GM Stepper Motors [What You Need to Know]
GM (General Motors) stepper motors are among the most popular choices for DIY projects. They offer great performance when you need high torque in your applications.
Stepper motors are usually found as Fuel Gauge Stepper Motors, Speedometer, and more. ISS Automotive GM Stepper Motors are standard motors used in our instrument cluster builds.
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How long do stepper motors last?
On average stepper motors can last 20 or more years. What normally causes issues is extreme cold or hot temperatures.
This question has been asked many times by people already using or wanting to start using stepper motors. The truth is that in most cases unless you are using the motor wrong (forcing it to go past its rated torque), stepper motors can last for years.
How do I know if my stepper motor is bad?
There are several ways to determine if your stepper motor is bad. Of course, the most direct way is to test it with an ohmmeter. If you determine the resistance of your motor windings, and it is way off from what it should be, then you have a bad motor. Most likely the windings are open or the coils have burned out from a shorted condition.
Another method to check is to apply voltage and see if the motor rotates. It helps to have an RPM meter, preferably one that is remote and reads the rotation of the shaft, not just the movement of the commutator. This way you can rotate the motor with your fingers and see that it is indeed moving as you apply voltage.
You can also check for bad connections by applying a voltage to the stepper, and monitoring the voltage on the opposite terminal with a VOM or DMM. For example, if you apply 24 volts to the Green and Black wires of a unipolar motor, you should see 12 volts on the White and Red wires. If not, there is a connection between those two wires that is bad.
If you still don't know if the motor is bad, the only way to be certain is to test it with an ohmmeter.
Are all GM Stepper motors the same?
No, which is why we recommend you purchase the latest versions from ISS Automotive. You can find these in our store here ISS Automotive.
We have stepper motors for the water temperature gauge, transmission temperature gauge, speedometer, oil pressure light, and fuel gauge.
What are stepper motors good for?
Instrument panels are a good example of a place where stepper motors can be found.
Stepper motors can be used as a direct replacement for DC motors, plus they can be used for more precise position control. They are also low-cost, reliable, and easy to use.
In instrument panels, stepper motors are used for adjusting the position of displays or labels using a small number of electrical impulses. Incorporated into the driver's seat or another central place in the vehicle, they can then be used to move displays or labels into position.
As they are compact and robust, stepper motors are also sometimes used in the automotive industry. They can easily handle impacts that might harm other types of motors and are therefore well suited to use indoors or on hoods.
Click here to read: Chevy Silverado Instrument Cluster Not Working [Professional Built] >
How do stepper motor gauges work?
General Motors or GM instrument clusters are, in short, clusters of gauges that are powered by an electric stepper motor.
They are used in many GM vehicles from the mid-eighties to the mid-nineties and are found in GM Astro/Safari vans from 86 to 91.
Stepper motors work on the simple principle of electromagnetism. When an electric current passes through a wire it creates a magnetic field. This is used in the motor to create a force.
When the current is turned on and off, it causes the wire to turn. This causes the shaft of the stepper motor to turn, which causes the gauges to turn.
How do you test a stepper motor battery?
To test the gm stepper motor battery, you will need the battery itself and a meter. The stepper motor battery has two leads and a voltage rating, which you can find on the side of the battery. If using an analog multimeter, turn the dial to the 20-volt range. Then place your leads across the battery terminals and look at what number it reads out - this will be the voltage rating of your battery. If using a digital multimeter, it will display the volts read directly on the screen. In addition, you can test the battery by placing your meter leads directly between two terminals on the battery (not touching, as this could send current through you) and see if there is a voltage between the two leads. If so, then your battery cells are good; if not, one (or more) of your cells is dead.
How do you fix a stepper motor?
The stepper motor has a gearbox attached to its shaft. It is this gearbox that needs fixing when the motor does not turn as expected.
This is what you need to fix: screwdriver, spanner, and oil (engine or sewing machine).
You can fix the gearbox by following these steps:
Unplug the stepper motor from the power supply. Take apart the back cover of the motor. The back cover is the one opposite the shaft. Use a screwdriver to remove any screws if they are present.
Pull apart the case of the motor. Try to open the cover gently so that it will not break into pieces. Remove metal bushings or any other parts that are present inside.
