Boom truck Hydraulic system question

Hi guys, first time poster here. Thank you in advance for any help you may give me.
We have a 2008 F350 with an Altec AT200A Boom lift. We have been having problems with the boom system not getting “power”. Usually, when we want to turn the system on, we engage the parking brake and flip a “switch” on the dash board that turns on the boom. I’m guessing it actually turns on the hydraulic pump or the PTO but I do not know too much about vehicles.
Now, the switch gets turned on, but nothing happens. The switch is lit which indicates it is “on” but I don’t hear the pump turning on. I don’t know if I should check for a fuse or if this is something else.
Ask any questions if I failed to give all pertinent info.

This is CarTalk, right?

Not really the place for this but I’d be looking for a relay. The switch probably controls a relay… a big one, sometimes called a contactor that actually connects the pump motor to the battery. Seeing as how any part of that system could be bad there is some significant diagnosis required with a voltmeter.

Maybe you should seek a professional?

When you flip the switch, if it in the cab, then in all likelyhood, the switch is only activating a relay. Automakers do not like high amperage going through the cab. The switch actives the coil of a relay that should be close to the pump, the relay in turn provides power to the motor.

The fact that the light comes on indicates that current is flowing through the switch and the coil of the relay. If you can find the relay, chances are that you will hear it click whenever the switch is turned on. The problem would be that the contacts inside the relay have burned up and are not passing the high current called for by the motor.

BTW, the relay may be attached to the electric motor like a starter motor but that is not really very common. The large wire attached to the terminal on the motor will lead back to the relay. There maybe two wires, one will just go to the chassis or body of the truck.

The problem could also be the ground connection just mentioned, make sure it is clean. The problem could also be the motor. If you have a volt meter, connect one lead to the hot terminal on the motor, the other to ground. Have someone flip the switch. If you get no voltage, it’s the relay. If you get full voltage, it is either the motor or the ground connection. If there is a ground lead, put the + lead of the meter to the ground terminal and if you get voltage, it is the groound, if not, the motor needs work.

The motor may just need new brushes, that is their most common failure.

Edit: there could be an inline fuse to the motor. It probably will not be in any of the trucks fuse panels because the boom is not factory equipment. If the boom has a control panel, the fuse would most likely be found there. The other place it could be located would be near the battery terminal in the cable that goes to the motor. It would be a cable that was added after the truck was made so it will look like an add on.

Seeing all you have to do to activate this system flip a switch, I’m guessing you have a belt driven pump with an electric clutch, (like an air condition has)

Is the drive belt there?

yes I see the “drive” on top of the motor. It is tied into the serpentine belt (which was just replaced) so I know that item is working as it should (I hope)

Thanks for the info. The Altec control panel is located in back of drivers seat. When I took the cover off to see what it looked like I saw the fuses and connections. So I will test the “main power” wires coming into the board and see what I get there

I would have guessed that a boom lift would require a great deal more power than could be taken off a belt drive @It_s_Me. But the most recent model that I had hands on experience with was pre 1990 and things may have changed since then. Those Harley belt drives seem to hold up OK.