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Solenoid Testing 2.0

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Solenoid Testing 2.0

Postby Cart Doctor » Tue Aug 15, 2006 9:46 am

Solenoid Testing

Next to batteries the most misunderstood part of a gas/electric Buggy is the solenoid! A solenoid is nothing more than an electric switch. The sole purpose is to make and break a circuit on demand. You can also term the solenoid as a contactor. Switches are normally a mechanical operated device such as a light switch, key switch or any type that requires manual or mechanical activation. Solenoids are electrically activated by an external input (voltage). We call this the activation (control) circuit or primary circuit. In this primary circuit you have the activation wiring and the internal primary coil. The primary coil requires two potentials for it to activate (positive and negative). Most Buggies activate the solenoid with battery pack voltage, however, be aware that some older Buggies use tapped voltage and the solenoid must be matched to that voltage tap. Taps are different connecting points on the battery pack. Make sure you are working with the correct wiring diagram per the application. The secondary circuit (power circuit) consisting of large power contacts on the large connecting posts will carry the heavy loads created by the motor or starter/generator. For convenience of this writing we have numbered the connection points with 1 though 4 for identification purposes only.


Notice in the picture some other items that may or may not be on your Buggy (diode and resister). Not all applications use the diode and resister, that is why it is important to determine the year, make and model of your Buggy. The diodes function is to catch spikes in the primary circuit. The resister (250 ohm) is used to pre charge the capacitor bank in the controller (if using this system). The resister will connect to the large solenoid terminals. Again, work with the correct diagram for the system you are working on.

Now let?s talk trouble shooting!

1) The car will not run.
A) Does the solenoid make a ?clicking sound?? If it does not we first must determine if activation voltage is present at the small terminals #1 and #2. Connect a volt meter across the connections at #1 and #2 and activate the system. In other words put the car in the run mode, key switch on, car in forward and the accelerator pedal pushed. If you read system voltage 12/24/ 36/48 and the solenoid does not ?click? the solenoid is defective and will need to be replaced.

Make the connection just like this.

B) The solenoid does not ?click? and you do not read system voltage. This tells us that one of the voltage potentials is missing at connection #1 and or #2. To find out which potential is missing leave the red lead of the volt meter connected to Pin #2 positive connection (usually a blue or red wire). Again colors vary and make sure by using the correct diagram for the make and year of car. Place the black lead of the volt meter to battery negative at number six battery. Activate the system and if you read 12/24/ 36/48 volts the positive input is correct. This means the key switch, micro switches and wiring is good and you are missing the negative input.

Positive connection at terminal #2.

Now place the black negative lead from the volt meter to terminal #1 and connect the red lead of the volt meter to battery #1 positive connection. Activate the system and again if you are not reading 12/24/ 36/48 volts you have confirmed that battery negative is missing. Again depending on the system the Buggy is using the missing negative will need to be traced to its source. Some systems supply the negative from a controller output or with some Club Cars the computer. Most gas cars use ?frame? ground. Electric cars do not use a frame ?ground?. You can determine this by the use of the correct wiring diagram.

Negative connection at terminal #1.

So let?s say that we were missing the positive at connection number 2. This means either the key switch, micro switch and or accelerator switch is open or out of adjustment. NOTE: Be aware that some carts uses the key circuit as a negative circuit and adjust accordingly as per the correct wiring diagram. You will need to trace voltage to each individual component in that circuit and determine where the voltage is lost. If your cart uses the diode, make sure you make the proper connections as the diode is polarity sensitive!

Secondary Circuit (power)

1) The solenoid does ?click? and the cart will not run. Disconnect cable #4 and lay it aside or tape it so it does not touch anything. Cable 4 will be the load side of the solenoid that connects to the controller/motor circuit. If the cart uses a 250 ohm resister, remove and tape the end of that as well.


2) Place the positive lead of the volt meter on the vacated #4 terminal. Place the negative lead of the volt meter to battery #6 negative. Activate the system. If you do not read 12/24/ 36/48 volts the secondary contacts are defective and the solenoid will need replacing. If you read 12/24/ 36/48 volts the problem is some where in the controller, motor, wiring/cables, shifter and or input control such as an inductive throttle sensor, potentiometer or v-glide.

3) Solenoid does not ?click? but runs all the time with the key on or off. Connect the ohm meter as per step number two. If you read 12/24/ 36/48 volts with out pushing the accelerator pedal and key off the solenoid is defective. This means the secondary contacts are stuck in the on position.


1) Raise the rear wheels off the ground and use the proper support stands.
2) Disconnect the battery/battery pack when required for testing. If the Buggy is a regenerative system place the run/tow switch in the tow position before disconnecting the batteries.
3) If you have a proclivity of being a pyromaniac, make sure you know where the closest fire extinguisher is!
4) Use caution with the higher voltage Buggy?s as severe burns can occur by shorting out connections with a tool.
5) Use caution around the batteries as hydrogen gas can be present. Keep flames and sparks away from the battery compartment. Keep battery acid from your skin and eyes as this can be a irritant.

There you have it! The solenoid is not some complicated mystery. Just think of it as just any other switch you may encounter that it is electrically activated.
Cart Doctor
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