DTC P0503. Saturn L300/LW300 2003

For 1990-2009 cars only

Makes 🢒 Saturn 🢒 2003 🢒 L300/LW300 🢒 DTC 🢒 DTC P0503

DTC P0503 2.2L (L61)

Master Electrical Component List
Automatic Transmission Controls Schematics 2.2L
OBD II Symbol Description Notice

Circuit Description

The automatic transmission output shaft speed sensor (AT OSS) provides vehicle speed information to the PCM. The AT OSS is a permanent magnet generator mounted to the transmission case. The AT OSS produces an AC voltage as the transmission speed sensor rotor teeth pass through the magnetic field of the sensor. The AC voltage level increases as the speed of the vehicle increases. The PCM converts the AC voltage into a digital signal. The PCM uses the vehicle speed signal to determine shift timing, torque converter clutch (TCC) apply, TCC release, and gear ratio calculations.

When the PCM detects a loss of vehicle speed while the vehicle is in motion, then DTC P0503 sets. DTC P0503 is a type B DTC.

Conditions for Running the DTC

•	No MAP DTCs P0107 or P0108.

•	The engine is running.

•	An increase in output speed of 250 RPM or greater has not occurred for greater than 5 seconds.

•	The engine torque is greater than 68 N·m (50 lb ft).

Conditions for Setting the DTC

Output speed drops greater than 1,200 RPM for 3 seconds.

Action Taken When the DTC Sets

•	The PCM illuminates the malfunction indicator lamp (MIL) during the second consecutive trip in which the Conditions for Setting the DTC are met.

•	The PCM commands maximum line pressure.

•	The PCM freezes transmission adaptive functions.

•	The PCM calculates output speed from input speed, engine speed, and commanded gear.

•	The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Freeze Frame and Failure Records.

•	The PCM stores DTC P0503 in PCM history during the second consecutive trip in which the Conditions for Setting the DTC are met.

Conditions for Clearing the MIL/DTC

•	The PCM turns OFF the MIL during the third consecutive trip in which the diagnostic test runs and passes.

•	A scan tool can clear the MIL/DTC.

•	The PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without an emission-related diagnostic fault occurring.

•	The PCM cancels the DTC default actions when the ignition switch is OFF long enough in order to power down the PCM.

Test Description

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

This step tests the ability of the AT OSS to produce an AC voltage. This step also verifies the integrity of the wiring to the PCM.

This step tests the AT OSS circuit for correct resistance.

Step

Action

Value(s)

Yes

Did you perform the Diagnostic System Check - Engine Controls?

Go to Step 2

Go to Diagnostic System Check - Engine Controls in Engine Controls - 2.2L (L61)

Install a scan tool.
Turn ON the ignition, with the engine OFF.

Important: Before clearing the DTC, use the scan tool to record the Freeze Frame and Failure Records. Using the Clear Info function erases the Freeze Frame and Failure Records from the PCM.

Record the DTC Freeze Frame and Failure Records.
Clear the DTC.

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.

Raise and support the drive wheels.
Start and idle the engine.
Place the transmission in DRIVE.
Select Transmission OSS on the scan tool.

With the drive wheels rotating, does Transmission OSS increase when the wheel speed increases?

Go to Intermittent Conditions in Engine Controls - 2.2L (L61)

Go to Step 3

Turn OFF the ignition.
Disconnect the PCM connectors C1 and C2.
Using the J-35616 connector test adapter kit, connect the DMM between PCM terminal C2-64 and C2-42.
Select AC volts.
Turn ON the ignition, with the engine OFF.
Rotate the right front drive wheel by hand.
Observe the DMM display.

Can a voltage greater than the specified value be obtained?

0.5 V AC

Go to Step 14

Go to Step 4

Leave the DMM test leads connected.
Measure circuit resistance.

Is the circuit resistance within the specified range?

1,530-1,870 ohms

Go to Step 8

Go to Step 5

Is the circuit resistance greater than the specified value?

1,870 ohms

Go to Step 11

Go to Step 6

Leave the DMM test leads connected.
Disconnect the AT OSS connector at the transmission.

Is the circuit resistance less than the specified value?

1,530 ohms

Go to Step 7

Go to Step 13

Test the high signal circuit (CKT 400) and the low signal circuit (CKT 401) of the AT OSS for being shorted together.

Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 15

Test the high signal circuit (CKT 400) of the AT OSS for a short to ground.

