Chevrolet 1999 Silverado 1500 Pickup Owner's Manual page 340

4. If a CHMSL bulb is replaced, put the bulb into the
socket and press it in until it is tight.
5. If a cargo lamp is replaced, put a new cargo lamp
bulb into the socket and press it in until it is tight.
before turning the socket counterclockwise.
6. Put the holder back plate into the lamp housing
7. Replace the lamp assembly and tighten the screws.
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Taillamps (Pickup Models)
1. Open the tailgate.
2. Remove the two rear lamp assembly screws near the
tailgate latch and pull out the lamp assembly.
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