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Home >> Chevrolet >> 2006 >> Cobalt LTZ >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 8 (Manual Transaxle - Mu3 - Service & Diagnosis) >> Diagnostic Information and Procedures >> DTC P0502 >> Test Description

Test Description

WARNING: This page is about a different variant/trim than selected.

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

  1. 3:  This step tests the ability of the VSS to produce an AC voltage. This step also verifies the integrity of the wiring to the PCM.
  2. 4:  This step tests the VSS circuit for correct resistance.
DTC P0502

Step Action Value(s) Yes No
1 Did you perform the Diagnostic System Check - Vehicle? - Go to Step 2  Go to Diagnostic System Check - Vehicle
2
  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
    3. 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. NOTE: 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. Raise and support the drive wheels.
  6. Start and idle the engine.
  7. Place the transmission in 1st gear.
  8. Select Vehicle Speed Sensor on the scan tool.
With the drive wheels rotating, does the Vehicle Speed Sensor parameter increase when the wheel speed increases?		 - Go to Testing for Intermittent Conditions and Poor Connections Go to Step 3 
3 
  1. Turn OFF the ignition.
  2. Disconnect the PCM connector C3.
  3. Using the J 35616  GM-approved terminal test kit, connect the DMM between the VSS high signal circuit and the VSS low signal circuit at the PCM C3 connector.
  4. Select AC volts.
  5. Turn ON the ignition, with the engine OFF.
  6. Rotate the right front drive wheel by hand.
  7. 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 
4 
  1. Leave the DMM test leads connected.
  2. Measure circuit resistance.
Is the circuit resistance within the specified range?		 1,300-3,160 Ω Go to Step 8  Go to Step 5 
5 Is the circuit resistance greater than the specified value? 3,160 Ω Go to Step 11  Go to Step 6 
6
  1. Leave the DMM test leads connected.
  2. Disconnect the VSS connector at the transmission.
Is the circuit resistance less than the specified value?		 1,300 Ω Go to Step 7  Go to Step 13 
7 Test the high signal circuit and the low signal circuit of the VSS for being shorted together. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?		 - Go to Step 15  -
8 Test the high signal circuit of the VSS for a short to ground. Refer to Testing for Short to Ground and Wiring Repairs .
Did you find and correct the condition?		 - Go to Step 15  Go to Step 9 
9
  1. Connect PCM C3.
  2. Select DC volts on the DMM.
  3. Using the J 35616  , connect the DMM test leads to the VSS high signal and the VSS low signal circuit of the VSS connector.
  4. Turn ON the ignition, with the engine OFF.
Does the DMM display system voltage?		 - Go to Step 10  Go to Step 12 
10 Test the high signal circuit of the VSS for a short to voltage. Refer to Testing for a Short to Voltage and Wiring Repairs .
Did you find and correct the condition?		 - Go to Step 15  -
11
  1. Test the high signal circuit of the VSS for an open.
  2. Test the low signal circuit of the VSS for an open.
Refer to Testing for Continuity and Wiring Repairs .Did you find and correct a condition?		 - Go to Step 15  Go to Step 13 
12
  1. Remove the VSS. Refer to Vehicle Speed Sensor (VSS) Replacement .
  2. Inspect the VSS and the VSS rotor for the following conditions:
    • VSS damage
    • VSS rotor damage
    • Excessive air gap between the VSS rotor and the VSS
    • Incorrect alignment between the VSS and the VSS rotor
  3. Repair any of the above conditions as necessary.
Did you find and correct a condition?		 - Go to Step 15  -
13 Replace the VSS. Refer to Vehicle Speed Sensor (VSS) Replacement .
Did you complete the replacement?		 - Go to Step 15  -
14 Replace the PCM. Refer to Control Module References for replacement, setup, and programming.
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 and ensure that the VSS is greater than 250 RPM for 2 seconds.
  4. Select Specific DTC.
  5. Enter DTC P0502.

Has the test run and passed?		 - Go to Step 16  Go to Step 2 
16 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 - Vehicle System OK
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