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For 1990-2009 cars only

Circuit Description

The automatic transmission output speed sensor is a variable reluctance magnetic pickup sensor and is located in the inside rear of the transmission case, above the control valve body and accumulator assembly. It is mounted in the case opposite the rear internal gear. The rear internal gear is splined to the transmission output shaft assembly.

The sensor consists of a permanent magnet surrounded by a coil of wire. As the output shaft and rear internal gear rotate, an alternating current (AC) is induced into the coil by the 'teeth' on the rear internal gear as they pass by the magnetic pickup.

The output of this speed sensor produces an AC voltage signal proportional to the rotational speed of the rear internal gear, which is rotating at vehicle speed.

Within the TCM, the AC voltage is converted to a 5 volt square wave form and this wave form is interpreted as the transmission output speed.

The TCM uses transmission input and output speeds to help determine line pressure, transmission shift patterns, TCC apply pressure, gear ratios and TCC slippage for diagnostic purposes.

If the TCM detects no vehicle speed when there is engine speed in a drive gear range, then DTC P0722 sets, which is a type 'B' DTC.

Conditions for Running the DTC

    • Ignition voltage is between 8.0 and 18.0 volts.
    • Engine speed is between 450 to 6,800 RPM for at least 5 seconds.
    • The following DTCs are not set:
       - P0716 or P0717 - Transmission Input Speed Sensor
       - P0723 - Transmission Output Speed Sensor
       - No engine torque DTCs.
       - No throttle system DTCs.
    • Vehicle speed is greater than 16 km/h.
    • Throttle position is greater than 12%.
    • Engine torque is between 70 and 450 N·m.
    • The transmission input speed is 1,500 to 6,800 RPM.

Conditions for Setting the DTC

The transmission output speed sensor signal is less than 100 RPM for 3 seconds.

Action Taken When the DTC Sets

    • The TCM requests the Powertrain Interface Module (PIM) to illuminate the Check Powertrain Malfunction Indicator Lamp (MIL) during the second consecutive trip in which the 'Conditions for Setting the DTC' have been met.
    • At the time of the first failure, the TCM records the operating conditions when the 'Conditions for Setting the DTC' are met. The TCM stores this information as a Failure Record.
    • At the time of the second failure, the ECM records the operating conditions when the 'Conditions for Setting the DTC' have been met. The ECM stores this information as a Freeze Frame.
    • TCM will determine the vehicle speed from the automatic transmission input speed sensor signal as well as the commanded gear ratio (signals to the TCM from the three shift solenoids).
    • The TCM also turns off the pressure control solenoid (causing maximum line pressure).
    • The TCM freezes the transmission adaptive learning function.
    • The TCM stores DTC P0722 into TCM history.

Conditions for Clearing the MIL/DTC

    • The PIM turns off the Check Powertrain MIL after the sixth consecutive drive trip in which the TCM does not send a Check Powertrain MIL illumination request.
    • Tech 2 can clear the DTC.
    • The TCM clears the DTC from its memory (history DTC) if the vehicle completes 40 warm-up cycles without a non-emission related DTC occurring.
    • The TCM cancels the default actions when the ignition is off long enough to power down the TCM.

Diagnostic Aids

Ensure that the transmission input speed sensor to transmission case bolt is correctly tightened.

Test Description

The number(s) below refer to the step number(s) on the diagnostic table.

3. Checks to determine if there is a short to voltage on the output speed sensor signal circuit.

4. Checks to determine if there is a short to ground on the output speed sensor signal circuit.

6. Verifies the circuit continuity from the TCM connector to, through, and from the output speed sensor.

Step

Action

Values

Yes

No

Schematic Reference: Automatic Transmission Controls Schematics

For information on testing wiring faults, refer to Wiring Systems.

1

Has the Diagnostic System Check - Automatic Transmission been completed?

--

Go to Step 2

Go to Diagnostic System Check - Automatic Transmission

2

  1. Connect Tech 2 to the DLC.
  2. Ignition ON, engine OFF.
  3. Record then clear stored DTCs.
  4. Start the engine and with Tech 2, scroll to Transmission Input Speed Sensor data list parameter.

Does the Tech 2 display output speed sensor above the specified value?

