2001 Chevrolet/Geo Camaro  

DTC P0503 5.7 L


Object Number: 644773 Size: SF
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Master Electrical Component ListAutomatic Transmission Controls SchematicsOBD II Symbol Description Notice
Circuit Description

The vehicle speed sensor (VSS) assembly provides vehicle speed information to the powertrain control module (PCM). The VSS assembly is a permanent magnet generator. The VSS produces an 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 PCM converts the 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 Running the DTC
Conditions for Setting the DTC

The transmission output speed drop is greater than 1300 RPM for 3 seconds when the transmission is not in PARK or NEUTRAL.

Action Taken When the DTC Sets
Conditions for Clearing the MIL/DTC
Diagnostic Aids
Test Description

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

  1. Disable the traction control system when performing this step. When the ignition switch is cycled OFF and then back ON, the traction control system defaults to ON.

  2. This step tests the VSS assembly circuit.

  3. This step tests the integrity of the VSS assembly.

DTC P0503 (5.7 L)

Step

Action

Value(s)

Yes

No

1

Did you perform the Powertrain Diagnostic System Check?

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Go to Step 2

Go to Diagnostic System Check - Engine Controls in Engine Controls - 5.7 L

2
  1. Install a Scan Tool .
  2. 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 the PCM.

  3. Record the DTC Freeze Frame and Failure Records.
  4. Clear the DTC.
  5. Raise and support the rear axle assembly.
  6. Start the engine.
  7. Disable the traction control system.
  8. Place the transmission in D3 range.
  9. With the drive wheels rotating, slowly accelerate to 2000 engine RPM and hold. (Road test the vehicle if necessary).

Does the Scan Tool Transmission OSS drop or fluctuate more than the specified value?

1300 RPM

Go to Step 3

Go to Intermittent Conditions in Engine Controls - 5.7 L

3
  1. Turn OFF the ignition.
  2. Disconnect the PCM connector C2.
  3. Using the J 39200 digital multimeter (DMM) and the J 35616-A connector test adapter kit, measure the resistance between harness connector terminals C2-20 and C2-21.

Does the resistance measure within the specified range?

1377-3355 ohms

Go to Step 4

Go to Step 7

4
  1. Place the transmission in NEUTRAL.
  2. Select AC volts.
  3. Prevent one rear wheel from turning.
  4. Rotate the other rear wheel by hand, ensuring that the driveshaft is turning.

Does the voltage measure greater than the specified value?

0.5 volts

Go to Step 5

Go to Step 12

5

Measure the resistance from terminal C2-21 to ground.

Does the resistance measure greater than the specified value?

50 K ohms

Go to Step 6

Go to Step 9

6
  1. Reconnect the PCM connector C2.
  2. Disconnect the engine wiring harness from the VSS assembly.
  3. Turn ON the ignition, with the engine OFF.
  4. Test the high signal circuit (CKT 821) of the VSS assembly for a short to power. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 15

Go to Step 14

7
  1. Disconnect the engine wiring harness from the VSS assembly.
  2. Measure the resistance of the VSS assembly.

Does the resistance measure within the specified range?

1377-3355 ohms

Go to Step 8

Go to Step 13

8

Was the resistance measured in Step 3 greater than the specified value?

3355 ohms

Go to Step 10

Go to Step 11

9

Test the high signal circuit (CKT 821) of the VSS assembly for a short to ground.

Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 15

--

10
  1. Test the high signal circuit (CKT 821) of the VSS assembly for an open.
  2. Test the low signal circuit (CKT 822) of the VSS assembly for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 15

--

11

Test the high signal circuit (CKT 821) and the low signal circuit (CKT 822) of the VSS assembly for a short together.

Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 15

--

12
  1. Remove the VSS assembly.
  2. Inspect the output shaft speed sensor rotor for damage or misalignment.
  3. Inspect the case extension bushing for wear.

Did you find and correct the condition?

--

Go to Step 15

Go to Step 13

13

Replace the VSS assembly.

Refer to Vehicle Speed Sensor (VSS) Replacement .

Did you complete the replacement?

--

Go to Step 15

--

14

Replace the PCM.

Refer to Powertrain Control Module (PCM) Replacement in Engine Controls - 5.7 L.

Did you complete the replacement?

--

Go to Step 15

--

15

Perform the following procedure in order to verify the repair:

  1. Select DTC.
  2. Select Clear Info.
  3. Operate the vehicle, ensuring that the transmission output speed drop is less than 500 RPM for 2 seconds and output speed is greater than 500 RPM for 2 seconds.
  4. Select Specific DTC.
  5. Enter DTC P0503.

Has the test run and passed?

--

System OK

Go to Step 1