P0503

P0503 - VEHICLE SPEED SENSOR (VSS) CIRCUIT INTERMITTENT (L81)









The Output Speed Sensor (OSS) produces an AC voltage of different amplitude and frequency depending on the velocity of the output shaft. The OSS produces the signal from 16 evenly spaced machined notches on the transaxle final drive assembly. The OSS produces a readable AC voltage signal when vehicle speed is above 5 km/h (3 mph). This OSS signal is sent to the TCM, which is used to determine the velocity of the output shaft. DTC P0503 sets when the TCM detects a dropout in the OSS signal for a certain length of time while the vehicle is moving.

DTC PARAMETERS
DTC P0503 will set if TRANSMISSION OHS signal drops greater than 600 RPM instantaneously when:
- Time since gear selector has been moved is greater than 6 seconds.
- Engine run time is greater than 5 seconds when engine speed is between 500 RPM and fuel cutoff.
- No ISS or TFP DTCs have been set.
- Transmission OSS does not increase by more than 300 rpm within a 100 ms time period for more than 2 seconds.
- Engine torque is between 100 and 150 Nm (74 and 110 ft. lbs.).
- Transmission ISS does not increase by more than 500 rpm within a 100 ms time period for more than 2 seconds.
- TFT range is not equal to Park or Neutral.

DTC P0503 diagnostic runs continuously once the above conditions have been met.
P0503 is a type B DTC.

DIAGNOSTIC AIDS
If DTC P0502 is also set, diagnose that DTC first.
To locate this intermittent problem, use Scan tool to monitor TRANSMISSION OSS with vehicle raised and drive wheels moving greater than 5 km/h (3 mph). Parameter will drop out if a fault occurs.
DTC P0503 can set if a direct or intermittent short to voltage on circuit 400 occurs; an intermittent open occurs anywhere in the circuit or an intermittent short ground in circuit 400 occurs.
Inspect TRANSMISSION OSS and differential carrier reluctor wheel teeth for damage. If the PCM does not receive an OSS signal or if DTC P0503 is active, it will command maximum main line pressure to the transaxle.
If the PCM does not receive a TRANSMISSION OSS signal, it will calculate vehicle speed based on engine speed, input shaft speed and commanded gear. The speedometer will still be inoperative, however.
Output Speed Sensor resistance: 1530 - 1870 ohms.