Clean any metal dust or dirt that is stuck in the gearbox using oil. Make sure all metal parts inside the motor are cleaned by removing all the metal dust. Use a cloth to wipe off the excess oil. Put back all parts and cover in their position at the same time making sure that no pieces are left out.
Make sure that the motor shaft turns smoothly after reassembling it. Check if all gears are moving freely. Put back the motor's cover if it is not already in place. Make sure that there are no loose parts on the cover.
Check for the power supply and the motor's cables. Make sure that all parts are connected properly. Plugin the stepper motor into a power source. Let the motor run for 1 minute to check if it is working.
Click here to read: Cost of Instrument Cluster Repair >
Can stepper motors be repaired?
Stepper motors can be repaired in some instances. If this is about the speedometer gauge of a vehicle, it's pretty unlikely that a simple repair will be possible.
However, if it's used for another function and has reached its life cycle it is quite possible that a repair can be performed. Just replace the old one with a new, identical stepper motor.
How do I choose a stepper motor for an application?
The most essential factor to consider is the wattage requirement of the stepper motors. The total power required is measured in watts or kilowatts (kW). It is the amount of work required of a motor at its rated torque output.
A motor with higher wattage means it is capable of providing more torque. For example, if you need to drive a heavy load, choose a high-power motor.
For a vehicle gauge calibration application, choose one with a wattage of about 1/2 to 3/4 of the load weight.
What is a gauge stepper motor?
A gauge stepper motor is a small electric motor with 8 or more wire coils used to drive the gauge needles on truck instrument clusters or instrument panels.
It receives power from the instrument cluster to drive its needle. The motor has an input signal from the engine computer and it turns on and off accordingly. The input pulse causes the motor to rotate at a specific angle which moves the needle for an accurate reading.
Where can you purchase a gauge stepper?
You can shop for new or used gauge stepper motors from many online stores. You can also purchase a gauge stepper motors repair kit. The repair kit includes the needed tool and instructions on how to remove and replace a damaged needle.
How do you measure stepper motor step size?
The step size can be measured by counting how many times the stepper motor rotates as the shaft is rotated through 360 degrees. This value is nominal and will vary from engine to motor, +/- 5% or more is common.
Are instrument panels and instrument clusters the same thing?
The terms instrument panel and instrument cluster are sometimes used interchangeably, but the proper terminology is "instrument cluster". Instrument panels are part of the interior trim while instrument clusters are the gauges and information displays.
GM instrument cluster repair
The instrument cluster is used for displaying information to the driver of the vehicle. It is connected by a variety of wires to various components in the engine bay, inside the car or truck, and under the dash. These wires and connectors carry critical control and signal lines, so if they become damaged by heat, corrosion, or wear it can affect the operation of the vehicle.
The GM instrument dashboard consists of 2 main parts. A display panel with electronic gauges and an inner bezel that holds the speedometer, fuel, tachometer, etc.
The instrument uses a serial data link to communicate with the vehicle's powertrain control module (PCM). This is useful because it allows information such as speed and engine RPM to be displayed on the cluster. It also allows the PCM to monitor fault codes, and diagnostic trouble codes (DTCs), and clear them when they are no longer an issue.
The instrument can be removed from the car or truck for repair, replacement, or restoration. Restoration is simply restoring the cluster to its original condition by replacing burned-out lights with new ones. Instrument clusters are often removed when they no longer work properly. This may be due to age, electrical problems, or corrosion at the connectors.
Common symptoms of a faulty GM instrument are:
* Brightness/illumination problems
* Dim light bulbs
* Lights stay on
* Dead pixels
* Gauges like speedometer, odometer, tach, or oil pressure gauge not working
* RPM needle jumps or is erratic
* Speedometer reads high or low, especially at high speeds
* Malfunction indicator lamp (MIL) or check engine light (CEL) is illuminated
* Temperature and oil pressure needles don't move
* ABS/traction control warning light
* Circuit board problems
* LCD display problems
* Speedometer needle jumps between 0-10 MPH during operation
* Cluster missing pixels, black spots in the display
* Corroded circuit board
If you suspect that your instrument or gauge cluster is experiencing any of the above symptoms it could be failing. Before you replace the whole cluster I would recommend that you check and see if it can be repaired.