GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

1

  1. Disconnect the scan tool from the data link connector (DLC).
  2. Turn the ignition switch to the RUN position.
  3. Connect a DMM between terminal 2 and 4 of the DLC.

Is the voltage reading greater than the specified value?

7 volts

Go to Step 2

Go to Step 9

2

  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 1.

Is the voltage reading greater than the specified value?

7 volts

Go to Step 5

Go to Step 3

3

  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 1.

Is the voltage reading greater than the specified value?

7 volts

Go to Step 4

Go to Step 17

4

  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 1.

Is the voltage reading greater than the specified value?

7 volts

Go to Step 7

Go to Step 17

5

  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 1.

Is the voltage reading greater than the specified value?

7 volts

Go to Step 6

Go to Step 17

6

  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 1.

Is the voltage reading greater than the specified value?

7 volts

Go to Step 8

Go to Step 17

7

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

Is the repair complete?

--

Go to Control Module References

--

8

  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 in Wiring Systems.
  2. Reconnect C100.

Is the repair complete?

--

Go to Control Module References

--

9

  1. Turn the ignition switch to the OFF position.
  2. Connect a DMM (continuity) between cavity 2 of the DLC and ground.

Is continuity present?

--

Go to Step 10

Go to Control Module References

10

  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 13

Go to Step 11

11

  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 12

Go to Step 17

12

  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 15

Go to Step 17

13

  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 14

Go to Step 17

14

  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 16

Go to Step 17

15

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

Is the repair complete?

--

Go to Control Module References

--

16

  1. Locate and repair the short to ground in CKT 1807 (PPL) between the DLC and the VTD, C100 and the transfer case shift control module. Refer to Wiring Repairs in Wiring Systems.
  2. Reconnect C100.

Is the repair complete?

--

Go to Control Module References

--

17

Replace the control module that you disconnected last.

Is the repair complete?

--

Go to Control Module References

--