GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 1998 🢒 GMC Suburban - 2WD 🢒 Driveline/Axle 🢒 Transfer Case - NVG 246-NP8 (Two Speed Automatic) 🢒 Service Indicator Inoperative

Object Number: 450722 Size: MF
Transfer Case Control Components
Transfer Case Control Schematics Automatic 4WD

Test Description

The number(s) below refer to the step number(s) on the diagnostic table.

  1. This step determines if the transfer case shift control module has electronic control of the Service Indicator.

    2.

  2. This step determines if there is an internal fault with the transfer case shift control module.

    3.

  3. This step check CKT 1567 for open.

    4.

  4. This step check CKT 39 for open.

Service Indicator Does Not Light

Step

Action

Value(s)

Yes

No

1

Was the Transfer Case Diagnostic System Check performed?

--

Go to Step 2

Go to Transfer Case Diagnostic System Check

2
  1. Connect a Scan Tool .
  2. Turn the ignition to RUN, engine OFF.
  3. Use the Scan Tool in order to command the Service Indicator On.

Does the Service Indicator turn On?

--

Go to Step 11

Go to Step 3

3
  1. Turn the ignition to RUN, engine OFF.
  2. Disconnect both connectors at the transfer case shift control module.
  3. Connect a fused jumper wire from the at the transfer case shift control module harness connector C1 terminal E2 to ground.

Does the Service Indicator turn On?

--

Go to Step 11

Go to Step 4

4
  1. Disconnect the connector at the Instrument cluster.
  2. Connect a Scan Tool Digital Multimeter DMM between the instrument cluster harness connector terminal 24 and transfer case shift control module harness connector C1 terminal E2 and measure the resistance.

Is the resistance within the specified values?

0-5ohms

Go to Step 5

Go to Step 8

5

Connect a Scan Tool DMM between the instrument cluster harness connector terminal 22 and ground.

Is the voltage reading within the specified values?

9-14 V

Go to Step 6

Go to Step 9

6

Inspect the Service Indicator lamp bulb for open.

Is the Service Indicator lamp bulb for open?

--

Go to Step 10

Go to Step 7

7

Service Instrument Cluster for an open condition.

Is the action complete?

--

Go to Step 12

--

8

Repair open in CKT 1567. Refer to Wiring Repairs in Electrical Diagnostics.

Is the repair complete?

--

Go to Step 12

--

9

Repair open in CKT 39. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Step 12

--

10

Replace the Service Indicator lamp bulb. Refer to Instrument Cluster Bulb Replacement in the instrument cluster.

Is the repair complete?

--

Go to Step 12

--

11

Replace the transfer case shift control module. Refer to Transfer Case Shift Control Module Replacement .

Is the action complete?

--

Go to Step 12

--

12
  1. Ensure the ignition is OFF.
  2. Properly mount and reconnect all previously disconnected ATC components.

Have all the ATC components been reconnected and properly mounted?

--

Go to Step 13

--

13

Clear all ATC DTCs.

Have all the ATC DTCs been cleared?

--

Go to Transfer Case Diagnostic System Check

--