My new Knight Hauler/Freightliner

[540-MAN]

Still looking for parts in the above post.

[thebat]

looks great so far hey can i ask you to get me the part numbers for the tail light pods and the lenses for the rear and the cwenter reverse lamp set id like to put them on my king hauler thanks.

[540-MAN]

I'm having a problem with my truck now so I hope somebody can help me with it.

I gave it a test run the other day and everytime I put it in third gear with trailer on and the stick is flat out on the radio it shuts the truck down. Then when I take the trailer off it seems to run fine with out any problems.

I have checked all the wiring to make sure everything is connected and even fully charged the batteries but still no change so it has got me stumped of what is wrong with it.

Has anybody got any ideas of what it might be?

[mavrick0]

Sounds as if you are overheating the ESC and it is going into thermal protection mode and shutting things down. Without the trailer there isn't the load on the ESC so there is no reason for it overheat. Not knowing what trailer you are running I'm going to assume it's probably heavier then the stock Tamiya trailer. One suggestion would be to change the pinion on the motor and drop it down a tooth or two or try going to a crawler motor that has more torque for pulling but not as fast as the stock motor.

[Stuff]

are you running an MFC?

the other day I jammed mine into 2nd and it caught funny and shut down the truck. Maybe check the tranny to make sure you have 3rd assembled right? only thing i can think of.

[540-MAN]

Yes I am running a mfc unit in my truck and it is installed the same way as my old one I had. The tranny is all ok and put together as per instructions. I have no idea what is going on. The receiver doesn't have a Ariel on it where the other trucks I had did so I'm just wondering whether it maybe coursed by this or not as the cab might be blocking connection.

[Backlash]

Have you got the little limit switch connected up under the 5th wheel?

Have you got another battery to try?

What exactly happens when it shuts down in top gear? Do you just lose drive, or do you lose everything (i.e. no steering, drive or gearshift)

Does it happen as soon as you select top gear, or can you drive it for a while?

What do you need to do to reset the truck..? Is it just a matter of selecting 1st or second gear or removing the trailer, or do you have to turn it off, and then back on to get it to go again?

Is your radio 2.4GHz, or crystal type (27MHz, 29Mhz or 40Mhz)??

Have you used this radio with the MFC before?

Is it an MFC01 or MFC03?

[540-MAN]

Originally Posted by Backlash

Have you got the little limit switch connected up under the 5th wheel?

The 5th wheel switch is locked on all the time with or without trailer.

Have you got another battery to try?

I have 2 batteries and they are near new.

What exactly happens when it shuts down in top gear? Do you just lose drive, or do you lose everything (i.e. no steering, drive or gearshift)

When it's in top gear the whole thing shuts down like it does when the battery is flat and starts up again.

Does it happen as soon as you select top gear, or can you drive it for a while?

If the stick on radio is half throttle it runs fine but as soon as the stick on the radio is flat out it shuts down.

What do you need to do to reset the truck..? Is it just a matter of selecting 1st or second gear or removing the trailer, or do you have to turn it off, and then back on to get it to go again?

I have reset the MFU about 3 times so far thinking it might be that but nothing. 1st and 2nd gears are fine not a problem.

Is your radio 2.4GHz, or crystal type (27MHz, 29Mhz or 40Mhz)??

The radio is a 2.4GHz.

Have you used this radio with the MFC before?

I have never used this radio before at all.

Is it an MFC01 or MFC03?

MFC01, I have always used these ones in my other trucks I had and never had a problem with them.

Also the below photo is a photo of my receiver for my truck and I was wondering whether anybody could tell me whether there needs to be a ariel on it because it doesn't have one and I'm thinking the cab might be breaking connection and that's why it could be shutting down.

[540-MAN]

What truck looks like so far.

[540-MAN]

Originally Posted by mavrick0

Sounds as if you are overheating the ESC and it is going into thermal protection mode and shutting things down. Without the trailer there isn't the load on the ESC so there is no reason for it overheat. Not knowing what trailer you are running I'm going to assume it's probably heavier then the stock Tamiya trailer. One suggestion would be to change the pinion on the motor and drop it down a tooth or two or try going to a crawler motor that has more torque for pulling but not as fast as the stock motor.

This is the trailer I'm running at the moment which it is a normal Tamiya trailer.



I have never had any problems with my last trucks of towing this trailer sometimes it has A-trailer in front of it.

[mavrick0]

When the truck shuts down how long does it take for it to be usable again?

[540-MAN]

Straight away it goes like when the battery is flat shuts down then starts up again.

[mavrick0]

What might be happening is the voltage is dropping below the minimum that the receiver needs and shuts off. This is known as browning out. What causes this is the BEC voltage in the MFU dropping below that minimum that the receiver needs to run. One way to test this, which is kind of tough in our situation, is using an external power source to power the receiver. To do this you would need to use a y-harness since we use all of our slots in the receiver with the MFU and you'd have to disconnect all the red wires coming from the MFU to go into the receiver.

[fhhhstix]

Originally Posted by mavrick0

What might be happening is the voltage is dropping below the minimum that the receiver needs and shuts off. This is known as browning out. What causes this is the BEC voltage in the MFU dropping below that minimum that the receiver needs to run. One way to test this, which is kind of tough in our situation, is using an external power source to power the receiver. To do this you would need to use a y-harness since we use all of our slots in the receiver with the MFU and you'd have to disconnect all the red wires coming from the MFU to go into the receiver.

