Lights
C4 Corvette Exterior Lights Guide
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Headlight Assemblies
C4 Corvettes used a motorized hideaway headlight design. The headlight assemblies had 4 variations over the C4 production run with the major difference being a motor change from the 1984-1987 design to the later 1988-1996 motors. There was a minor change to the light and motor wiring plug connections of the second motor design, where 1988-1990 used a two-plug connection (separate for the motor, and lighting wires) and 1991-1996 combined these wires into a single plug connection. The motors though remained the same from 1988-1996.
1984-1987 Headlight Motor Design
1988-1996 Headlight Motor Design
1988-1990 Two plug wiring connection.
1991-1996 Single plug wiring connection
1984 vs. 1985-1987 Headlight bracket difference.
The 1984 headlights are nearly identical to those from 1985-1987 but there is a minor difference. The top inside stud, that is fixed to the hood for mounting the headlight assemblies is slightly relocated in 1985-1987 hoods from where it is in 1984 hoods. The bracket on the headlight assemblies is therefore a different length between the years.
So… If you have an 85-87 car, and you are replacing an entire headlight assembly from a 1984, you will not be able to bolt down this top inside bracket as it will be too short. If you have a 1984, and are replacing with an 85-87 headlight assembly, you will need to drill an additional hole in the bracket to allow for the stud which is slightly more outward as compared to the 85-87 hoods.
1984 Headlight Bracket, Short upper inside bracket
Shown above on a 1985-1987 hood for displaying difference in stud locations.
1985-87 Headlight Bracket, Longer upper inside bracket
Headlight Bulbs
Headlight bulbs of C4 Corvette were a glass bulb design (Wagner H6054) that later changed to a plastic bulb design (Wagner HP6054). All headlight assemblies can use the glass or plastic bulb design. The plastic bulb was brought about in later years as a weight savings to the rotating mass of the headlight assemblies. As most owners know, the plastic headlight motor gears and bushings are a very common failure, and the reduced weight of the plastic bulbs in later years was in effort to reduce failures on the original plastic motor gears. The plastic Wagner bulbs are no longer in production and are becoming a more difficult part to find. Most of these bulb have poor light output as compared with modern headlights.
The year in which the changeover to the plastic headlight bulb varied between base model and ZR1 versions, base model corvettes used the glass bulb from 1984 up until mid way through 1992. While ZR1 models received the plastic bulbs earlier, mid way through 1990.
Wagner HP6054 Plastic Bulb
HP6054 Plastic case markings
Headlight Covers
The headlight covers, both the flat hood side and the bulb side cover, are the same from 1984-1996 and can be applied to all headlight assembly designs. However, as a note, the 1984-1985 headlight covers are made of a heavier and thicker material than later year C4’s. The weight difference is very noticeable when comparing the covers of these years with those from later C4’s.
Both covers are left and right side specific.
1984-1996 Headlight Bulb Cover
1984-1996 Headlight Lid, Flat Cover
Fog Light / Parking Light Assemblies
The fog light and parking light assemblies changed with the major body changes of the 1991 models. The earlier 1984-1990 design used a unique connection plug for the fog light bulb and is one of the points that need modified in a headlight wiring harness if converting an 84-90 front end to a 1991 or later. The later style fog light assembly will also not sit correctly in the 84-90 front bumper support and requires the support to be changed for correct converting of front end styles.
One of the major drawbacks to the fog light assemblies of both designs is that it requires removal of the front bumper cover to change a damaged housing.
1984-1990 Fog Light / Parking Light, RH side shown
1984-1990 Fog Light / Parking Light Housing, RH side rear view
1991-1996 Fog Light / Parking Light, RH side shown
1991-1996 Fog Light / Parking Light, RH side, underside view
Side Marker Lights
Front: C4 Corvettes used 3 designs for the front bumper side marker lights. These were 1984-1987, 1988-1990 and 1991-1996. It is important to note that the 84-90 side marker lights appear identical on the outside surface. However, the plug connection style for the small amber bulb was one of the changes in 1988 when many “beneath the surface” changes occurred to C4’s.
