12V motor lost force

[Anthony5]

Not sure this belongs here, so delete if off topic.

 

I have an electrical powered trunk lid on my truck. It has 4 electric motors, and since a few days it isn't able to get the back side down on it's own force.

 

However the motors still work, because it has several of those gas struts to "help" the motors, and if I remove those that support the upward movement, the lid will go down. But of course than I'll have to give it a hand to get up again.

 

Went to a shop that installs those lids, and without any testing he said motor no good, 5000 Baht for 2 new motors.

 

So my question is, since the motors clearly still work in both directions, is it possible that they lose the potency?

 

Could this may be fixed more cheaply by replacing the brushes, or is replacing the motor the only solution?

[Strange]

These motors run of the trucks electrical supply? Is there any difference in the strength of the motor when the truck is idling/running?

 

Another thing to help diagnose is bring the truck RPM over about 1800 and hold it there, and try it. 1800 RPM is about where the alternator starts to generate full power. 

 

This would provide some more info. 

 

Also the gas strut things might need a little lubrication on the shiny ram part. A little motor oil on a paper towel and give it another try. 

 

How old is the kit? 

[Anthony5]

Kit is 5 years old, and accelerating the engine doesn't make a difference.

 

There are a total of 6 gas struts, 2 vertical in the front, 2 vertical in the rear and 2 horizontal in the rear, which I consider are to support the lowering of the backside.

 

I removed all struts and they work properly, but the 2 horizontal ones don't have any pressure, and can be easily moved by hand.

 

So I thought that was the issue and went to buy new ones, but when I checked the new ones also have no pressure, as they are even pressed down in the package.

 

So the gas struts are not the cause.

[Strange]

Well if the gas struts are not the cause, and you have no change with trying it at RPM, and you know for a fact that there is not a voltage/power problem, and there is no restriction in the system and nothing is in a bind and everything is lubricated, then yeah its got to be the little motors. 

 

To answer your question, yes little cheapie 12v motors lose their 'potency' after a while. Same as the little 12v motors that roll the windows up and down. They get old. I have no idea about 'overhauling' the motors. Maybe someone else can help with that. 

 

5K for 2 12v motors sounds crazy expensive though I would think 5K for a whole set. Gotta be easily sourced online? 

 

[Anthony5]

I don't think they can be easily sourced online, since the mounting etc will be specific to the lid I have, but 5000 was indeed a rip off from the well known car accessory shop in North Pattaya.

 

I made a phone call to a dealer that installs the same brand of lids in Bangkok and he told me they are 1500 Baht a piece.

 

Still interested to know if they can be refurbished.

[Strange]

Dunno about the refurbished thing, but I would be willing to bet the motors are not 'made for your kit'. It would be the other way around. I could be wrong but thats usually how it works with stuff like this. The motors should have a serial number or casting number or something on them you could google if you felt like it. 

 

Anyway 1500 each id just replace them and get another 5 years out of it. Hell by that time it will be time for a new truck. 

 

Hopefully someone else can help with the refurbishing. 

[Crossy]

As noted above the motors are likely a standard unit, can you post a photo including any rating plates if they have them.

 

I'll put money on worn / stuck brushes which ought to be an easy fix.

 

Can you check the voltage at the motors when they're operating, it could be a duff limit switch.

 

[Anthony5]

5 hours ago, Crossy said:

As noted above the motors are likely a standard unit, can you post a photo including any rating plates if they have them.

 

I'll put money on worn / stuck brushes which ought to be an easy fix.

 

Can you check the voltage at the motors when they're operating, it could be a duff limit switch.

 

 

The voltage at both motors measures about 7.5V during operation. When the movement is stuck the voltage drops to 3.5V. No rating plates on the motor other than the sticker of the Super Up company.

 

 

[Anthony5]

I also measured the front motors and in upward movement, when they are supported by the struts, they measure 12V. On downwards movement, when much more power is needed, they measure 7.5V.

