This 2005 GMC Sierra came in with the complaint that the speedometer does not work. In fact it was stuck at 55 mph when it was sitting in the shop key on engine off. This repair can apply to any one of up to seven gauges on 2003 through 2007 Classic series Cadillac, Chevrolet and GMC full sized trucks and SUV’s.
I went ahead and took some pictures of the remaining gauges while the engine was running and fully warmed up. this gives a point of reference for the gauge positions in case something goes wrong when replacing the gauge stepper motors.
Obviously the instrument cluster will need to be removed to replace the faulty stepper motor. I started by switching the ignition on, dropping the shifter all the way down into D1, tilting the column fully down and holding the brake.
Grasp the edge of the instrument cluster trim panel and pull it loose form the dash. Repeat the pulling process all the way around the outside edge of the panel.
Roll the top of the panel out and depress the panel down slightly to finish removing the trim panel.
There are four 7 mm headed screws that hold the instrument cluster in place. One in each corner. With the screws removed pull the cluster out far enough to unplug the harness connector. Make sure the key if off when disconnecting the harness.
Now that the cluster assembly is removed the front cover has to be removed. There are several clips that hold it in place the upper ones are easy to unhook. The two lower ones shown in the next picture can be difficult sometimes. Remember to use a gentle touch.
Now that the lens cover is removed the gauge needles need to be rotated fully counterclockwise until they stop. Again a gentle touch. Using masking tape mark the lowest position of the needle. The faulty gauge will need a slight bit more force to move it. About the same force needed to click on your mouse.
The faulty speedometer gauge needle moved fully counterclockwise to it’s stop position.
All of the gauge needles moved to their respective stops and marked with masking tape.
Move the needle past its stop to loosen the grip between the needle and the motor shaft.
Now breakout the super sophisticated special tool to remove the needle from the stepper motor shaft.
It is best to slide the fork through enough to be able to grab the other end and pull straight up. In particular if you are planning to reuse the old stepper motor. Also if you are only replacing the faulty stepper motors, I do not recommend turning the needles to break them loose from the shafts on the working gauges.
The underside of the needle.
Now the remaining two halves of the instrument cluster assembly can be separated.
There are clips along the edge of the black plastic cover that have to be released.
Make sure you leave this cover in place until the needle positions are marked and the needles have been removed.
If you remove the rear cover before the needle position is marked you can wind up with this much disparity between where the tape and the needles are actually positioned. Ask me how I know this?
This and most of these trucks have six gauges. If there was a transmission temperature gauge it would have been in the lower left corner.
Now the fun begins. You must use a small but hot soldering iron to melt the solder and remove the stepper motors. I use the tip to straighten out the four leads after the solder is softened.
I also hold the motor as shown below and keep constant pressure against the circuit board. Then it is a matter of switching back and forth between the four leads to remove the motor. There are all sorts of devices to aid in the removal of the solder but I prefer to remove the motor in this fashion and then use the tip of the soldering iron and sometimes a small wire to open up the holes.
Well I have installed new stepper motors for all six gauges in this instrument cluster and it is time to put it all back together. Because I have a scan tool that can read instrument cluster data I take the extra step of making sure the gauges reflect the digital data.
I put it all back together and this one is done.
As Anonymous stated BE VERY CAREFUL and CONSULT the correct wiring diagram for your vehicle before trying.
Great writeup, but for those without a scantool you can test and calibrate the gauges with just a bench power supply.
If you apply 12V to the right pins (consult a proper wiring diagram and BE CAREFUL!), the cluster will power up and zero out the gauges.
On a 2003-2006 Truck cluster, the pins you need are B12-GND, B11-B+, B9-IGN. To test the illumination, it’s A12-GND and A11-B+.
To test the motors, I move the gauges up near the max manually, then power the cluster up. A good motor will bottom out past zero, then zero out. A bad motor will not zero out, but will just step a few degrees and stop.
This can also be used to check that the needles are on right, I rarely mark them anymore because when they are adjusted to the zero lines, I have found them to be pretty accurate.
Hope this helps some of you.
Almost anything made by man can be rebuilt but I do not know of anyone doing so with the mode actuators.
Fisherman, do you know if the blend actuators can be rebuilt?
Just did the full stepper motor replacement to my 2004 GMC Sierra 1500 cluster. Not a problem at all. Had it out and back in in under an hour, and I’m a novice. I recommend a descent soldering iron and a solder sucker…very handy indeed.