GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

DEFINITION: This table diagnoses the shift lever never being unlocked.

1

Were you sent here from the Brake Transmission Shift Interlock System Check?

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Go to Step 2

Go to Automatic Transmission Shift Lock Control System Check

2

  1. Disconnect the shift lock control module connector.
  2. Turn the ignition switch to ON.
  3. Test for B+ in cavity 5 of the shift lock control module connector using a J 39200 .

Was B+ measured?

--

Go to Step 4

Go to Step 3

3

Repair the open in the BLK/YEL wire between cavity 5 of the shift lock control module connector and cavity 9 of connector C7 of junction block 2. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Automatic Transmission Shift Lock Control System Check

--

4

With the ignition switch still in the ON position and the shift lock control module connector still disconnected:

Test for B+ in cavity 1 of the shift lock control module connector using a J 39200 .

Was B+ measured?

--

Go to Step 6

Go to Step 5

5

Repair the open in the GRY wire between cavity 1 of the shift lock control module connector and cavity 1 of connector C2 of the multifunction alarm module. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Automatic Transmission Shift Lock Control System Check

--

6

With the shift lock control module connector still disconnected:

Test for continuity between cavity 3 of the shift lock control module connector and ground using a J 39200 .

Is there continuity in the WHT/BLK wire?

--

Go to Step 8

Go to Step 7

7

Repair the open in the WHT/BLK wire between cavity 3 of the shift lock control module connector and ground. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Automatic Transmission Shift Lock Control System Check

--

8

With the shift lock control module connector still disconnected:

  1. Disconnect connector C3 of junction block 2.
  2. Press the brake pedal.
  3. Test for continuity between cavity 2 of the shift lock control module connector and cavity 7 of connector C3 of junction block 2 using a J 39200 .

Is there continuity?

--

Go to Step 14

Go to Step 9

9

Test for continuity between cavity 2 of the shift lock control module connector and cavity 1 of the stoplamp switch using a J 39200 .

Is there continuity in the GRN/WHT wire?

--

Go to Step 11

Go to Step 10

10

Repair the open in the GRN/WHT wire between cavity 2 of the shift lock control module and cavity 1 of the stoplamp switch. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Automatic Transmission Shift Lock Control System Check

--

11

Press the brake pedal and test for continuity between cavities 1 and 2 of the stoplamp switch using a J 39200 .

Is there continuity?

--

Go to Step 13

Go to Step 12

12

Replace/adjust the stoplamp switch. Refer to Stop Lamp Switch Replacement or Stop Lamp Switch Adjustment in Hydraulic Brakes.

Is the adjustment or replacement complete?

--

Go to Automatic Transmission Shift Lock Control System Check

--

13

Repair the open in the RED/WHT wire between cavity 2 of the stoplamp switch and cavity 7 of connector C3 of junction block 2. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Automatic Transmission Shift Lock Control System Check

--

14

Replace the shift lock control module. Refer to Shift Lock Control Module Replacement in Automatic Transmissions 3 Speed - MB3 or Shift Lock Control Module Replacement in Automatic Transmissions 4 Speed - MS7.

Is the repair complete?

--

Go to Automatic Transmission Shift Lock Control System Check

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