Good all Forum Members who have always been there for me and my 78SA...

It appears that all of my exterior and under the hood work is done for this season..

My to the point ? is...What is involved in replacing all of the bulbs in the speed/tach and main cluster...I mean just level with me....I am an average DIY'er so please let me have some idea of what's REALLY involved...

As usual..thanks upfront for all inputs/comments tips etc!!!

mk's

Mike

 

A CAMERA! It may not seem important but each step needs pics.......ductwork sections before they are removed......and especially the routing of wiring bundles in case you have to pull them out of their locations to make it easier to change out bulbs---it can be very hard to put the gauges back into place if the bundles are not tucked in completely.

Also take pics of the wiring/bulb locations on the back of the gauges...sometimes the stamped markings are not easy to read.

Hopefully you can complete the project in a short time....if delays happen and it takes days to get back to the project you may not remember exactly where things belong.

 

Access. With the dash and center cluster installed, it's next to impossible to get to the lamps.

 

It's not difficult and requires only the most basic tools like a socket set and #2 Phillips both regular length and stubby. Actually a #2 POZI driver (they look almost identical to a Phillips) is a good idea as nearly all of the interior screws are POZI. Phillips bits work but the heads wear much more quickly.

Before I give some instructions here is some general advice:

A complete interior screw set is about $30 from most vendors and I would not at all be surprised if you wind up needing enough of them throughout the entire care to justify the expense. At the age of our cars it's not only common to find them missing but also quite work.

Be certain to get the proper bulbs. All of the vendors sell them but you can sincerely get them less expensively from a seller that specializes in light bulbs like Bulbtown. As with the interior screws it is not a bad idea to buy replacements for all of the bulbs in the car. While some bulbs look identical they can be electrically different. This is particularly true in the dash. The most expensive way to buy the bulbs is at a local store which may well not carry all of the proper ones anyhow. Vendors sell complete bulb kits if you don't want to bother with correctly identifying them before buying from a bulb specialty seller.

For the dash and gauge pack you need three distinct types of bulbs that from the outside look identical.

I'm not certain of the number but buy a box of 192s. These are used for the general illumination in both the cluster and gauge pack. If the bulb doesn't light a specific warning/indicator light (like turn signal, BRAKE, LOW FUEL, etc.) use a 192. These are rated at 3 lumens (candlepower).

You need eight 194s. These are used for the warning/indicator lights and the washer/wiper switch. They are rated at 2 lumens. A full box of 12 may be cheaper than 8.

You need one 158. This is for the "lantern" installed at the top center of the gauge pack that shines down to the climate control panel. It is rated at 3 lumens and while it may look to a 192 the very front of it is actually a lens. Use the wrong bulb and the lighting for the climate control is nearly useless!

You need one 161 for the transmission selector indicator. It is 1 lumen.

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Disassembly instructions. If you haven't bought a replacement screw set it's a good idea to "bag and tag" screws from each area/component.

Instrument panel cluster:

1) Disconnect negative battery cable!

2) Remove the driver side foot well courtesy lamp from its slot in the dash directly below the steering wheel--if it's actually installed there that is as it is very easy to break the piece that retains it.

3) Remove the two screws holding the headlamp door override switch panel directly below the steering wheel.

4) Remove the duct running to the left side dash register.

5) Fully loosen the two bolts you see holding the steering wheel in position (they go straight up). The steering wheel will not come loose, it will just drop a little bit.

6) Put the steering wheel all the way down and out (this presumes you have a T/T--tilt & telescope--wheel.

7) Remove 8 screws from the instrument cluster. One at each side and six above. There are two different sized screws at the top; one very short and one longer arranged in three "pairs" of one of each size.

8) Remove the cluster lens.

9) Reach behind the cluster directly behind the speedomenter. In the center of the speedo you will feel a large cable--this is the speedometer cable. At the six-o'clock position of the connection to the speedometer you will feel a little tab. Press it in (rearward) and this will release the cable.

10) Slide the cluster out slightly and reach behind to roughly the center. You'll feel good-sized electrical cable leading to a rectangular, vertically installed connector. Press the release tabs at both the top and bottom of the connector and pull directly out (towards the front of the car).

11) You can now worm out the entire cluster assembly. You generally have to push down on the steering column.

12) While the cluster is out, do not forget to replace the bulb in the washer/wiper switch! It's nearly (or perhaps completely) impossible to replace with the cluster installed. Like the rest of the bulbs it is in a base that you remove by twisting slightly counter-clockwise and pulling out.

