This is a pretty stupid question since I have been driving my '03 MC for 7 years, but where exactly are the rear parking lights? the dealer told me all 4 parking bulbs were out so I figured I would save some money and replace them myself.
The owner's manual doesn't show where any of the lights are on the exterior so I did some web searching and figured out how to replace the front ones, thank you @how. But the rear panel has 3 bulbs and is going to be painful to extract so I want to know exactly which bulb needs done before I try it.
Why are there no diagrams of this?

 

In an '03, the rear parking light is the bottom bulb in the taillight. Actually it is a dual filament (1157) bulb for both brake and parking. You can reach in through the luggage compartment and release the bulbholder panel that holds all 3 bulbs. Unclip a horizontal tab underneath the wiring harness connector. It might help to disconnect the connector first (probably have to press on a tab to pull it off).

 

Thanks for the info. I just looked at the assessment from the dealer and it says that the 4 Front parking lights are out. I replaced the bulbs in the small round units in the bumper, but where would the other 2 be?

 

Are they possibly referring to the front wheel arch lights too?

 

No idea, what are arch lights? I know about headlights and high beams. there is now mention of arch lights in the manual. Is there a annotated diagram of the lights on this car? The only info in the owner's manual shows where the controls inside are, but not where the various lights are on the exterior.

 

The arch lights are in the black trim around the wheels. They look like reflectors (orange at front wheels, red at rear wheels), and they light up when parking lights are turned on.

 

OK, got that figured out, now is there a way I can replace the bulbs in the front sides of the bumper?

 

Well I finally worked it out.
1. Open the bonnet, remove a small screw at the outer edge of the bumper, right above the arch light, it is parallel to the ground.
2. Carefully pull out the bumper edge to make room, remove the two clips holding the plastic light cover prongs in place.
3. Use a screwdriver to pry out the light cover.
4. Twist and pull out the light bulb holder at the top.
5. Replace the bulb and put everything back together!