For 1990-2009 cars

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Did you perform the Lighting System Diagnostic System Check? | -- | Go to Step 2 | Go to Diagnostic System Check - Lighting Systems
2 |

1. Turn the headlamp and I/P lamp dimmer switch to the HEAD position.
2. Press and release the rear fog lamp switch

Are both rear fog lamps operating properly?

--

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

Go to Step 3

3 | Did only one rear fog lamp illuminate? | -- | Go to Step 10 | Go to Step 4
4 | Does the rear fog lamp indicator illuminate inside the rear window wiper/washer and multifunction switch? | -- | Go to Step 5 | Go to Step 12
5 | Use a test lamp in order to backprobe between the RH rear fog lamp connector, terminal C and ground. Does the test lamp light? | -- | Go to Step 6 | Go to Step 9
6 | Use a test lamp in order to backprobe between the RH rear fog lamp connector, terminal C and terminal E. Does the test lamp light? | -- | Go to Step 7 | Go to Step 8
7 | Replace the rear fog lamps. Refer to Tail Lamp Replacement Has the repair been made and the system rechecked? | -- | Go to Step 27 | --
8 | Repair the following conditions in CKT 350.

• | A poor connection

• | An open

Has the repair been made and the system rechecked?

--

Go to Step 27

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9 | Repair the following conditions in CKT 122 between S243 and S419:.

• | A poor connection

• | An open

Has the repair been made and the system rechecked?

--

Go to Step 27

--

10 | Test for an open or high resistance in the operative rear fog lamp power supply or ground circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 27 | Go to Step 11
11 | Replace the inoperative rear fog lamp. Refer to Tail Lamp Replacement Has the repair been made and the system rechecked? | -- | Go to Step 27 | --
12 |

1. Remove the fog lamp relay.
2. Use a test lamp in order to backprobe the rear fog lamp relay terminal B3 and ground.
3. Use a test lamp in order to backprobe the rear fog lamp relay terminal B1 and ground.

Does the test lamp light for both tests?

--

Go to Step 13

Go to Step 14

13 | Install a fused jumper across terminal B3 and terminal C3 of the rear fog lamp relay connector. Do the fog lamps illuminate? | -- | Go to Step 16 | Go to Step 15
14 | Repair the following conditions in CKT 1640 between the rear fog lamp relay and the S270:

• | A poor connection

• | An open

Has the repair been made and the system rechecked?

--

Go to Step 27

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15 | Repair the following conditions in CKT 122 between the rear fog lamp relay and the S243:

• | A poor connection

• | An open

Has the repair been made and the system rechecked?

--

Go to Step 27

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16 | Use a test lamp in order to backprobe the rear fog lamp relay terminal B1 and terminal C1. Does the test lamp light? | -- | Go to Step 17 | Go to Step 18
17 | Replace the rear fog lamp relay. Has the repair been made and the system rechecked? | -- | Go to Step 27 | --
18 |

1. Disconnect the rear fog lamp module.
2. Use a DMM in order to measure the voltage between the rear fog lamp module terminal L and ground.

Is the voltage within the specified range?

B+

Go to Step 20

Go to Step 19

19 | Repair the following conditions in CKT 10 between the rear fog lamp module terminal L and the headlamp and I/P dimmer switch terminal L:

• | A poor connection

• | An open

Has the repair been made and the system rechecked?

--

Go to Step 27

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20 | Use a DMM in order to measure the voltage between the rear fog lamp module terminal L and terminal B. Is the voltage within the specified range? | B+ | Go to Step 22 | Go to Step 21
21 | Repair the following conditions in CKT 1450 between the rear fog lamp module terminal B and ground G200:

• | A poor connection

• | An open

Has the repair been made and the system rechecked?

--

Go to Step 27

--

22 |

1. Use a DMM in order to measure voltage between the rear fog lamp module terminal E and B+.
2. Observe the meter while pressing the rear fog lamp switch.

Is the voltage within the specified range?

B+

Go to Step 25

Go to Step 23

23 |

1. Disconnect the window wiper/washer and multifunction switch connector.
2. Use a DMM in order to backprobe the rear window wiper/washer and multifunction switch connector C3 terminal B and B+.

Is the voltage within the specified range?

B+

Go to Step 24

Go to Step 26

24 | Inspect for a poor connection or an open circuit in CKT 1977. If the circuit is good, replace the rear window wiper/washer and multifunction switch. Refer to Multifunction Switch Assembly Replacement - Instrument Panel . Has the repair been made and the system rechecked? | -- | Go to Step 27 | --
25 | Inspect for a poor connection or an open circuit in CKT 1870. If the circuit is good, replace the rear fog lamp module. Has the repair been made and the system rechecked? | -- | Go to Step 27 | --
26 | Repair the following conditions in CKT 1450 between the rear window wiper/washer and multifunction switch terminal B and ground G200:

• | A poor connection

• | An open

Has the repair been made and the system rechecked?

--

Go to Step 27

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27 | Operate the system in order to verify the repair. Did you correct the condition? | -- | System OK | Go to Step 2