wires were damaged by the spinning reverse input drum, which is close to the Input Speed Sensor wiring." Their correction is exactly as simple as it sounds: "Be sure to secure the Input Speed Sensor wiring harness."

A fresh rebuild with P0716 or P0717 is therefore very often a build error, not a parts failure. The reverse input drum passes close enough to the ISS lead that an unclipped wire gets shaved, and you will find the damage the moment the pump comes back out.

The fix, and which part you actually need

Once you have isolated it, the repair splits three ways:

• Damaged internal ISS lead or a failed sensor: for 2006–2013 4L70E applications we stock the OEM-numbered 4L70E input speed sensor, OEM 24244544, plus two other OEM part numbers for the same family in our transmission sensors collection. Read the number off the sensor you removed before ordering — GM used more than one on this family.
• Damaged case connector or external harness: the terminal V circuit is only as good as the connector it lands in. A 4L60E 20-pin case connector pigtail is the correct fix when the terminals are green or the pins are loose.
• Lost TCM-supplied ground: add the external ground on circuit 1984/1231 as described above, rather than replacing a control module that is otherwise healthy.

Replace while you are in there

If the pump has to come off to reach the ISS, the incremental cost of doing the rest is small compared to doing the job twice:

• Pump gasket, front pump seal and stator shaft sealing rings
• Input shaft sealing rings — they were relocated when the rotor teeth were added, so use the correct late-style rings and do not reuse the old ones
• Filter and pan gasket
• Case connector seal and internal harness, if fluid has been up the wires
• The 3-4 clutch pack and the input sprag if the unit has miles on it. See our write-up on 4L60E input sprag failure — the sprag sits directly behind the input drum you already have out.
• A full 4L70E Alto HEG super master rebuild kit if the fluid told you the unit is tired

Re-check endplay before you close it up. Any time the pump cover, input drum, shims or gear train parts are disturbed, the setting changes. Sonnax TASC Force specialist Randall Schroeder gives total endplay for the 4L60/E family as .005 to .036 in., and states his own preference of .020 to .025 in. He also flags that gear-set play measured between the output shaft and rear hub should be no more than .030 in., and that gasket choice shifts the reading: with a new pump cover gasket subtract .005 in., with no gasket add .005 in.

Cost and effort

Diagnosis is the cheap part: a fluid check, a live-data comparison, a case connector inspection and a ground test run well under an hour with a scan tool and a multimeter. The external repairs are DIY-plausible too. A case connector pigtail or the external ground splice on circuit 1984/1231 is a one-to-two hour job at moderate difficulty, provided you are comfortable depinning a connector and making a soldered, sealed splice.

The internal repair is a different animal. Reaching the pump-mounted ISS means the transmission comes out and the pump comes off — full R&R plus teardown, a multi-day job for most home shops. That is the practical reason to work the diagnosis in the order above: everything cheap comes first, and the expensive job is the last resort, not the first guess. It is also the reason to bundle the seals, filter and any tired clutch material into the same visit.

FAQ

Can I just clear the code and drive it? You can drive, but you should not leave it. The controller uses turbine speed for gear-ratio and converter-slip calculations, so a bad ISS signal degrades shift quality and pressure control. That means heat, and heat is what kills clutches.

My 2003 truck set an input speed sensor code. Does it need an ISS? Almost certainly not. The ISS was phased in during 2005 and fully implemented for 2006, so a 2003-build 4L60E does not have one. Look at the wiring, the vehicle speed sensor circuits and the controller instead.

I installed a used pump and now the unit is destroying itself. Why? ISS and pre-ISS pump covers, input shafts and stator shaft sleeves are not interchangeable, and ATSG warns that mismatching them causes severe friction and gear train damage in a short period of time. Match the set, and never leave the ISS plug disconnected — that costs you converter charge pressure.

Sources

• Transmission Digest Tech/Talk, "GM 4L70-E ISS DTC P0716 or P0717," October 8, 2020
• Wayne Colonna (ATSG), "4L60-E Input Speed Sensor Information," Vehicle Service Pros, January 1, 2020
• Randall Schroeder (Sonnax TASC Force), "All Work and No Play: Setting Endplay to Prevent 4L60/E Gear Train Failure," Transmission Digest, August 4, 2026
• Engine-Codes, "P0716 — Transmission Input/Turbine Speed Sensor Circuit Range/Performance"
• Engine-Codes, "P0717 — Input/Turbine Speed Sensor Circuit No Signal"

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