Refer to Testing for Short to Ground and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 15

Go to Step 9

Connect PCM connectors C1 and C2 .
Select DC volts.
Using the J-35616 connector test adapter kit, connect the DMM test leads to terminal A and B of the AT OSS connector end.
Turn ON the ignition, with the engine OFF.

Does the DMM display system voltage?

Go to Step 10

Go to Step 12

Test the high signal circuit (CKT 400) of the AT OSS for a short to voltage.

Refer to Testing for a Short to Voltage and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 15

Test the high signal circuit (CKT 400) of the AT OSS for an open.
Test the low signal circuit (CKT 401) of the AT OSS for an open.

Refer to Testing for Continuity and Wiring Repairs in Wiring Systems.

Did you find and correct a condition?

Go to Step 15

Go to Step 13

Remove the AT OSS.

Refer to Vehicle Speed Sensor Replacement

Inspect the AT OSS and the transmission for the following conditions:

•	Incorrect AT OSS

•	AT OSS damage

•	Excessive AT OSS to speed sensor rotor gap

•	Incorrect speed sensor rotor alignment

•	Speed sensor rotor damage

Repair any of the above conditions as necessary.

Refer to Final Drive Assembly Disassemble or Output Speed Sensor Installation

Did you complete the repair?

Go to Step 15

Replace the AT OSS.

Refer to Vehicle Speed Sensor Replacement .

Did you complete the replacement?

Go to Step 15

Replace the PCM.

Refer to Powertrain Control Module Replacement in Engine Controls - 2.2L (L61).

Did you complete the replacement?

Go to Step 15

Perform the following procedure in order to verify the repair:

Select DTC.
Select Clear Info.
Operate the vehicle and ensure that the transmission OSS is greater than 300 RPM for 2 seconds.
Select Specific DTC.
Enter DTC P0503.

Has the test run and passed?

Go to Step 16

Go to Step 2

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?

Go to Diagnostic Trouble Code (DTC) List in Engine Controls - 2.2L (L61)

System OK

DTC P0503 3.0L (L81)

Master Electrical Component List
Automatic Transmission Controls Schematics 3.0L
OBD II Symbol Description Notice

Circuit Description

The automatic transmission output shaft speed sensor (AT OSS) provides vehicle speed information to the TCM. The AT OSS is a permanent magnet generator mounted to the transmission case. The AT OSS produces an AC voltage as the transmission speed sensor rotor teeth pass through the magnetic field of the sensor. The AC voltage level increases as the speed of the vehicle increases. The TCM converts the AC voltage into a digital signal. The TCM uses the vehicle speed signal to determine shift timing, torque converter clutch (TCC) apply, TCC release, and gear ratio calculations.

When the TCM detects a loss of vehicle speed while the vehicle is in motion, then DTC P0503 sets. DTC P0503 is a type B DTC.

Conditions for Running the DTC

•	No MAP DTCs P0107 or P0108.

•	No MAF DTCs P0101, P0102, or P0103.

•	No Shift Solenoid Electrical DTC P1843.

•	No AT ISS DTCs P0716 or P0717.

•	The engine is running for 5 seconds.

•	An increase in output speed of 250 RPM or greater has not occurred for greater than 2 seconds.

•	An increase in input speed of 500 RPM or greater has not occurred for greater than 2 seconds.

•	The engine torque is between 100-150 N·m (74-110 lb ft).

Conditions for Setting the DTC

Output speed drops greater than 1,200 RPM for 3 seconds.

Action Taken When the DTC Sets

•	The TCM requests the ECM to illuminate the malfunction indicator lamp (MIL) during the second consecutive trip in which the Conditions for Setting the DTC are met.

•	The TCM commands maximum line pressure.

•	The TCM freezes transmission adaptive functions.

•	The TCM calculates output speed from input speed, engine speed, and commanded gear.

•	The ECM records the operating conditions when the Conditions for Setting the DTC are met. The ECM stores this information as Freeze Frame and Failure Records.

•	The TCM records the operating conditions when the Conditions for Setting the DTC are met. The TCM stores this information as Failure Records.

•	The TCM stores DTC P0503 in TCM history during the second consecutive trip in which the Conditions for Setting the DTC are met.

Conditions for Clearing the MIL/DTC

•	The ECM turns OFF the MIL after the third consecutive drive trip in which the TCM does not send a MIL illumination request.