[sirmud63]

you may have a connection problem . terminals or wirering .check for loose or coroded conections .

[Crossy]

3 minutes ago, sirmud63 said:

you may have a connection problem . terminals or wirering .check for loose or coroded conections .

 

Yeah, those voltages do look low, worth looking for corroded connections (check the ground to the chassis).

 

[Anthony5]

Where should I look for those ground connections, as I see only 2 wires coming from the motor.

 

Since the voltage with no load is 12V, would dat not indicate that connections are good?

[sirmud63]

4 minutes ago, Anthony5 said:

Where should I look for those ground connections, as I see only 2 wires coming from the motor.

 

Since the voltage with no load is 12V, would dat not indicate that connections are good?

nop. it only shows up under load . trace the wirering harness back as far as you can ,you will find an earth somwere. also feel for any hot or warm conections just after you have operated it . there will be your problem .

like most auto electrical faults , its just a prossess of elimination . once you figure it isnt that ,you look for somthing else .

 

Edited November 22, 2016 by sirmud63

[Anthony5]

47 minutes ago, sirmud63 said:

nop. it only shows up under load . trace the wirering harness back as far as you can ,you will find an earth somwere. also feel for any hot or warm conections just after you have operated it . there will be your problem .

like most auto electrical faults , its just a prossess of elimination . once you figure it isnt that ,you look for somthing else .

 

 

May I take it that you're confident, from the details I posted,  that the motors don't need replacing, but that the fault definitely is somewhere else?

[sirmud63]

53 minutes ago, Anthony5 said:

 

May I take it that you're confident, from the details I posted,  that the motors don't need replacing, but that the fault definitely is somewhere else?

not certain , but more than likly. not with out looking at it personally. it could be many things . like i said ,its a prossess of elimination . if you have a mullty meter ,test the wirering for resistance.if it checks out ok ,it could be the motors. no point in replacing the motors just to find the problem still exists .

Edited November 22, 2016 by sirmud63

[Strange]

12 hours ago, Anthony5 said:

The voltage at both motors measures about 7.5V during operation. When the movement is stuck the voltage drops to 3.5V. No rating plates on the motor other than the sticker of the Super Up company.

 

Those motors look just like bog standard power window motors FYI

[Strange]

10 hours ago, Anthony5 said:

May I take it that you're confident, from the details I posted,  that the motors don't need replacing, but that the fault definitely is somewhere else?

 

Its always worth a shot to chase your wiring connections and have a look. 

 

11 hours ago, Anthony5 said:

I also measured the front motors and in upward movement, when they are supported by the struts, they measure 12V. On downwards movement, when much more power is needed, they measure 7.5V.

 

The 2 wires coming from the motor have to go to a switch that will reverse the polarity so the motor can change directions. That switch might be old and have resistance. 

[Anthony5]

There are 2 sets of switches, actually 3 if I include the keylock on the lid itself, one set inside the car and another set under the lid.

 

Both behave the same. I haven't tried the keylock, as I have no idea where the key is, because that one operates the 4 motors simultaneously.

 

May have a look for the key tomorrow.

[Strange]

6 hours ago, Anthony5 said:

There are 2 sets of switches, actually 3 if I include the keylock on the lid itself, one set inside the car and another set under the lid.

 

Did a little surfing through the Power Up website and google images. Kit is a little more 'complicated' than I originally thought. 4 power window motors, 2 manual switches, and a remote key fob. The way that is wired up is hard to diagnose without being there with a DVOM.  The system is exactly the same as car windows and a car window switch (drivers side) usually has about 20+++ wires going into and out of it for changing polarity for 4 separate windows & 4 separate controls. 

 

Anyway the motors are just regular old power window motors. 1500 baht each is about right assuming thats fitted. Otherwise it would be super easy to just buy replacement motors online or at an auto shop. Just take a motor in and compare to stuff they have in stock. 

 

Aliexpress has junk too just have to wait for it to come from china. Just takes some figuring because they are either "Left" or "Right"

 

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