I believe you are 100% correct. The MFU does not have enough BEC for all 3 servos when the truck is under a load and it shuts down the receiver which shuts the MFU down.

I had this problem with my new CASCADIA build, the MFU worked fine on the bench but in the truck and not even driving the servos pulled more amps than the BEC could provide so the truck just sat there turning on and off. I unpluged the fifth wheel servo, and unhooked the truck would start up and idle until I operated the shift or steering servo. I was using 3 HiTec 645MG servos which were just way too power hungry. I replaced them with standard servos and the truck works fine now. Plus be sure to set the endpoints of the servos to keep them in the operating range of the mechanics it is hooked to.

Travis

[yoyo]

Looking goog. Just love those drive tires. Much more realistic than the tires that come with the kit

[rctrucker2]

540-Man

I really like those aluminum rims you have on your truck. What brand are they and from whom did you order? Are they of good quality? I would like to get a set of aluminum rims for my new Freightliner Cascadia build. I have also seen mention of “Steve’s Rims” in several threads but I have not been able to find a link to them, just the reference. If anyone can direct me, I would also appreciate that information. Thanks for your help.

[Backlash]

OK, the reason for the questions that I asked..

AND Yes, I'm thinking a power problem, but I'm leaning more towards a battery issue than a BEC one.. (However, a battery issue can cause a BEC issue)

Originally Posted by Backlash

Have you got the little limit switch connected up under the 5th wheel?

With the switch connected, the MFU supplies less power to the motor when running without the trailer than it does with it fitted..

Have you got another battery to try?

I was thinking that the problem could be low quality battery packs, and the voltage is dropping below the requirements of the MFU when the using full throttle in a high load situation (like with the trailer attached).. This battery issue COULD also contribute or cause a BEC voltage issue..

What exactly happens when it shuts down in top gear? Do you just lose drive, or do you lose everything (i.e. no steering, drive or gearshift)

Just wanting to get an idea if the MFU is going into a fault mode, (i.e. tripping out) or if it is the receiver/ radio gear..

Does it happen as soon as you select top gear, or can you drive it for a while?

Wanting to know if it could be heat related..

What do you need to do to reset the truck..? Is it just a matter of selecting 1st or second gear or removing the trailer, or do you have to turn it off, and then back on to get it to go again?

Wanting to know what you needed to do to get the truck going again..

Is your radio 2.4GHz, or crystal type (27MHz, 29Mhz or 40Mhz)??

Regarding your concern for no Aerial wire on the receiver.. No aerial is not uncommon in 2.4Ghz systems..

Have you used this radio with the MFC before?

Could the radio be faulty?? Do you have another known working Radio and receiver that you could swap into the truck and see if the problem still occurs??

Is it an MFC01 or MFC03?

Was not sure if the MFC-03 had an inbuilt LiPo cutoff.. I have heard of similar problems occurring with low quality batteries, and high power Brushless motors, and when the ESC has a LiPo cut off turned ON..

No disrespect to the others, but I just cant see how it could be just a BEC issue, when all that you are doing is moving to full throttle in top gear..

HOWEVER, I could see it being a battery issue, where the additional load from the trailer and top gear is causing the battery voltage to momentarily drop below the requirements of the MFU's inbuilt BEC, and thus causing the MFU and radio to "stutter" and stop..

Much of this fault finding is a process of trial and error.. Here are some things that you can try (ONE AT A TIME)..

*If you have another working radio and receiver, try that instead of the Tamiya/Futaba unit..

*If you can borrow another battery off someone to try..

*If your using NiCd or NiMh batteries, and cant borrow another to try, completely discharge one of the batteries that you have, then put it on the charger (fast charge) and then put it in the truck as soon as it finishes charging and try that.. The voltage of a freshly charged battery will be slightly higher than one that has been sitting for a while.. (NOTE. DO NOT do this for LiPo batteries)

*If you think that it could be related to the MFU's BEC, then Disconnect the shift servo (and any other servo's or lights that run off the BEC) and leave ONLY the MFU and steering servo connected.. Manually move the shift servo into 3rd gear, and give it a test run..

*You could try a "stutter stopper" connected to one of the receiver ports, or via a Y lead.. Basically a "Stutter Stopper" is a capacitor that connects in parallel with the BEC.. Capacitors are devices that store a charge, and then can discharge it very quickly into a load.. With the Stutter Stopper connected, it will help to keep the BEC voltage at its correct level.. If you don't have, or cant buy a stutter stopper, you can make one from a 16V 4700 uf (micro Farad) electrolytic Capacitor, and an old servo lead.. Electrolytic Capacitors are polarity conscious, so connect the positive to the RED wire (for Futaba leads) and negative to the Black (for Futaba) and discard (remove/don't use) the white wire..

Mark..

[doodlebug]

Originally Posted by rctrucker2

540-Man

I really like those aluminum rims you have on your truck. What brand are they and from whom did you order? Are they of good quality? I would like to get a set of aluminum rims for my new Freightliner Cascadia build. I have also seen mention of “Steve’s Rims” in several threads but I have not been able to find a link to them, just the reference. If anyone can direct me, I would also appreciate that information. Thanks for your help.

I H builder Steve, in the vendor section.
PLEASE beware of the forum time and post limits, before you can access to the buy and sell section.
Cheers, Neil.

[rctrucker2]

Thanks doodlebug, found it. The wheels look great and are just what I am looking for. Will have to save up some $$ as they are a little more than I was expecting.

[540-MAN]

I couldn't find it.