For 1990-2009 cars

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
Important: A short to ground will cause an open fuse(s). Before performing this diagnostic procedure, inspect the fuse(s) for an open.
1 | Disconnect the brake switch connector C1. Do the lamps remain lit? | -- | Go to Step 2 | Go to Step 3
2 | Disconnect connector C3 of the left IP junction block. Do any of the stop lamps remain lit? | -- | Go to Step 4 | Go to Step 5
3 | Inspect the adjustment of the stoplamp switch. If the adjustment is OK, replace the stoplamp switch. Refer to Stop Lamp Switch Replacement in Hydraulic Brakes. Is the repair complete? | -- | Go to Exterior Lights System Check | --
4 | Repair the short to B+ in CKT 20 between the left IP junction block and the lit lamp. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Exterior Lights System Check | --
5 | Connect a test lamp between connector C3 terminal A12 of the left IP junction block and ground. Does the test lamp light? | -- | Go to Step 6 | Go to Step 7
6 | Repair the short to B+ in CKT 20 between the left IP junction block and the brake switch. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Exterior Lights System Check | --
7 |

1. Reconnect connector C3 of the left IP junction block.
2. Disconnect connector C2 of the left IP junction block.

Do the stop lamps remain lit?

--

Go to Step 8

Go to Step 9

8 | Replace the left IP junction block. Is the repair complete? | -- | Go to Exterior Lights System Check | --
9 |

1. Reconnect connector C2 of the left IP junction block.
2. Disconnect connector C3 of the underhood junction block.

Do the stop lamps remain lit?

--

Go to Step 10

Go to Step 11

10 | Repair the short to B+ in CKT 20 between the left IP junction block and the underhood junction block. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Exterior Lights System Check | --
11 |

1. Disconnect the underhood junction block connector C1.
2. Connect a test lamp between terminal A12 of the underhood junction block connector C1 and ground.

Does the test lamp light?

--

Go to Step 12

Go to Step 13

12 |

1. Disconnect the electronic brake control module (EBCM) connector.
2. Connect a test lamp between terminal 16 of the EBCM connector and ground.

Does the test lamp light?

--

Go to Step 14

Go to Step 15

13 |

1. Disconnect the underhood junction block connector C2.
2. Connect a test lamp between terminal B12 of the underhood junction block connector C2 and ground.

Does the test lamp light?

--

Go to Step 16

Go to Step 17

14 | Repair the short to B+ in CKT 20 between the underhood junction block and the EBCM. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Exterior Lights System Check | --
15 | Replace the EBCM. Refer to Electronic Brake Control Module Replacement in Antilock Brakes. Is the repair complete? | -- | Go to Exterior Lights System Check | --
16 |

1. Disconnect the cruise control module connector.
2. Connect a test lamp between terminal G of the cruise control module connector and ground.

Does the test lamp light?

--

Go to Step 18

Go to Step 19

17 | Replace the underhood junction block. Refer to Underhood Fuse Block Replacement in Engine Electrical. Is the repair complete? | -- | Go to Exterior Lights System Check | --
18 | Repair the short to B+ in CKT 20 between the underhood junction block and the cruise control module. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Exterior Lights System Check | --
19 | Replace the cruise control module. Refer to Cruise Control Module Replacement in Cruise Control. Is the repair complete? | -- | Go to Exterior Lights System Check | --