For 1990-2009 cars

## DTC P0502 Vehicle Speed Sensor (VSS) Circuit Low Input 2.4L Vin T

Automatic Transmission Components 2.4L
Automatic Transmission Controls Schematics 2.4L
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice

### Circuit Description

The Vehicle Speed Sensor (VSS) system is a pulse generator consisting of a speed sensor assembly, located in the case, and a toothed speed sensor rotor, which is pressed onto the final drive assembly. As the vehicle drives forward, the speed sensor rotor also rotates. This rotation produces a variable AC voltage signal in the pickup coil that is proportional to vehicle speed.

The VSS generates AC voltage varying from 0.5 volts at 100 RPM to more than 100 volts at 6000 RPM.

The PCM uses this signal to calculate vehicle speed and to develop the transmission shift pattern. Other systems also use VSS information:

• | TCC apply and release

• | Cruise control system

• | Fuel delivery systems

When the PCM detects an unrealistically low vehicle speed, with a high engine speed, while in drive gear range, then DTC P0502 sets. DTC P0502 is a type A DTC.

### Conditions for Setting the DTC

• | No MAP DTCs P0107 or P0108.

• | No TP DTCs P0122 or P0123.

• | The transmission is not in Park or Neutral.

• | The engine speed is more than 3200 RPM.

• | The throttle angle is 18-60%.

• | The MAP is 0-55 kPa (0-8 psi).

• | The output speed is less than 3 Km/h (2 mph) for 3 seconds.

### Action Taken When the DTC Sets

• | The PCM illuminates the Malfunction Indicator Lamp (MIL).

• | The transmission defaults to 3rd gear.

• | The PCM inhibits TCC operation.

### Conditions for Clearing the MIL/DTC

• | The PCM turns OFF the MIL after three consecutive trips without a failure reported.

• | A scan tool can clear the DTC from the PCM history. The PCM clears the DTC from the PCM history if the vehicle completes 40 warm-up cycles without a failure reported.

• | The PCM cancels the DTC default actions when the fault no longer exists and the ignition is OFF long enough in order to power down the PCM.

### Diagnostic Aids

• | Check for Electromagnetic Interference (EMI) in circuits 400 and 401. EMI may be induced if the harness is routed along the spark plug wires or alternator wires.

• | Inspect the wiring at the PCM, the Vehicle Speed Sensor (VSS) connector and all other circuit connecting points 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

- | Moisture intrusion

- | Corrosion

• | When diagnosing for an intermittent short or open, massage the wiring harness while watching the test equipment for a change.

• | Ensure that the VSS is securely tightened to the case extension.

### Test Description

The numbers below refer to the step numbers on the diagnostic table.

1. This step verifies that the PCM is receiving a signal from the vehicle speed sensor.

2. This step verifies that there are no opens in the circuitry, from the vehicle speed sensor, to the PCM connector.

3. This step performs a resistance test on the VSS circuits from the PCM connector.

#### DTC P0502 Vehicle Speed Sensor (VSS) Circuit Low Input (2.4L)

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Were you sent here from the Powertrain On-Board Diagnostic (OBD) System Check? | -- | Go to Step 2 | Go to Powertrain On Board Diagnostic (OBD) System Check
2 |

1. Install the Scan Tool .
2. With the engine OFF, turn the ignition switch to the RUN position.

Important: Before clearing the DTCs, use the scan tool in order to record the Freeze Frame and Failure Records for reference. Using the Clear Info function will erase the stored Freeze Frame and Failure Records from the PCM.

3. Record the DTC Freeze Frame and Failure Records then clear the DTCs.
4. Raise the vehicle and support lower control arms of the drive wheels.

Notice: Support the lower control arms in the normal horizontal position in order to avoid damage to the drive axles. Do not operate the vehicle in gear with the wheels hanging down at full travel.

5. Start and idle the engine.
6. Place the transmission in drive range.
7. Select Transmission Output Speed on the scan tool.

With drive wheels rotating, does Transmission Output Speed increase when wheel speed increases?

--

Go to Diagnostic Aids

Go to Step 3

3 |

1. Place the transmission in Neutral, or any drive gear. (It must not be in Park.)
2. Turn the ignition switch to the OFF position.
3. Disconnect the PCM connectors C1 (Blue) and C2 (Black).
4. Connect a J 39200 Digital Multimeter (DMM) to terminal 64 of the PCM connector C1 and terminal 61 of the PCM connector C2.
5. Select AC volts on the DMM.
6. Rotate the right drive wheel manually and rapidly, and observe the DMM.

