GM Service Manual Online
For 1990-2009 cars only

Object Number: 626145  Size: SF
Engine Controls Components
Tach, Clutch Switch, VSS Output and VSS Signal
OBD II Symbol Description Notice
Powertrain Control Module Connector End Views
Handling ESD Sensitive Parts Notice

Circuit Description

The clutch pedal position switch is a normally closed switch. The powertrain control module (PCM) applies a voltage (B+) to the clutch pedal position switch circuit. When the clutch pedal position switch is depressed or the clutch pedal is released, the circuit is open and the PCM senses a high voltage. When the clutch pedal position switch is released or the clutch pedal is depressed, the clutch pedal position switch contacts close, causing the applied voltage to go low.

The PCM determines if the clutch pedal position switch has failed by not sensing a clutch switch transition. The PCM monitors vehicle speed from 0 to a predetermined speed.

Conditions for Running the DTC

No vehicle speed sensor (VSS) diagnostic trouble codes (DTCs)

Conditions for Setting the DTC

    • Vehicle speed goes from 0 km/h (0 mph) to more than 39 km/h (24 mph) and back to 0 km/h (0 mph) for 2 seconds without the PCM detecting a clutch transition.
    • This occurs 7 times before the diagnostic reports a fault.

Action Taken When the DTC Sets

    • The powertrain control module (PCM) stores the DTC information into memory when the diagnostic runs and fails.
    • The malfunction indicator lamp (MIL) will not illuminate.
    • The PCM records the operating conditions at the time the diagnostic fails. The PCM stores this information in the Failure Records.

Conditions for Clearing the DTC

    • A History DTC will clear after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.
    • A last test failed, or current DTC, will clear when the diagnostic runs and does not fail.
    • Use a scan tool in order to clear the DTC.

Diagnostic Aids

Important: 

   • Remove any debris from the PCM connector surfaces before servicing the PCM. Inspect the PCM connector gaskets when diagnosing or replacing the PCM. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion into the PCM.
   • For any test that requires probing the PCM or a component harness connector, use the J 35616 connector test adapter kit. Using this kit prevents damage to the harness and component terminals. Refer to Using Connector Test Adapters in Wiring Systems.

    • The following may cause an intermittent:
       - Poor connections -- Refer to Intermittents and Poor Connections Diagnosis in Wiring Systems.
       - Corrosion
       - Mis-routed harness
       - Rubbed through wire insulation
       - Broken wire inside the insulation
    •  For an intermittent condition, refer to Symptoms .

Test Description

The number below refers to the step number on the diagnostic table.

  1. This step determines if the fault is present.

Step

Action

Values

Yes

No

1

Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?

--

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

2

  1. Install a scan tool.
  2. Turn ON the ignition leaving the engine OFF.
  3. Monitor the clutch pedal position switch parameter using the scan tool.
  4. Depress and release the clutch pedal several times.

Does the scan tool display change states when the clutch pedal is depressed and released?

--

Go to Diagnostic Aids

Go to Step 3

3

Inspect the adjustment of the clutch pedal position switch.

Was an adjustment necessary?

--

Go to Step 14

Go to Step 4

4

  1. Turn OFF the ignition.
  2. Disconnect the clutch pedal position switch connector.
  3. Turn ON the ignition leaving the engine OFF.
  4. Measure the voltage from the clutch pedal position signal circuit using the DMM. Refer to Measuring Voltage in Wiring Systems.

Does the DMM display the specified voltage?

B+

Go to Step 5

Go to Step 6

5

  1. Jumper the clutch pedal position switch terminals together using a fused jumper wire. Refer to Using Fused Jumper Wires in Wiring Systems.
  2. Monitor the clutch pedal position switch parameter using a scan tool.

Does the scan tool display the Clutch Switch Released?

--

Go to Step 9

Go to Step 8

6

Test the continuity of the clutch pedal signal circuit using the DMM connected to ground. Refer to Testing for Continuity in Wiring Systems.

Does the DMM display continuity?

--

Go to Step 11

Go to Step 7

7

  1. Turn OFF the ignition.
  2. Disconnect the PCM connector C1 located on the same side as the manufacturer logo. Refer to Powertrain Control Module Replacement/Programming .
  3. Test the continuity of the clutch pedal signal circuit using the DMM. Refer to Testing for Continuity in Wiring Systems.

Does the DMM display continuity?

B+

Go to Step 10

Go to Step 11

8

Test the continuity of the clutch pedal ground circuit using the DMM. Refer to Testing for Continuity in Wiring Systems.

Does the DMM display continuity?

--

Go to Step 9

Go to Step 12

9

  1. Inspect for poor connections at the clutch pedal position switch connector. Refer to Intermittents and Poor Connections Diagnosis in Wiring Systems.
  2. If you find a poor connection, repair the condition as necessary. Refer to Connector Repairs in Wiring Systems.

Did you correct the condition?

--

Go to Step 15

Go to Step 13

10

  1. Inspect for poor connections at the PCM. Refer to Intermittents and Poor Connections Diagnosis in Wiring Systems.
  2. If you find a poor connection, repair the condition as necessary. Refer to Connector Repairs in Wiring Systems.

Did you correct the condition?

--

Go to Step 15

Go to Step 14

11

Repair the clutch pedal position switch signal circuit. Refer to Wiring Repairs in Wiring Systems.

Is the action complete?

--

Go to Step 15

--

12

Repair the clutch pedal position switch ground circuit. Refer to Wiring Repairs in Wiring Systems.

Is the action complete?

--

Go to Step 15

--

13

Replace the clutch pedal position switch.

Is the action complete?

--

Go to Step 15

--

14

Important: The replacement PCM must be programmed.

Replace the PCM. Refer to Powertrain Control Module Replacement/Programming .

Is the action complete?

--

Go to Step 15

--

15

  1. Select the Diagnostic Trouble Codes (DTC) option and the Clear DTC Information option using the scan tool.
  2. Idle the engine at the normal operating temperature.
  3. Select the Specific DTC option under the Diagnostic Trouble Code (DTC) option using a scan tool.
  4. Operate vehicle within the Conditions for Running this DTC as specified in the supporting text, if applicable.

Does the scan tool indicate that this test ran and passed?

--

Go to Step 16

Go to Step 2

16

Select the Capture Info option and the Review Info option using the scan tool.

Are any DTCs displayed that you have not diagnosed?

--

Go to the applicable DTC table

System OK