GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 1999 🢒 GMC K Pickup - 4WD 🢒 Engine 🢒 Engine Controls - 5.0L and 5.7L 🢒 Manual Transmission Shift Light

Object Number: 32861 Size: MF
Handling ESD Sensitive Parts Notice
Handling ESD Sensitive Parts Notice
OBD II Symbol Description Notice
4WD, IAC, and Upshift Controls
Engine Controls Components

Circuit Description

The control module controls the shift lamp using the following inputs:

    • The Engine Coolant Temperature (ECT) sensor
    • The Throttle Position (TP) sensor
    • The Vehicle Speed sensor (VSS)
    • The Engine RPM

The control module uses the measured RPM and the vehicle speed in order to calculate what gear the vehicle is in. This calculation determines when the shift lamp should be turned ON.

Test Description

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

  1. This step checks the control module's ability to control the shift lamp.

Step

Action

Value(s)

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. Turn OFF the ignition.
  2. Install a scan tool.
  3. Turn ON the ignition leaving the engine OFF.
  4. Using the scan tool, command the shift lamp ON.

Is the shift lamp ON?

--

Go to Step 4

Go to Step 3

3
  1. Disconnect the VCM connector that contains the shift lamp control circuit.
  2. Turn ON the ignition leaving the engine OFF.
  3. Connect a fused jumper between the shift lamp control circuit and ground.

Is the shift lamp ON?

--

Go to Step 5

Go to Step 6

4

Using the scan tool, command the shift lamp OFF and ON.

Does the shift lamp respond to the scan tool command?

--

System OK

Go to Step 8

5

Check the shift lamp control circuit for a poor terminal connection at the VCM connector.

Did you find a problem?

--

Go to Step 7

Go to Step 10

6

Repair the open in the shift lamp circuit.

Is the action complete?

--

Go to Step 11

--

7

Repair the circuit as necessary. Refer to Connector Repairs in Wiring Systems.

Is the action complete?

--

Go to Step 11

--

8
  1. Turn OFF the ignition.
  2. Disconnect the VCM connector that contains the shift lamp control circuit.
  3. Turn ON the ignition leaving the engine OFF.

Is the shift lamp ON?

--

Go to Step 9

Go to Step 10

9

Repair the short to ground in the shift lamp control circuit. Refer to Wiring Repairs in Wiring Systems.

Is the action complete?

--

Go to Step 11

--

10
  1. Replace the VCM.
  2. Program the new VCM. Refer to VCM Replacement/Programming .
  3. Perform the Passlock Reprogramming Procedure. Refer to PASSLOCK Reprogramming Seed and Key in Theft Deterrent.
  4. Perform the CKP System Variation Learn Procedure. Refer to Crankshaft Position System Variation Learn .

Is the action complete?

--

Go to Step 11

--

11
  1. Using the scan tool, clear the DTCs.
  2. Start the engine.
  3. Allow the engine to idle until the engine reaches normal operating temperature.
  4. Select DTC and the Specific DTC function.
  5. Enter the DTC number which was set.
  6. Operate the vehicle, with the Conditions for Setting this DTC, until the scan tool indicates the diagnostic Ran.

Does the scan tool indicate the diagnostic Passed?

--

Go to Step 12

Go to Step 2

12

Does the scan tool display any additional undiagnosed DTCs?

--

Go to the applicable DTC table

System OK