Is the measured voltage greater than the specified value?

0.4 AC V

Go to Step 13

Go to Step 4

4 | Select Ohms on the DMM. Is the resistance between terminals 64 and 61 greater than the specified value? | 1864 ohms | Go to Step 5 | Go to Step 6
5 | Inspect circuits 400 and 401 for an open. Repair the circuits if necessary. Refer to General Electrical Diagnosis in Wiring Systems. Was a condition found and corrected? | -- | Go to Step 14 | Go to Step 10
6 | Does the DMM display a value less than the resistance specified? | 981 ohms | Go to Step 7 | Go to Step 8
7 | Inspect circuits 400 and 401 for a short together. Repair the circuits if necessary. Refer to General Electrical Diagnosis in Wiring Systems. Was a condition found and corrected? | -- | Go to Step 14 | Go to Step 10
8 |

1. Connect one lead of the DMM to a good ground.
2. Connect the other lead to terminal 64, then to terminal 61.

Is either resistance lower than the specified value?

50K ohms

Go to Step 9

Go to Step 11

9 | Inspect circuits 400 and 401 for a short to ground. Repair the circuits if necessary. Refer to General Electrical Diagnosis in Wiring Systems. Was a condition found and corrected? | -- | Go to Step 14 | Go to Step 10
10 | Remove the VSS and connect a DMM from terminal A to terminal B of the VSS. Is the measured resistance within the specified range? | 981-1864 ohms | Go to Step 11 | Go to Step 12
11 | Remove the VSS and inspect the Sensor Ring on the Final Drive Carrier Assembly for damage or misalignment. Was a condition found? | -- | Go to Unit Repair | Go to Diagnostic Aids
12 | Replace the Vehicle Speed Sensor. Refer to Vehicle Speed Sensor Replacement . Is the replacement complete? | -- | Go to Step 14 | --
13 | Replace the PCM. Refer to Powertrain Control Module Replacement/Programming in Engine Controls. Is the replacement complete? | -- | Go to Step 14 | --
14 | Perform the following procedure to verify your repair:

1. Use the scan tool to clear DTC information.
2. Drive the vehicle until the Transmission Output Speed is greater than 3 Km/h (2 mph) for 3 seconds.
3. Select Specific DTC.
4. Enter DTC P0502.

Has the test run and passed?

--

System OK

Go to Step 1

## DTC P0502 Vehicle Speed Sensor (VSS) Circuit Low Input 3.1L Vin M

Automatic Transmission Components 3.1L
Automatic Transmission Controls Schematics 3.1L
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice

### Circuit Description

The Vehicle Speed Sensor (VSS) system is a pulse generator consisting of a speed sensor assembly, located in the case, and a toothed speed sensor rotor, which is pressed onto the final drive assembly. As the vehicle drives forward, the speed sensor rotor also rotates. This rotation produces a variable AC voltage signal in the pickup coil that is proportional to vehicle speed.

The VSS generates AC voltage varying from 0.5 volts at 100 RPM to more than 100 volts at 6000 RPM.

The PCM uses this signal to calculate vehicle speed and to develop the transmission shift pattern. Other systems also use VSS information:

• | TCC apply and release

• | Cruise control system

• | Fuel delivery systems

When the PCM detects an unrealistically low vehicle speed, with a high engine speed, while in drive gear range, then DTC P0502 sets. DTC P0502 is a type A DTC.

### Conditions for Setting the DTC

• | No MAP DTCs P0107 or P0108.

• | No TP DTCs P0122 or P0123.

• | The transmission is not in Park or Neutral.

• | The engine speed is more than 2900 RPM.

• | The throttle angle is more than 15%.

• | The engine torque is 54-203 N·m (40-150 lb ft).

• | The output speed is less than 150 RPM for 2.5 seconds.

### Action Taken When the DTC Sets

• | The PCM illuminates the Malfunction Indicator Lamp (MIL).

• | The transmission defaults to 3rd gear.

• | The PCM inhibits TCC operation.

### Conditions for Clearing the MIL/DTC

• | The PCM turns OFF the MIL after three consecutive trips without a failure reported.

• | A scan tool can clear the DTC from the PCM history. The PCM clears the DTC from the PCM history if the vehicle completes 40 warm-up cycles without a failure reported.

• | The PCM cancels the DTC default actions when the fault no longer exists and the ignition is OFF long enough in order to power down the PCM.

### Diagnostic Aids

• | Check for Electromagnetic Interference (EMI) in circuits 400 and 401. EMI may be induced if the harness is routed along the spark plug wires or alternator wires.

