P0717
ALLISON AUTOMATIC TRANSMISSIONDTC P0717
Test 1-8
Test 9-10
Circuit Description for Allison Automatic Transmission
The speed sensors are variable reluctance devices which convert mechanical motion to an AC voltage. Each sensor consists of a wire coil wrapped around a pole piece that is adjacent to a permanent magnet. These elements are contained in a housing which is mounted adjacent to a rotating ferrous member (such as a gear tooth). Two signal wires extend from one end of the housing and an exposed end of the pole piece is at the opposite end of the housing. The permanent magnet produces lines of flux around the pole piece. As a ferrous object (such as a gear tooth) approaches and passes through the gap at the end of the pole piece, an AC voltage pulse is induced in the wire coil. The Transmission Control Module (TCM) calculates the frequency of these AC pulses and converts it to a speed value. The AC voltage generated varies from 150 mV at low speed to 15 V at high speed. The signal wires from the sensor are formed as twisted pairs to cancel magnetically induced fields. The cable is also shielded to protect from voltage-related fields. Noise from other sources is eliminated by using two-wire differential inputs at the TCM.
DTC P0717 is a type A DTC.
Conditions for Running the DTC
^ DTC 0716 is not active.
^ DTC P0721 and DTC P0722 are not active.
^ The components are powered and ignition voltage is less than 18 V and greater than 9 V.
^ Engine speed is less than 7500 RPM and greater than 200 RPM for 5 seconds.
^ The shift selector indicates a valid range selection.
Conditions for Setting the DTC
DTC P0717 sets when the TCM detects an input speed lower than 60 RPM for 1 second.
Action Taken When the DTC Sets
^ When failure occurs in a forward range and shifting is complete, the transmission remains in the current range. When failure occurs while in a forward range and the shift is in process, the transmission returns to the previous range, except in post-shift state, where the transmission will continue to the commanded range. When failure occurs in other conditions, the transmission shifts to 1st, 3rd, or 5th. While diagnostic response is active, if the shift selector is moved to NEUTRAL or REVERSE or re-selecting drive, then the transmission will lock in NEUTRAL.
^ DTC P0717 will be stored in the TCM history.
^ The TCM freezes shift adapts (DNA).
^ Illuminates the MIL when active.
^ TCM inhibits TCC engagement.
Conditions for Clearing the MIL/DTC
A scan tool can clear the code from the TCM history. The TCM automatically clears the DTC from the TCM history if the vehicle completes 40 warm-up cycles without failure.
Diagnostic Aids
^ Inspect the wiring for poor electrical connections at the TCM. Look for the following conditions:
- A bent terminal
- A backed-out terminal
- A damaged terminal
- Poor terminal tension
- A chafed wire
- A broken wire inside the insulation.
^ When diagnosing for an intermittent short or open, massage the wiring harness while watching the test equipment for a change.
^ You may have to drive the vehicle in order to experience a fault.
Test Description
The number(s) below refer to the step number(s) on the diagnostic table.
2. This step tests ignition voltage.
3. This step tests input speed sensor resistance.
4. This step tests the wiring harness for opens/shorts.
5. This step tests for proper AC voltage from the input speed sensor.