Saturday, June 26, 2010

Part 2: Fixing Dash Lights on a Late Model GM Vehicle (Out of Warranty).

This bears repeating, I do not have control over what you're working on, how you're working on it, or what your working with. There are risks to fixing anything and you assume all risks involved. Even if you're careful, stuff happens and you could cause personal injury or property damage. When in doubt, call a professional...

You may be tempted to buy a junkyard piece and be done with it, but the chance of getting one with same options as your vehicle are slim and getting one with the correct mileage is nil. The former is for functional reasons (who wants a tire pressure warning light when your car doesn't even have the option?) and the latter for legal reasons. Odometer fraud is a federal crime and any discrepancies MUST be declared on the title. This WILL reduce the value of your vehicle unless you plan on junking it in the near future. Extended warranties usually won't cover speedometer faults and certainly not bulb changes. So your options are limited. What to do.

My choice was to dig in and fix this, carefully.

There are eight light bulbs that need to be changed to get the instrument panel lit again. This does not count the bulbs for the idiot lights that wear infrequently. This is going to be helpful for the next step. Radio Shack is still the best place to get parts for electronics, but inevitably, they will not have the 12 incandescent bulbs this cluster has. As it was, I cleaned out every one they had and I had to do some digging. The ones preferred are the 12 volt - 50 miliamp Bi-pin lamps (#272-1154). You can use the 12 volt ones with the hookup leads, but these are a pain in the tuckus and you WILL break at least one trying to prepare it. Get the Bi-Pins bulbs, you'll be glad you did. You will also need a 15 watt soldering iron (no higher) and a roll of .032" 60/40 rosin core solder (not acid core)

The instrument cluster's held together with tabs that snap on like the edges of a tote. First remove the lens and set it aside. This is where it gets tricky. The needles need to come off and they are not intuitive or indexed. It would be good to mark their positions on the dial with a grease pencil (do not use a marker or paint) or your readings will be inaccurate. There are tools to remove these, but a regular fork placed under the needles where they attach to the stepper motors will suffice. Lift up gently on the needles with the fork to remove them.

Unsnap the back of the cluster and you'll see the printed circuit that lives inside. A word of caution here and this is one reason why this is risky. You need to work where you can ground yourself to protect against static electricity, which will destroy a circuit board. The best place is in the kitchen where you can at least touch the faucet.

One either side of each stepper motor, there lives a bulb and these are not unlike Christmas tree (not holiday tree) bulbs in their form factor. The difference is that the Xmas tree bulbs are too tall to fit. The bulbs sit on ceramic holders with each lead into a solder joint. twist the bulb and holder off the board. As there are four solder joints under the holder, pay attention to the ones the leads go into and they are larger, so that will help.

Take your bi-pin bulb and carefully, with pliers, bend out the pins at a 90 degree angle so they can sit in the solder. The rest of the job is going to be soldering in each bulb so they stand upright and and not burning up the circuit board, or your appendages. The bulbs with the wire leads will have to be installed like the originals and these are tricky. I cannot teach a person how to solder parts together in this post. This is something I've been doing since I was ten years old, tomorrow I turn 40. This is not the part to practice your skills on either.

One you get the bulbs in and you're satisfied they're in securely. put the dash together, making sure the stepper motors are at their lowest limits AND and the needles are in their original positions (HINT these are not going to point below the marks until you actually hook the cluster up, but some adjustment is to be expected. BE careful or you will compromise the accuracy of the speedometer and may to use a GPS to set it straight. If the job's done with care, you'll have your dash lights for less than $20.00 for about an hour's worth of work. Compare this to being without your car for several days and paying the dealer five bills. Maranatha!

No comments: