DTC P0503 Vehicle Speed Sensor (VSS) Circuit Intermittent 2.2L
Circuit Description
The Vehicle Speed Sensor Assembly (VSS Assy.) provides vehicle speed information to the Powertrain Control Module (PCM). The VSS Assy. is a Permanent Magnet (PM) generator. The PM generator produces a pulsing AC voltage as rotor teeth on the transmission output shaft pass through the sensor's magnetic field. The AC voltage level and the number of pulses increase as the speed of the vehicle increases. The output voltage varies from a minimum of 0.5 volts AC at 100 RPM to more than 100 volts at 8000 RPM. The PCM converts the pulsing voltage to vehicle speed. The PCM uses the vehicle speed signal to determine shift timing and Torque Converter Clutch (TCC) scheduling.
When the PCM detects an unrealistically large drop in vehicle speed, then DTC P0503 sets. DTC P0503 is a type B DTC.
Conditions for Setting the DTC
DTC P0503 sets if the following conditions occur two consecutive times:
| • | No TFP Val. Position Sw. DTC P1810. |
| • | The time since the last gear range change is greater than 6 seconds. |
| • | The engine speed is greater than 450 RPM for 5 seconds. |
| • | Not in fuel cutoff. |
| • | Transmission output speed rise does not exceed 600 RPM within 6 seconds. |
| • | The transmission output speed drop is greater than 1300 RPM for 3 seconds when not in Park/Neutral. |
Action Taken When the DTC Sets
| • | The PCM illuminates the Malfunction Indicator Lamp (MIL). |
| • | The PCM commands a soft landing to second gear when the engine speed is below 2500 RPM. |
| • | The PCM commands maximum line pressure. |
| • | The PCM inhibits TCC engagement. |
| • | The PCM freezes shift adapts from being updated. |
| • | The PCM inhibits 4th gear if the transmission is in hot mode. |
| • | DTC P0503 stores in PCM history. |
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
| • | 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 condition, massage the wiring harness while watching the test equipment for a change. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | ||
2 |
Important: Before clearing the DTC(s), 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. Does the Transmission OSS drop or fluctuate more than the specified value? | 1300 RPM | Go to Diagnostic Aids | |
Is the resistance within the specified range? | 1470-2820 ohms | |||
4 | Measure the resistance from terminal C1-63 to ground. Is the resistance greater than the specified value? | 50 K ohms | ||
Is the voltage greater than the specified value? | 0.5 volts | |||
6 |
Is the resistance within the specified range? | 1470-2820 ohms | ||
7 | Inspect circuits 821 (PPL/WHT) and 822 (LT GRN/BLK) for a short to ground. Repair the circuits if necessary. Refer to General Electrical Diagnosis Procedures. Did you find a short to ground condition? | -- | Go to Diagnostic Aids | |
8 | Inspect circuit 821 (PPL/WHT) and circuit 822 (LT GRN/BLK) for an open. Repair the circuits if necessary. Refer to General Electrical Diagnosis Procedures. Did you find an open condition? | -- | Go to Diagnostic Aids | |
9 |
Did you find a damaged condition? | -- | ||
10 | Replace the VSS Assy. Refer to Vehicle Speed Sensor Replacement. Is the replacement complete? | -- | -- | |
11 | Replace the PCM. Refer to PCM Replacement/Programming . Is the replacement complete? | -- | -- | |
12 | In order to verify your repair, perform the following procedure:
Has the test run and passed? | -- | System OK |
DTC P0503 Vehicle Speed Sensor (VSS) Circuit Intermittent 4.3L
Circuit Description
The Vehicle Speed Sensor Assembly (VSS Assy.) provides vehicle speed information to the Vehicle Control Module (VCM). The VSS Assy. is a Permanent Magnet (PM) generator. The PM generator produces a pulsing AC voltage as rotor teeth on the transmission output shaft pass through the sensor's magnetic field. The AC voltage level and the number of pulses increase as the speed of the vehicle increases. The output voltage varies from a minimum of 0.5 volts AC at 100 RPM to more than 100 volts at 8000 RPM. The VCM converts the pulsing voltage to vehicle speed. The VCM uses the vehicle speed signal to determine shift timing and Torque Converter Clutch (TCC) scheduling.
When the VCM detects an unrealistically large drop in vehicle speed, then DTC P0503 sets. DTC P0503 is a type B DTC.
Conditions for Setting the DTC
DTC P0503 sets if the following conditions occur two consecutive times:
| • | No TFP Val. Position Sw. DTC P1810. |
| • | The engine speed is greater than 450 RPM for 5 seconds. |
| • | Not in fuel cutoff. |
| • | The time since the last gear range change is greater than 6 seconds. |
| • | The transmission output speed rise does not exceed 600 RPM within 6 seconds. |
| • | The transmission output speed drops by greater than 1300 RPM for 3 seconds when not in Park/Neutral. |
Action Taken When the DTC Sets
| • | The VCM illuminates the Malfunction Indicator Lamp (MIL). |
| • | The VCM commands second gear only. |
| • | The VCM commands maximum line pressure. |
| • | The VCM freezes shift adapts from being updated. |
| • | The VCM inhibits TCC engagement. |
| • | DTC P0503 stores in VCM history. |
Conditions for Clearing the MIL/DTC
| • | The VCM turns OFF the MIL after three consecutive trips without a failure reported. |
| • | A scan tool can clear the DTC from the VCM history. The VCM clears the DTC from the VCM history if the vehicle completes 40 warm-up cycles without a failure reported. |
| • | The VCM cancels the DTC default actions when the fault no longer exists and the ignition is OFF long enough in order to power down the VCM. |
Diagnostic Aids
| • | Inspect the wiring at the VCM, 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 condition, massage the wiring harness while watching the test equipment for a change. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step tests the VSS Assy. circuit.
-
This step tests the integrity of the VSS Assy.
-
This step tests the 5-volt and ground circuit of the VCM.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | ||
2 |
Important: Before clearing the DTC(s), 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 VCM. Does the Transmission OSS drop or fluctuate more than the specified value? | 1300 RPM | Go to Diagnostic Aids | |
Is the resistance within the specified range? | 1470-2820 ohms | |||
4 | Measure the resistance between terminal C1-30 and ground. Is the resistance greater than the specified value? | 50 K ohms | ||
Is the voltage greater than the specified value? | 0.5 volts | |||
6 |
Refer to General Electrical Diagnosis Procedures. Did you find an open condition? | -- | ||
7 |
Refer to General Electrical Diagnosis Procedures. Did you find a short to ground condition? | -- | Go to Diagnostic Aids | |
Is the voltage within the specified range? | 4.0-5.1 volts | |||
9 |
Did you find a damaged condition? | -- | ||
10 | Replace the VSS Assy. Refer to Vehicle Speed Sensor Replacement. Is the replacement complete? | -- | -- | |
11 | Was the voltage measured in step 8 less than the voltage in the value column? | 4.0 volts | ||
12 | Was the voltage measured in step 8 greater than the voltage in the value column? | 5.1 volts | -- | |
13 | Repair the short to B+ in circuit 821 (PPL/WHT). Refer to General Electrical Diagnosis Procedures. Is the repair complete? | -- | -- | |
14 | Replace the VCM. Refer to VCM Replacement/Programming . Is the replacement complete? | -- | -- | |
15 | In order to verify your repair, perform the following procedure:
Has the test run and passed? | -- | System OK |