13) Replace all of the bulbs using the proper bulbs in the proper places.

14) Before reassembly carefully examine the printed circuit behind the cluster. Look for signs of delamination of the layers which eventually leads to traces touching one another and shorting out. Also check the area of the space where the connector enters looking for broken/loose connection ends. You can cement a delaminated printed circuit back together with a decent cement (like Duco) and some appropriate clamps (often clothes pins). Loose ends at the connection point can be very carefully attached with thick type super glue being extremely careful not to get any glue on the upper mating surfaces of each end. Replacement printed circuits are readily available and while not terribly expensive but are the sorts of parts whose collective cost adds up rapidly.

15) Begin reassembly in reverse order. Pay particular attention to carefully insert the electrical connector straight in to the cluster. This is easier to say and do--particularly if you have large hands. It's a great place for a female helper with small hands.

16) With the cluster in position, reconnect the negative battery cable and test all bulbs for operation.

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Gauge Pack:

1) While it sounds like more work, I suggest loosening the center console plate and removing the armrest behind the parking brake lever.

2) Remove the seat cushions (bottoms) or entire seats. Only four bolts for each and it makes other removal FAR easier. If you have the "high cushion" seats whose passenger side folds down level with the storage area you need some long extensions to remove the rear bolts. I'm not sure about the earlier seats.

3) Remove the carpet trim panels from each side of the center console. There are three screws in each (front, middle and rear). They just go directly into the carpet so they can be surprisingly difficult to find.

4) Remove the two screws (one each side) that hold the rear of the console plate to the parking brake frame. These are installed horizontally and point directly towards the front of the car.

5) Remove the two screws (one each side) that hold the rear of the arm rest into position.

6) Remove the armrest.

7) Remove the two screws holding the front of the console plate to the bottom of the gauge pack. These screws are nearly hidden and you may call it the most difficult part of the job. You need a stubby screwdriver. With a flashlight, look up towards the roof from the front of the console plate for two tabs (one each side) each with a screw heading roughly vertically up into the gauge pack bezel. Remove them.

8) Remove the four small bolts (two each side) holding the center console plate to the framework.

9) Relocate the console plate by pressing down slightly at the front while pulling the rear of the plate up and to the rear.

10) Remove the four screws from the gauge pack bezel. Two at the top, one on each side.

11) Look for any support bracket(s) securing the radio to framework. Remove them if found.

12) Remove the gauge pack and radio as an assembly. Be very careful not to damage the dash at the top center where the lantern assembly for the climate control illumination is located! When somewhat out disconnect the connector for the lantern, the gauge pack and two or three for the (factory) radio. If an aftermarket radio I have no idea what you have to remove.

13) Do not forget to replace the bulb for the PRNDL position indicator. Also when repositioning the be certain to engage the pin for the physical position indicator into the housing.

14) Reassembly is in reverse order. A helper for a few minutes is of great assistance when getting the center console panel back into position as it take quite a bit of forward pressure best applied from both sides at once. When reinstalling the arm rest be certain that the cover is properly attached over the tabs on the under side of the frame.

15) Particularly if you have not removed the seats but CERTAIN not to trap the seat belt connectors behind the carpet trim panels! It is amazingly easy to do so.

16) Another reason I suggest removing everything and not just the gauge pack itself is that seems to be the best way to ensure that everything goes into proper alignment while ensuring the least possible chance of breaking tabs at both the front and rear of the console plate. Broken tabs can be repaired or rebuilt but the replacements are not particularly expensive and are easily available, reasonably priced and a truly perfect fit using a plastic that perhaps exceeds the quality of the original.

 

1969 Corvette L46

I was wondering if it would be worth it to remove the steering column. Wouldn't that give you a lot more visibility and make the rear of the instrument clusters more accessible?

I'm at that point in my car.. that is why I am asking.

 

There are GREAT differences between the dash and console between a '69 and '78+

Besides having a one piece dash (instead of three? piece) in the earlier models and quite durable plastic (instead of rather unforgiving zinc "pot metal") bezels for the console and gauge pack I believe that access and ease of removal are also significant differences in the later models. My only personal experience is with my '79 but the '78 interior is essentially identical.

 

Wow .. I didn't realize that. That'a a great feature. Oh well .. I guess I'll have to remove the column.

 

Most of my dash lights are out and my light switch is going bad. Thanks for the info. This is going to be my bigger project