•	A scan tool can clear the MIL/DTC.

•	The TCM clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without an emission-related diagnostic fault occurring.

•	The TCM cancels the DTC default actions when the ignition switch is OFF long enough in order to power down the TCM.

Test Description

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

This step tests the ability of the AT OSS to produce an AC voltage. This step also verifies the integrity of the wiring to the PCM.

This step tests the AT OSS circuit for correct resistance.

Step

Action

Value(s)

Yes

Did you perform the Diagnostic System Check - Engine Controls?

Go to Step 2

Go to Diagnostic System Check - Engine Controls in Engine Controls - 3.0L (L81)

Install a scan tool.
Turn ON the ignition, with the engine OFF.

Important: : Before clearing the DTC, use the scan tool in order to record the Freeze Frame and Failure Records. Using the Clear Info function erases the Freeze Frame and Failure Records from both the ECM and the TCM.

Record the DTC Freeze Frame and Failure Records.
Clear the DTC.

Raise and support the drive wheels.
Start and idle the engine.
Place the transmission in DRIVE.
Select Transmission OSS on the scan tool.

With the drive wheels rotating, does Transmission OSS increase when the wheel speed increases?

Go to Intermittent Conditions in Engine Controls - 3.0L (L81)

Go to Step 3

Turn OFF the ignition.
Disconnect the TCM connectors C1 and C2.
Using the J-35616 connector test adapter kit, connect the DMM between TCM terminal C2-44 and C2-23.
Select AC volts.
Turn ON the ignition, with the engine OFF.
Rotate the right front drive wheel by hand.
Observe the DMM display.

Can a voltage greater than the specified value be obtained?

0.5 V AC

Go to Step 14

Go to Step 4

Leave the DMM test leads connected.
Measure circuit resistance.

Is the circuit resistance within the specified range?

1,530-1,870 ohms

Go to Step 8

Go to Step 5

Is the circuit resistance greater than the specified value?

1,870 ohms

Go to Step 11

Go to Step 6

Leave the DMM test leads connected.
Disconnect the AT OSS connector at the transmission.

Is the circuit resistance less than the specified value?

1,530 ohms

Go to Step 7

Go to Step 13

Test the high signal circuit (CKT 400) and the low signal circuit (CKT 401) of the AT OSS for being shorted together.

Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 15

Test the high signal circuit (CKT 400) of the AT OSS for a short to ground.

Refer to Testing for Short to Ground and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 15

Go to Step 9

Connect TCM connectors C1 and C2.
Select DC volts.
Using the J-35616 connector test adapter kit, connect the DMM test leads to terminal A and B of the AT OSS connector end.
Turn ON the ignition, with the engine OFF.

Does the DMM display system voltage?

Go to Step 10

Go to Step 12

Test the high signal circuit (CKT 400) of the AT OSS for a short to voltage.

Refer to Testing for a Short to Voltage and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 15

Test the high signal circuit (CKT 400) of the AT OSS for an open.
Test the low signal circuit (CKT 401) of the AT OSS for an open.

Refer to Testing for Continuity and Wiring Repairs in Wiring Systems.

Did you find and correct a condition?

Go to Step 15

Go to Step 13

Remove the AT OSS.

Refer to Vehicle Speed Sensor Replacement

Inspect the AT OSS and the transmission for the following conditions:

•	Incorrect AT OSS

•	AT OSS damage

•	Excessive AT OSS to speed sensor rotor gap

•	Incorrect speed sensor rotor alignment

•	Speed sensor rotor damage

Repair any of the above conditions as necessary.

Refer to Final Drive Assembly Disassemble or Output Speed Sensor Installation

Did you complete the repair?

Go to Step 15

Replace the AT OSS.

Refer to Vehicle Speed Sensor Replacement .

Did you complete the replacement?

Go to Step 15

Replace the TCM.

Refer to Transmission Control Module Replacement

Did you complete the replacement?

Go to Step 15

Perform the following procedure in order to verify the repair:

Select DTC.
Select Clear Info.
Operate the vehicle and ensure that the transmission OSS is greater than 300 RPM for 2 seconds.
Select Specific DTC.
Enter DTC P0503.

Has the test run and passed?

Go to Step 16

Go to Step 2

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?

Go to Diagnostic Trouble Code (DTC) List in Engine Controls - 3.0L (L81)

System OK