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Home >> Chevrolet >> 2006 >> Cobalt LTZ >> Repair and Diagnosis >> External Pages >> Different car >> Section 698 (Manual Transmission - GETRAG (M86)) >> Diagnostic Information and Procedures >> DTC P0502 >> Test Description

Test Description

WARNING: This page is about a different car, the 2007 Pontiac G5 Pursuit, 2007 Pontiac G5, and 2007 Chevrolet Cobalt. However, it is still accessible from the selected car via links, so may be relevant.

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 ECM.
  2. 4:  This step tests the VSS circuit for correct resistance.
DTC P0502

Step Action Value(s) Yes No
Schematic Reference: Manual Transmission Schematics 
Connector End View Reference: Manual Transmission Connector End Views 
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 ECM.
  3. Record the DTC Freeze Frame and Failure Records.
  4. Clear the DTC.
  5. Raise and support the drive wheels.
  6. Start and idle the engine.
  7. Engage the transmission in 2nd gear.
  8. Select Vehicle Speed Sensor on the scan tool.
With the drive wheels rotating, does Vehicle Speed Sensor 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 ECM connector C2.
  3. Using the J 35616  GM terminal test kit, connect the DMM between the vehicle speed sensor (VSS) high signal circuit and the VSS low signal circuit at the ECM connector.
  4. Select AC volts on the DMM.
  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?		 977-2,354 Ω Go to Step 8  Go to Step 5 
5 Is the circuit resistance greater than the specified value? 2,354 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?		 977 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 ECM connector C2.
  2. Select DC volts on the DMM.
  3. Using the J 35616  , connect the DMM test leads to the VSS high signal circuit and the VSS low signal circuit of the VSS wiring harness 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 Test the high signal circuit and 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 Front Wheel Speed Sensor Replacement .
  2. Inspect the VSS and the transmission for the following conditions:
    • Incorrect VSS
    • VSS damage
    • Excessive VSS to speed sensor rotor gap
    • Incorrect speed sensor rotor alignment
    • Speed sensor rotor damage
  3. Repair any of the above conditions as necessary.
Did you complete the repair?		 - Go to Step 15  -
13 Replace the VSS. Refer to Front Wheel Speed Sensor Replacement .
Did you complete the repairs?		 - Go to Step 15  -
14 Replace the ECM. Refer to Control Module References for replacement, setup, and programming.
Did you complete the repairs?		 - Go to Step 15  -
15 Perform the following procedure in order to verify the repair:
  1. Select DTC.
  2. Select Clear Info.
  3. Test drive the vehicle.
  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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