Buy Chevrolet (Chevy) G20 Tail Light Assembly

Quick Summary

The Chevrolet G20 van's tail light-also called the rear lamp, brake light, or rear combination lamp-keeps traffic behind you aware when you slow down, stop, or turn. It must fit model-year ranges (1971-1995), meet federal lighting rules, and use durable lenses, tight wiring, and the correct dual-filament 1157 bulb or an LED equivalent.

Van Background

The third-generation Chevrolet G-series vans, which include the ¾-ton G20, were built from 1971 to 1996 and share many body and lighting parts across the run (Wikipedia).
The G20's heavy-duty suspension and six-lug wheels demanded a slightly larger rear lamp opening than lighter G10 models (Top Gear Wiki).

Tail Light Basics

A tail light assembly houses three main functions: running lamp (low-intensity red when the headlights are on), stop lamp (high-intensity red during braking), and turn signal/hazard functions (NHTSA).
Federal Motor Vehicle Safety Standard (FMVSS) 108 says these lamps must burn steadily-no flashy pulsing is allowed for stop lamps on U.S. roads (NHTSA).
Since September 1, 1985, vans also require a separate center high-mounted stop lamp (CHMSL) for extra warning (NHTSA).
FMVSS 108 also fixes tail-lamp color at red and bans other hues for those functions (NHTSA).

Years & Fit

• 1971-1977 - round tail-lamp pockets; converting to later rectangular lamps needs sheet-metal trimming.
• 1978-1995 - rectangular lamp pocket; direct swap across these years.
• 1996 final-year vans kept the same lamp shell but added a molded alignment tab to speed assembly.
  A popular do-it-yourself video shows how builders swap early and late lamps between G10, G20, and G30 bodies (YouTube).

Design & Materials

Most lenses are molded from PMMA (acrylic) because it lets 90-92 % of light through and resists UV-yellowing (PMMA).
Industry engineers confirm PMMA is the standard tail-lamp lens resin; it injects cleanly and stays clear for years (Eng-Tips).
Housings are typically ABS or polypropylene to handle vibration.

Bulb & Light Source

All 1978-1995 G20 tail lights use a dual-filament 1157 (S8) bulb: one filament for running, one for stop/turn (JustAnswer).
LED retrofit lamps light 0.2-0.3 s faster than incandescent, giving drivers behind roughly 16 ft more stopping distance at 55 mph (Peterson Manufacturing).
When upgrading, be sure the LED is CAN-bus safe or add a load-equalizer to avoid hyper-flash.

Wiring & Installation

Typical wire colors on G-series vans:

• Brown - tail/parking lamp
• Yellow - left stop/turn
• Dark-green - right stop/turn
• Light-blue - stop feed (some years)
• Black - ground
  Field technicians on ChevyTalk share full rear-lamp diagrams for 1989 models, which largely match other years (ChevyTalk).
  Always disconnect the negative battery terminal and test each circuit with a multimeter before splicing.

Troubleshooting & Symptoms

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Maintenance & Care

Keep lens faces clean; dirt can cut light output by 40 % and hide cracks (NHTSA).
Apply dielectric grease to bulb bases to block moisture.
Check harness grounds yearly; surface rust under the rear bumper is a common cause of dim or flickering lights on older G20s.

Legal & Safety

Running with a failed stop lamp raises rear-end-collision risk; NHTSA shows rear impacts make up about 29 % of crashes .
LED conversions are legal if the assembly meets FMVSS 108 photometry and color rules; never tint the lens so dark that red output falls below spec (NHTSA).

Upgrade Options

• LED assemblies - brighter, quicker response, lower current draw.
• Smoked but DOT-approved lenses - style without illegal dark-out.
• Sequential turn modules - eye-catching but must still meet steady-burn brake rule (NHTSA).
• Polycarbonate guards - for off-road builds needing impact protection.

Vehicle Specs Snapshot

A mid-1990s G20 weighs about 4,568 lb curb and rides on a 125-in wheelbase (Edmunds).
Early-1990s base vans list similar wheelbase and dimensions on other spec sheets (Kbb.com).
Knowing weight helps choose a compatible LED load resistor (match to the van's 12-V, 14-A stop-lamp circuit).

Frequently Asked Questions

Q: What bulb number does a 1985-1995 G20 tail light use?
A: A dual-filament 1157 bulb, which handles both running-light and stop/turn functions (JustAnswer).

Q: Can I swap a 1975 round lamp to the later rectangular style?
A: Yes, but you must enlarge the sheet-metal opening and drill new mounting holes. Some builders weld in a patch plate for strength (YouTube).

Q: Are LED tail lights plug-and-play on a G20?
A: Physical fit is easy, but you may need resistors or an electronic flasher to keep the turn-signal speed normal (Peterson Manufacturing).

Q: Why does my right rear lamp stay dim even with a new bulb?
A: Check the black ground wire-loose or rusty grounds are the top cause of dim lights on older vans (ChevyTalk).

Q: What lens material lasts longest?
A: PMMA acrylic is standard for clarity and UV resistance, but high-end replacements may add polycarbonate guards for impact strength (PMMA).

Q: Is it legal to make my tail lights flash while braking?
A: No. FMVSS 108 requires stop lamps to be steady burning on passenger vehicles (NHTSA).

Q: Do all model years need the third brake light?
A: Only vans built on or after September 1, 1985 require the CHMSL under federal law (NHTSA).

Q: How fast do LEDs light compared to stock bulbs?
A: Roughly a quarter-second sooner, which can give the driver behind you an extra car length of reaction space at highway speeds (Peterson Manufacturing).

Q: My lens is cracked-can I repair it with clear tape?
A: Tape is a temporary fix. Moisture will still enter and corrode the socket; replace the entire rear light assembly as soon as possible (NHTSA).

Q: What torque should I use on the lamp mounting screws?
A: Hand-tight with a nut-driver (about 15 in-lb). Over-tightening can crack the acrylic lens (Eng-Tips).