Sorry – no pics. My son had my camera out of town on a Boy Scout event. When time permits I will take an hour and do pics for this article.
The pointers on the gauges in the instrument cluster are operated by stepper motors, which are driven by the cluster logic. For more info on stepper motors see the Wikipedia article
http://en.wikipedia.org/wiki/Stepper_motor . The stepper motors are a common failure. My oil pressure gauge went erratic then stopped at the high end even with the engine off. A scan tool told me the sensor was working and the PCM knew the real oil pressure; this narrowed things down.
When this happens you have some choices:
1. The Dealer Man wanted over $500 for a new cluster with R&R and programming the cluster with vehicle mileage and engine hours.
2. There are some people advertising cluster repair on eBay. This requires pulling your cluster, shipping it, getting it repaired, then shipping it back. I have been told the truck will run fine without the cluster, but then you get to guess things like speed and what gear you are in.
3. Replace the bad stepper motor yourself. I got one on eBay for $15 plus shipping from charlieboats08.
Materials:
1. One or more stepper motors.
2. Fine rosin core solder
Tools:
1. Desoldering tool. There are several types. Some are “suckers” that you use with a soldering iron to pull the solder out of the joint. The one I used is from Radio Shack for about $11. It is a 45 watt soldering iron with a hole in the tip and a rubber sucker bulb.
2. Soldering iron. About 25 watts is good for this job.
3. 7 mm nut driver or equivalent.
4. A small flat blade screwdriver.
5. A kitchen fork. (yes, details later).
Procedure:
1. Set the parking brake. If it doesn’t work, block a wheel.
2. Turn the key on and pull the shift down to “1”. Chime goes “ding ding …”
3. Pull the tilt wheel all the way down.
4. Pull off the dash bezel. It uses spring retainers so pull it straight back.
5. Take out the 4 screws (7 mm head) that hold the cluster in.
6. Work the cluster back. Release the electrical connector at the top back of the cluster by releasing the retainer. Unplug the connector.
7. Remove the cluster. It’s a bit of a squeeze between the top of the dash and the shroud thing on the steering, but it will come out without breaking anything. Honest.
8. Take the cluster to your clean, well lit work space. Plug in the desoldering tool and soldering iron to heat up.
9. Take the back off the (black) cluster by using your small screw driver releasing the lock tabs that hold it to the (white) frame part. You are now looking at the back of the cluster PC board.
10. Take off the front lens/bezel assembly. It has lock tabs at the top and bottom to hold it to the white part. The top ones are easy with a small screw driver. The bottom ones are a bit of a bitch. Mild cursing helps.
11. The PC board is now being held in by the gauge needles. You have to remove all the needles even if you are only working one stepper motor. The guy who sold me the stepper motor provided directions to get the needles back on pointed to the right reading but I got it wrong. More later.
12. Twist each needle a little counter clockwise to break the bond between the needle and the stepper motor. Use the kitchen fork to lift off the needle. No need for a 10 ton porta-power.
13. The circuit board will now come out. Be REALLY SURE you pull the stepper motor you want to replace. Maybe mark it with a Sharpie.
14. There are 4 pins that come out of the back of the stepper motor and are soldered into the PC board. Take your now hot desoldering tool, squeeze the bulb while NOT pointed at the PC board. (We want suck, not blow.) Melt the solder and suck it up. Repeat for each of the 4 pins.
15. The motor should now be easy to pull off.
16. Put the new motor in its place. There are locator pins. Make sure it is flush against the PC board.
17. Take your soldering iron. Make sure the tip is clean and tinned. Solder each pin to the PC board. Heat the board pad and the wire; then let those parts melt the solder. Don’t try to melt the solder on the iron then try to dab it in. That doesn’t work.
18. Examine your solder joints carefully. They should be smooth and shiny, flowed onto the pad and the wire.
19. Unplug your soldering iron and desoldering tool. If you are lucky they will cool off before you accidentally grab the wrong end of one.
20. Place the PC board back in the middle (white plastic) frame. Put the back cover on, press the retainers down until they lock.
21. Replace the instrument needles. The guy that sold me the stepper motor recommended pushing the needle on pointing at mid scale, then twisting to the bottom of the scale. Try it, but this didn’t work out for me; maybe I didn’t understand correctly. Hence:
22. DO NOT PUT THE FRONT LENS PART ON YET. More later.
23. Put the cluster (less the front lens) back in the truck, with the cable plugged in. Don’t put in the screws yet.
24. Start the truck. Oh, shyte, no start. Oh, I’m in first gear. Neutral safety switch. Put it in park and really start it this time. Watch the gauges come to life. In my case some were reading really whack.
25. Shut off the truck. For each gauge that is not reading bottom of scale, pull the needle off and put it back in pointing at bottom of scale. Repeat this step a few times until you have it all right.
26. NOW put the front lens back on your cluster. You can do this with the back part of the cluster in the dash. Push until the locks click.
27. Put back the 4 retaining screws and the dash bezel.
28. Take the $500 you just saved and buy something you really wanted.