When the C4 Corvette came on the scene in the early ’80s, it was viewed as a technological advancement much like the mid-engine Corvette is today. It took the world by storm, and the ability to near 1g lateral acceleration by mere mortals put smiles on faces for just over a decade.
Owners of 1984-1989 models were instantly met with a (for the time) Corvette dash with an amazing light show of LCD gauges that thrust you forward into the 21st century, even before the car started to move. While the light show through the steering wheel was an amazing feat for the era, after many years, it has typically shown the need for touch-ups.
Thankfully, companies such as Batee Electronic Parts and Repair are making it easier for enthusiasts to keep the dash lights on in their C4 Corvettes. Bryan Thompson, owner of Batee.com offers many of the parts necessary and numerous videos to address any concerns one might have with their C4 dash. Batee also offers restoration services for those who would rather trust the work to someone with more experience. We prefer to do our own stunts. and we contacted the folks at Batee.com to bring the factory functionality back to our ’85 Corvette’s dash.
Corvette Dash Trouble Areas
Even though electrical components don’t move like many mechanical things, they can still wear out or be affected by age and weathering. One of the most often issues with the C4 Corvette dash is when the dash is obviously lit up. After time, the numbers are no longer readable. After running out of fuel (twice) because we could not read the “Reserve” warning, we knew we had a problem.
The C4 dash has a special polarizing film on the face of the gauge which allows the digits to become legible. Over time, sunlight and heat diminish the film’s ability to properly polarize the light. Living in Florida makes this an all-to-real possibility. Like our C4, you may notice small segments of your Corvette dash going blank as the damage creeps over the entire gauge face.
If you feel the polarizing film is to blame, you can put on a pair of polarizing glasses and see if the gauge comes back to life. Batee offers replacement film for the gauge glass and sent us a small sample so we could test the gauge cluster to see if that was the issue with our gauges. It was.
Other areas that can be problematic are when the backlighting flickers or doesn’t respond to changes of outside lighting situations. There are several reasons why this may be occurring and Batee again, helps explain the issue, and how to fix it. They also offer the necessary photocell, specific connections, and also the proper bulbs to rebuild your dash to be better than new.
Even electronic wonders are still prone to mechanical issues. The instrument power supply board can fail, rendering your Corvette dash a useless black void. Batee has created an updated power supply to address a failed power source and even improve its performance over the factory version thanks to advancements in electronics technology.
The way the boards within the dash join together allows for arcing over time which can create bad connections. The small motor which controls the odometer can fail, bulbs can burn out, and even the glass plates which comprise the gauge face can become damaged and break.
Breaking Down The Corvette Dash
Once you remove the gauge cluster and take the back cover off, you’ll notice the cluster is built in layers. Before disassembly, it’s best to remove the odometer assembly and set it aside. There are two control boards stacked on top of each other with a 12-pin connector routing electricity between them. The first board also contains the power supply board and is held in place by small screws. By removing the screws and gently working the 12-pins out of the board, you can then remove the upper board.
The lower board is static sensitive but needs to be removed to fix our faded gauges. Carefully remove the screws holding the second board in position and place it aside where it will not be damaged. Handle the board by the edges just enough to remove it and place it aside.
There are several components held in place by the inner board which can now be removed. Your Corvette dash has plastic housings that hold the gauge faces into position and contain the elastomeric connectors (pink rubber blocks) which you may find stuck to the glass of the gauge. Once you remove the plastic housings, you can remove the light diffusers for each gauge face, as well as the color filter sheet which gives each gauge its color.
At this point, you can carefully remove the glass panes (gauge faces). The pink elastomeric connectors can be peeled off of the glass carefully. Be careful with these, as you’ll need them for reassembly. You don’t want to tear them.
Polarizing Film Replacement
Looking at the glass plates, you’ll notice one side is painted and the other side is the polarizing film. Do not peel the painted side. Batee offers black paint with its kit to touch up any paint that may have peeled or been damaged over the years. Light will show through where there is no paint, and likewise, you don’t want to get any paint on areas where it shouldn’t be.
On the other side of the glass, you’ll likely see the faded, polarizing film, which is easily removed with a small razor blade. Place the glass sheet on a solid, but safe surface, not a towel. You want something that won’t damage the painted surface, but also keeps even pressure on the backside so the glass doesn’t break.
You can then clean the glass with a glass cleaner to remove any residue. Polarizing film is directional, so it matters which way is up when installing it. Batee has marked the film to make installation easier. If it is installed incorrectly, it will need to be removed and replaced. Double-check the orientation before applying!
As mentioned, some issues are caused by connectors that have oxidized or cold-solder joints which have lost their continuity. One of the main culprits is the 12-pin connector. Joints, where each connector meets their respective boards, can become cold-solder joints and where the pins slide into the female side of the connector can become oxidized or carboned.
Check each of the pins thoroughly as well as each of the solder joints on both of the boards. If you need to swap out the connector, or if you need to re-solder one or two joints, you can use a solder wick to remove the old solder. Then just resolder the joint to good as new. Check each joint thoroughly, as you don’t want to have to go back in to do it again.
Identifying the issues with your particular Corvette dash will let you know what components need replacing. Batee has a great series of videos to help you. Other components like the photocell may need replacing. In each situation, simply wick out the old solder and replace the component.
Installing The C4 Dash
Reinstalling the components back into the gauge housing is the reverse of disassembly, but extreme care must be given to make sure the glass panes are seated properly in the housing before you tighten the screws which hold the inner board in place. They could easily be broken or cracked if the board presses down on them unevenly due to not being properly seated.
When installing the elastomeric connectors, you will note they are different sizes. Batee recommends marking the position of each pink connector so they go back into the same slots and orientation they came out. You can re-install the connectors once the glass panes, color filter, light diffusers, and plastic retainer housings are installed.
You also want to make sure the 12-pin connector is cleaned and seated properly before installing the upper board. It should slide over and make contact with each of the pins. If not, the gauge cluster will not work properly.
After everything is reinstalled and the backplate is secure, we went ahead and installed the gauges to try them out before re-assembling our Corvette dash. This way, if there is a problem, we can easily remove the gauge cluster and find out why.
We were happy to see all of our gauges come to life and now we’re able to see exactly what all those numbers and colored bars were trying to tell us! We no longer need to live in fear of running out of gas in our C4 Corvette. At least, not because our gauge wasn’t trying to warn us!