GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

1

Was the entire Exterior Lights System Check performed?

--

Go to Step 2

Go to Exterior Lights System Check

2

Backprobe the stoplamp/BTSI switch connector C1 with a DMM from cavity A (ORN) to ground.

Is the voltage within the specified range?

10-15 V

Go to Step 3

Go to Step 7

3

  1. Backprobe the stoplamp/BTSI switch connector C1 with a DMM from cavity B (WHT) to ground.
  2. Press the brake pedal.

Is the voltage within the specified range?

10-15 V

Go to Step 4

Go to Step 11

4

  1. Disconnect the stoplamp/BTSI switch connector C1.
  2. Connect a DMM from the stoplamp/BTSI switch connector C1 cavity B (WHT) to ground.

Is the resistance less than the specified value?

0.5 ohms

Go to Step 12

Go to Step 5

5

Connect a DMM from the stoplamp/BTSI switch connector C1 cavity B (WHT) to C400 or C403 cavity A (WHT).

Is the resistance less than the specified value?

0.5 ohms

Go to Step 6

Go to Step 13

6

Repair the open in CKT 17 (WHT) between the stoplamp/BTSI switch and the splice pack C302. Refer to Wiring Repairs in Wiring Systems.

Is the circuit repair complete?

--

Go to Exterior Lights System Check

--

7

Check the rear junction block STOP LP Fuse for an open.

Is the STOP LP Fuse OK?

--

Go to Step 10

Go to Step 8

8

Repair the short to ground in CKT 1640 (ORN). Refer to Wiring Repairs in Wiring Systems.

Is the circuit repair complete?

--

Go to Step 9

--

9

Replace the STOP LP Fuse in the rear junction block. Refer to Wiring Repairs in Wiring Systems.

Is the STOP LP Fuse replacement complete?

--

Go to Exterior Lights System Check

--

10

Repair the open in CKT 1640 (ORN) between the rear junction block and the stoplamp/BTSI switch. Refer to Wiring Repairs in Wiring Systems.

Is the circuit repair complete?

--

Go to Exterior Lights System Check

--

11

Replace the stoplamp/BTSI switch. Refer to Stop Lamp Switch Replacement in Brakes.

Is the stoplamp/BTSI switch replacement complete?

--

Go to Exterior Lights System Check

--

12

Repair the short to ground in CKT 17 (WHT). Refer to Wiring Repairs in Wiring Systems.

Is the circuit repair complete?

--

Go to Exterior Lights System Check

--

13

Repair the open in CKT 17 (WHT) between the stoplamp/BTSI switch and C302. Refer to Wiring Repairs in Wiring Systems.

Is the circuit repair complete?

--

Go to Exterior Lights System Check

--