• | Inspect the wiring at the PCM, the Vehicle Speed Sensor (VSS) connector and all other circuit connecting points 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

- | Moisture intrusion

- | Corrosion

• | When diagnosing for an intermittent short or open, massage the wiring harness while watching the test equipment for a change.

• | Ensure that the VSS is securely tightened to the case extension.

### Test Description

The numbers below refer to the step numbers on the diagnostic table.

1. This step verifies that the PCM is receiving a signal from the vehicle speed sensor.

2. This step verifies that there are no opens in the circuitry from the vehicle speed sensor to the PCM connector.

3. This step performs a resistance test on the VSS circuits from the PCM connector.

#### DTC P0502 Vehicle Speed Sensor (VSS) Circuit Low Input (3.1L)

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Were you sent here from the Powertrain On-Board Diagnostic (OBD) System Check? | -- | Go to Step 2 | Go to Powertrain On Board Diagnostic (OBD) System Check
2 |

1. Install the Scan Tool .
2. With the engine OFF, turn the ignition switch to the RUN position.

Important: Before clearing the DTCs, use the scan tool in order to record the Freeze Frame and Failure Records for reference. Using the Clear Info function will erase the stored Freeze Frame and Failure Records from the PCM.

3. Record the DTC Freeze Frame and Failure Records then clear the DTCs.
4. Raise the vehicle and support lower control arms of the drive wheels.

Notice: Support the lower control arms in the normal horizontal position in order to avoid damage to the drive axles. Do not operate the vehicle in gear with the wheels hanging down at full travel.

5. Start and idle the engine.
6. Place the transmission in drive range.
7. Select Transmission Output Speed on the scan tool.

With drive wheels rotating, does Transmission Output Speed increase when wheel speed increases?

--

Go to Diagnostic Aids

Go to Step 3

3 |

1. Place transmission in Neutral, or any drive gear. (It must not be in Park).
2. Turn the ignition switch to the OFF position.
3. Disconnect PCM connector C1 (Blue).
4. Connect a J 39200 Digital Multimeter (DMM) to terminals 64 and 65 of the PCM connector C1.
5. Select AC volts on the DMM.
6. Rotate the right drive wheel manually and rapidly, and observe the DMM.

Is the measured voltage greater than the specified value?

0.4 AC V

Go to Step 13

Go to Step 4

4 | Select Ohms on the DMM. Is the resistance between terminals 64 and 65 greater than the specified value? | 1864 ohms | Go to Step 5 | Go to Step 6
5 | Inspect circuits 400 and 401 for an open. Repair the circuits if necessary. Refer to General Electrical Diagnosis in Wiring Systems. Was a condition found and corrected? | -- | Go to Step 14 | Go to Step 10
6 | Does the DMM display a value less than the resistance specified? | 981 ohms | Go to Step 7 | Go to Step 8
7 | Inspect circuits 400 and 401 for a short together. Repair the circuits if necessary. Refer to General Electrical Diagnosis in Wiring Systems. Was a condition found and corrected? | -- | Go to Step 14 | Go to Step 10
8 |

1. Connect one lead of the DMM to a good ground.
2. Connect the other lead to terminal 64, then to terminal 65.

Is either resistance lower than the specified value?

50 K ohms

Go to Step 9

Go to Step 11

9 | Inspect circuits 400 and 401 for a short to ground. Repair the circuits if necessary. Refer to General Electrical Diagnosis in Wiring Systems. Was a condition found and corrected? | -- | Go to Step 14 | Go to Step 10
10 | Remove the VSS and connect a DMM from terminal A to terminal B of the VSS. Is the measured resistance within the specified range? | 981-1864 ohms | Go to Step 11 | Go to Step 12
11 | Remove the VSS and inspect the Sensor Ring on the Final Drive Carrier Assembly for damage or misalignment. Was a condition found? | -- | Go to Unit Repair | Go to Diagnostic Aids
12 | Replace the Vehicle Speed Sensor. Refer to Vehicle Speed Sensor Replacement . Is the replacement complete? | -- | Go to Step 14 | --
13 | Replace the PCM. Refer to Powertrain Control Module Replacement/Programming in Engine Controls. Is the replacement complete? | -- | Go to Step 14 | --
14 | Perform the following procedure, to verify your repair:

1. Use the scan tool to clear DTC information.
2. Drive the vehicle until the Transmission Output Speed is greater than 250 RPM for 2 seconds.
3. Select Specific DTC.
4. Enter DTC P0502.

Has the test run and passed?

--

System OK

Go to Step 1