Six Step Solution to Ensure Proper Pump and Motor Power

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When checking for any potential voltage issue, we find the best place to start is at the batteries.  

We first verify that while operating the liftgate there is a constant 12 volt source supplying voltage. During this step, we usually keep the vehicle responsible for charging the liftgate running to supply voltage. As always, it’s important to consult the manufacturer for the specific unit’s expected voltage and adhere to any local laws or idle restrictions.

The solution to many of our roadcalls is often a little bit of voltage and a running truck.

Testing the batteries to make sure they are receiving proper voltage is usually our next step.  

At this stage, we check the vehicle is putting out the proper voltage. Refer to the manufacturers charging specifications for the vehicle’s specific voltage.  

After that, we ensure the alternator charging systems put out the approximate voltage specified by the manufacturer. That voltage should be sent right back to the batteries!

If the expected voltage to the batteries is not received, we have the vehicle’s charging system fully inspected for part failure because there could be an issue with the alternator/generator (unit depending), batteries, circuit breaker, or other inline charging components.

We check the charging and ground cables for signs of rubbing, cuts, and hardness. Rubbing can cut through the sheathing and cause corrosion.

If the cables are flexed and seem stiff and/or crackle when flexed, there may be rot inside that can cause voltage drops and what may seem to be, part failure. Checking all cable connections for corrosion and tightness will help further identify the problem. We make sure that neither rotted red wiring at the connections, nor the glowing green hue of corrosion and rot dust, are present.

We check the circuit breakers under-side too!  

Many times the circuit breaker looks good where the connections are, but when flipped over, the green forest of rot shows itself! That could be a sign of voltage loss. At this point, we usually clean the component or replace it depending on the circumstances.  

Next, we follow the cable to the liftgate’s solenoid and test for proper power at the “input” post on the motor solenoid.  

We check that the vehicle is supplying the specified voltage according to the manufacturer. Usually, there is only a 0.2 to 0.3 voltage drop from the batteries to the solenoid while the liftgate is not in use. If there is a greater loss than 0.3 from battery to breaker, or breaker to solenoid, we check the cables and connections between them, then repair as necessary.  

For the final supply test, we test the solenoid’s expected output. This can take two people if we’re teaching someone that’s not familiar with the process.

With the truck running, we usually have someone operate the switch and test the motor solenoid “output” side for voltage. If the unit is running, we usually press the switch to allow the motor solenoid to “click.” If it “clicks,” no voltage comes out, and the proper input voltage has been verified, then the solenoid is most likely a bad or failed part.

If voltage does come out, we take note of the rate. We find that it’s normal to see a larger voltage drop while operating the motor. Our team considers proper voltage as having no less than 12.3 volts going to the motor from the solenoid. If the voltage is below the 12.3v while in operation, and we have already checked and tested the other components, the motor may be bad causing a high amperage and voltage draw. We then, VERY carefully, measure the motor casing for heat (VERY carefully). If it is getting too hot, that could be a sign of internal resistance. At this point, it is likely that the motor needs to be replaced.

As our disclaimer notes, information on our site is not a substitute for the professional advice of a mechanic who has personally inspected your specific situation and because every situation varies we cannot assist with troubleshooting or advising. ALWAYS consult a professional.

We only sell new OEM products to help you in your diagnostics and repairs so please contact us with your liftgate’s serial number, model, and item description and we’ll help get you back on the road!

Thoughts? Let us know.  

Need parts? We’re an email or call away (seriously).

Talk soon,

Your Team at LiftGateMe

Please see the disclaimer at the top of this article.