Greater than 100 rpm

Go to I Testing for Intermittent Conditions and Poor Connections

Go to Step 3

3

  1. Ignition OFF.
  2. Disconnect the transmission wiring harness connector from the TCM.
  3. Ignition ON.
  4. Using a digital voltmeter, measure the voltage between transmission wiring harness TCM connector A112-T68, terminal X1-1 and ground.

Is voltage reading less than the specified value?

Less than 0.3 volts

Go to Step 4

Go to Step 5

4

  1. Ignition OFF.
  2. Using a digital ohmmeter, measure the resistance between transmission wiring harness TCM connector A112-T68, terminal X1-1 and ground.

Is resistance greater than the specified value?

Greater than 500 kΩ

Go to Step 6

Go to Step 9

5

  1. Using a digital voltmeter, check the transmission wiring harness for a short to voltage condition between TCM connector A112-T68, terminal X1-1 and transmission wiring harness connector X121-X1, terminal X1-1.
  2. Also, check between the transmission wiring harness TCM connector A112-T68, terminal X1-2 and transmission wiring harness connector X121-X1, terminal X1-3.

Does either check indicate a short to voltage in the transmission wiring?

--

Repair short to voltage in relevant circuit.

Go to Step 13

Go to Step 11

6

Using a digital ohmmeter, measure the resistance between transmission wiring harness TCM connector A112-T68, terminals X1-1 and X1-2.

Is resistance within specified values?

325-485 Ω @ 20°C

385-575 Ω @ 70°C

Go to Step 10

If less than specified, go to Step 7. If greater than specified, go to Step 8.

7

  1. Using a digital ohmmeter, check the transmission wiring harness for an internal short circuit condition between TCM connector A112-T68, terminal X1-1 and transmission connector X121-X1, terminal X1-1.
  2. Also, check between the transmission wiring harness TCM connector A112-T68, terminal X1-2 and transmission wiring harness connector X121-X1, terminal X1-3.

Does either check indicate an internal short circuit in the transmission wiring?

--

Repair internal short circuit in relevant circuit.

Go to Step 13

Go to Step 11

8

  1. Using a digital ohmmeter, check the transmission wiring harness for an open circuit condition between transmission wiring harness TCM connector A112-T68, terminal X1-1 and transmission wiring harness connector X121-X1, terminal X1-1.
  2. Also, check between the transmission wiring harness TCM connector A112-T68, terminal X1-2 and transmission wiring harness connector X121-X1, terminal X1-3.

Does either check indicate an open circuit in the transmission wiring?

--

Repair open in relevant circuit.

Go to Step 13

Go to Step 11

9

  1. Using a digital ohmmeter, check the transmission wiring harness for a short to ground condition between TCM connector A112-T68, terminal X1-1 and transmission wiring harness connector X121-X1, terminal X1-1.
  2. Also, check between the transmission wiring harness TCM connector A112-T68, terminal X1-12 and transmission wiring harness connector X121-X1, terminal X1-3.

Does either check indicate a short to ground in the transmission wiring?

--

Repair short to ground in relevant circuit.

Go to Step 13

Go to Step 11

10

  1. Remove the transmission fluid pan. Refer to Transmission Fluid Pan and Filter Assembly Removal for the procedure.
  2. Inspect the transmission internal wiring harness for any sign of damage.

Is the transmission internal wiring harness OK?

--

Go to Step 11

--

11

  1. Remove the transmission input speed sensor. Refer to Input Speed Sensor Replacement for the procedure.
  2. Inspect the sensor for any sign of damage.
  3. Through the sensor mounting hole in the transmission case, inspect the reluctor teeth on the rear internal gear for any signs of damage.

Was any damage to components found?

--

For sensor damage, replace the damaged component. If rear internal gear damage is found, replace the transmission. Refer to Transmission Replacement

--

12

Replace the TCM. Refer to Transmission Control Module Replacement for replacement procedures.

Is the replacement complete?

--

Go to Step 13

--

13

Perform the following procedure to verify the repair:

  1. Using the Tech 2, select 'DTC' and then 'Clear DTC'.
  2. Drive vehicle in D5 Range and observe the Tech 2 Transmission Output Speed data parameter.

Verify that Tech 2 indicates an output speed sensor signal of greater than 500 RPM for more than 2 seconds.

Has the test run and passed?

--

System OK

Go to Step 2

When all diagnosis and repairs are completed, clear all DTCs and verify correct operation.