1984-1990 Front side marker light, LH side, 84-87 shown
1984-1987 Front side marker light, housing view
1988-1990 Front side marker light housing view
Note the change in connection style to the housing for the small bulb socket.
1991-1996 Front side marker light, LH side
Rear: The rear bumper side marker lights had 3 designs as well but all look nearly identical. Those year ranges are 1984-1987, 1988-1990, and 1991-1996. Like the front side marker lights, the difference between the 1987 and 1988 lights is the connection type used on the smaller bulb. For 1984-1987 and 1988-1990 an easy way to spot the difference from a distance is that the earlier housings will be gray in color where as the later ones are black. This is true for both the front and rear side marker lights.
The outside surface of these lights appear physically the same for all years. However, the 1991-1996 rear side marker lights have a darkened tint to the clear portion of the lens. See below photo which shows the difference in outside apperance between 1984-1990 and 1991-1996. Also note that the 1990 ZR1 used the untinted side marker light same as base model 1990’s even though the rear bumper was of the later style. Even with the change in tint, the same GM part number is present on these housings.
1984-1990 vs 1991-1996 Rear side marker lights
1984-1987 Rear side marker light, housing view
1988-1996 Rear side marker light ,housing view
Note the change in connection style to the housing for the small bulb socket.
Tail lights
C4 Corvettes used two designs of tail lights. Round lights for 1984-1990 and a more squared off or oval type design for 1991-1996. (1990 in ZR-1’s)
A very common issue with even low mileage C4’s is cracking of the tail light housing at the point where the mounting bolts secure it to the rear bumper cover. This issue is seen more often on the later 91-96 style lights but is also present on earlier round lights as well.
The 1984-1990 round lights do not have a removable lens surface whereas the 1991-1996 lights do have a removable lens that can be easily changed out. Unlike some other years of corvettes, all tail lights are able to be applied to left or right sides for C4’s.
Note* The guide markings on all tail lights indicate the year in which the taillight design was first made. 84-90 tail lights are marked with “83 guide”. The 91-96 lights are marked “88 guide” as they were designed earlier on for ZR-1 prototype work.
1984-1990 Tail lights
1991-1996 (90-95 ZR-1) Tail Lights
Third Brake Lights
There were 4 designs of third brake lights for C4 corvettes. 1986-1990 Coupes had theirs mounted on top of the rear glass hinge plate. 1990-1995 ZR-1 also used this same style third brake light as the 86-90 coupes. 1986-1990 Convertibles used two designs, 86-88 and 89-90. Then in 1991-1996 coupes and convertibles used a common design.
1986-1990 (90-95 ZR-1) Third brake light location
1986-1990 Convertible Third brake light location
1986-1988 Convertible third brake light
1986-1988 Convertible third brake light, Rear housing
1989-1990 Convertible third brake light
1991-1996 Coupe / Convertible Third brake light
Reverse Lights
Two styles of reverse lights were used for C4 Corvettes. A 1984-1990 design and a 1991-1996 (1990-1995 ZR1) design. The two designs are similar with the 1991 and up design being a little wider than the earlier style. The two designs can not be interchanged in early and late bumper covers.
1984-1990 Reverse light
1991-1996 (90-95 ZR-1) Reverse light
Rear License Plate / Ground Illumination Light
The rear license plate light and rear ground illumination light used the same style light housings. However, the rear ground illumination light that is mounted underneath the rear bumper was not applied in 1994 -1996 models as the rear bumper impact support structure was modified from a rubber honeycomb to a foam design for 1994 and up. There were also two different housing designs due to a bulb plug connection change similar to the side marker lights. This change also occured in 1988.
1984-1996 Rear license plate / ground illumination light
1984-1987 Bulb socket connection style
1988-1996 Bulb socket connection style
For further information on replacement items for your C4 corvette please feel free to give us a call or contact us with any questions.