GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 1998 🢒 GMC Suburban - 4WD 🢒 Body and Accessories 🢒 Wiring Systems 🢒 Scan Tool Does Not Communicate with Class 2 Data Line

Step

Action

Value(s)

Yes

No

1

Did you perform the Data Link Communications System Check?

--

Go to Step 2

Go to Diagnostic System Check - Data Link Communications

2
  1. Disconnect the scan tool from the Data Link Connector (DLC).
  2. Turn the ignition switch to the RUN position.
  3. Connect a J 39200 between terminals 2 and 4 of the DLC.

Is the voltage reading greater than the specified value?

7 volts

Go to Step 3

Go to Step 10

3
  1. Turn the ignition to the OFF position.
  2. Disconnect connector C100.
  3. Take the same reading between terminals 2 and 4 of the DLC as in step 2.

Is the voltage reading greater than the specified value?

7 volts

Go to Step 6

Go to Step 4

4
  1. Turn the ignition to the OFF position.
  2. Reconnect connector C100.
  3. Disconnect connector C1 of the electronic brake control module (EBCM).
  4. Take the same reading between terminals 2 and 4 of the DLC as in step 2.

Is the voltage reading greater than the specified value?

7 volts

Go to Step 5

Go to Step 18

5
  1. Turn the ignition to the OFF position.
  2. Disconnect the vehicle control module (VCM) or powertrain control module (PCM).
  3. Take the same reading between terminals 2 and 4 of the DLC as in step 2.

Is the voltage reading greater than the specified value?

7 volts

Go to Step 8

Go to Step 18

6
  1. Turn the ignition to the OFF position.
  2. Disconnect the EVO/Passlock Module (VTD).
  3. Take the same reading between terminals 2 and 4 of the DLC as in step 2.

Is the voltage reading greater than the specified value?

7 volts

Go to Step 7

Go to Step 18

7
  1. Turn the ignition to the OFF position.
  2. Disconnect the Transfer Case Shift Control Module connector C1.
  3. Take the same reading between terminals 2 and 4 of the DLC as in step 2.

Is the voltage reading greater than the specified value?

7 volts

Go to Step 9

Go to Step 18

8

Locate and repair the short to voltage in CKT 1807 (PPL) between C100 and the EBCM, VCM/PCM. Refer to Wiring Repairs

Is the repair complete?

--

Go to Diagnostic System Check - Data Link Communications

--

9
  1. Locate and repair the short to voltage in CKT 1807 (PPL) between the DLC and the VTD, C100 and the Transfer Case Shift Control Module. Refer to Wiring Repairs
  2. Reconnect C100.

Is the repair complete?

--

Go to Diagnostic System Check - Data Link Communications

--

10
  1. Turn the ignition switch to the OFF position.
  2. Connect a J 39200 between terminals 2 and 4 of the DLC.

Is continuity present?

--

Go to Step 11

Go to Diagnostic System Check - Data Link Communications

11
  1. Disconnect connector C100.
  2. Take the same reading between terminals 2 of the DLC and ground as in step 10.

Is continuity present?

--

Go to Step 14

Go to Step 12

12
  1. Reconnect connector C100.
  2. Disconnect connector C1 of the Electronic Brake Control Module (EBCM).
  3. Take the same reading between terminals 2 of the DLC and ground as in step 10.

Is continuity present?

--

Go to Step 13

Go to Step 18

13
  1. Disconnect the Vehicle Control Module (VCM) or Powertrain Control Module (PCM).
  2. Take the same reading between terminals 2 of the DLC and ground as in step 10.

Is continuity present?

--

Go to Step 16

Go to Step 18

14
  1. Disconnect the EVO/Passlock Module (VTD).
  2. Take the same reading between terminals 2 of the DLC and ground as in step 10.

Is continuity present?

--

Go to Step 15

Go to Step 18

15
  1. Disconnect the Transfer Case Shift Control Module connector C1.
  2. Take the same reading between terminals 2 of the DLC and ground as in step 10.

Is continuity present?

--

Go to Step 17

Go to Step 18

16

Locate and repair the short to voltage in CKT 1807 (PPL) between C100 and the EBCM, VCM/PCM. Refer to Wiring Repairs

Is the repair complete?

--

Go to Diagnostic System Check - Data Link Communications

--

17
  1. Locate and repair the short to voltage in CKT 1807 (PPL) between the DLC and the VTD, C100 and the Transfer Case Shift Control Module. Refer to Wiring Repairs
  2. Reconnect C100.

Is the repair complete?

--

Go to Diagnostic System Check - Data Link Communications

--

18

Replace the control module that you disconnected last.

Is the repair complete?

--

Go to Diagnostic System Check - Data Link Communications

--