Circuit Description
The speed sensors are variable reluctance devices that 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 that is mounted adjacent to a rotating ferrous member, such as a gear tooth. 2 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 m volts at low speed to 15 volts 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. Using 2 wire differential inputs at the TCM eliminates noise from other sources.
DTC P0717 is a type A DTC.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0717 Turbine Speed Sensor
Conditions for Running the DTC
| • | DTC P0721, P0722, P0731, P0732, P0733, P0734, P0735, and P0736 is not active. |
| • | The components are powered and ignition voltage is greater than 9.0 volts and less than 18 volts. |
| • | Engine speed is greater than 200 RPM and less than 7,500 RPM for 5 seconds. |
| • | The shift selector indicates a valid range selection except NEUTRAL. |
Conditions for Setting the DTC
DTC P0717 sets when the TCM detects one of the following conditions:
| • | An unrealistically large change in turbine speed |
| • | An unrealistically low turbine speed |
Action Taken When the DTC Sets
| • | The TCM illuminates the malfunction indicator lamp (MIL). |
| • | 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 selecting DRIVE again, the transmission will lock in NEUTRAL. |
| • | DTC P0717 is stored in TCM history. |
| • | The TCM freezes shift adapts. |
| • | The TCM inhibits torque converter clutch (TCC) engagement. |
Conditions for Clearing the DTC
A scan tool can clear the code from TCM history. The TCM automatically clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without failure.
Diagnostic Aids
| • | Inspect the wiring for poor electrical connections at the TCM. Inspect 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 condition. |
| • | If the condition is intermittent, connect the scan tool and select the speed sensor indicated by the code. If the signal is erratic, investigate and eliminate the following: |
| - | Intermittent wiring connection |
| - | Excessive vibration, such as driveline or engine torsionals |
| - | Irregular sensor gap, such as a loose sensor, a loose tone wheel or a damaged tone wheel |
| - | Inspect that the speed sensor wiring consists of twisted pairs at the rate of 12-16 twists per 300 mm (12 in). These twists must extend the entire length of the wiring harness to within at least 50 mm (2 in) of the speed sensor connector. |
Step | Action | Value | Yes | No |
|---|---|---|---|---|
Schematic Reference: Automatic Transmission Controls Schematics | ||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |
2 |
Important: Before clearing the DTC, use the scan tool in order to record the Freeze Frame and Failure Records for reference. The Clear Info function will erase the data. Is the voltage within the specified range? | 9-18 V | Go to Step 3 | Go to DTC P0562 for low voltage or DTC P0563 for high voltage |
3 |
Is the speed sensor resistance within the specified value? | 2,600 ohms @ 25°C (77°F) | Go to Diagnostic Aids | Go to Step 4 |
4 |
Is the speed sensor resistance within the specified value? | 2,600 ohms @ 25°C (77°F) | Go to Step 5 | Go to Step 6 |
5 | Test the turbine speed sensor circuit between the TCM and turbine speed sensor for an open or short to ground condition. Refer to Circuit Testing . Did you find and correct the condition? | -- | Go to Step 7 | -- |
6 |
Important: Do not rotate the speed sensor in the retaining bracket. Orientation is fixed, and if changed, may cause improper operation. Replace the turbine speed sensor. Refer to Speed Sensor Replacement . Did you complete the replacement? | -- | Go to Step 7 | -- |
7 | Perform the following procedure in order to verify the repair:
Has the test run and passed? | -- | Go to Step 8 | Go to Step 2 |
8 | With the scan tool, observe the stored information, capture info and DTC info. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK | |
