GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

1

Is the turn signal lamp that is inoperative a front turn signal lamp?

--

Go to Step 5

Go to Step 2

2

  1. Turn the ignition switch to the RUN.
  2. Place the turn signal switch to the inoperative side.
  3. Using a test light, backprobe between the inoperative turn lamp harness connector terminal A and ground.

Is the test light flashing?

--

Go to Step 13

Go to Step 3

3

    • If the left side is inoperative: repair a poor connection or an open in circuit 18.
    • If the right side is inoperative: repair a poor connection or an open in circuit 19.

Has the repair been made?

--

Go to Exterior Lights System Check

--

4

Replace the rear turn lamp. Refer to Rear Turn Signal Lamp Bulb Replacement .

Has the repair been made?

--

Go to Exterior Lights System Check

--

5

Inspect the turn telltale light flash.

Does the turn telltale light flash for the inoperative side when the turn signal is ON?

--

Go to Step 7

Go to Step 6

6

    • If the left side is inoperative: repair a poor connection or an open in circuit 14 between C201 terminal A13 and the underhood accessory wiring junction block harness connector C2 terminal C12.
    • If the right side is inoperative: repair a poor connection in circuit 15 between C201 terminal A12 and he underhood accessory wiring junction block harness connector C2 terminal C10.

Has the repair been made?

--

Go to Exterior Lights System Check

--

7

Place the turn signal switch to the inoperative side.

Does the side repeater lamp flash?

--

Go to Step 8

Go to Step 10

8

  1. Turn the ignition to the RUN.
  2. Place the turn signal to the inoperative side.
  3. • If the left side is inoperative: using a test light, backprobe between the underhood accessory wiring junction block harness connector C2 terminal B7 to ground.
    • If the right side is inoperative: using a test light, backprobe between the underhood accessory wiring junction block harness connector C2 terminal D11 to ground.

Does the test light flash?

--

Go to Step 11

Go to Step 10

9

    • If the left side is inoperative: repair a poor connection or an open in circuit 14 between the underhood accessory wiring junction block connector C3 terminal B7 and the LH headlamp connector C141 terminal D.
    • If the right side is inoperative: repair a poor connection or an open in circuit 15 between the underhood accessory wiring junction block connector C2 terminal D11 and the RH headlamp connector C142 terminal D.

Has the repair been made?

--

Go to Exterior Lights System Check

--

10

Replace the underhood accessory wiring junction block. Refer to Accessory Wiring Junction Block Replacement in Body Front End.

Has the repair been made?

--

Go to Exterior Lights System Check

--

11

  1. Turn the ignition switch to the RUN.
  2. Place the turn signal to the inoperative side.
  3. Using a test light, backprobe between the inoperative side headlamp harness connector terminal D and ground.

Does the test light flash?

--

Go to Step 12

Go to Step 9

12

Replace the headlamp. Refer to Headlamp Replacement .

Has the repair been made?

--

Go to Exterior Lights System Check

--

13

Using a test light, backprobe the inoperable turn lamp harness connector terminal A to terminal B.

Does the test light flash?

--

Go to Step 4

Go to Step 14

14

    • If the left side is inoperative: repair a poor connection or an open in circuit 250 between the LR turn lamp harness connector terminal B and G401.
    • If the right side is inoperative: repair a poor connection or an open in circuit 350 between the RR turn lamp harness connector terminal B and G402.

Has the repair been made?

--

Go to Exterior Lights System Check

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