Trailer Sway Control?

[RichSNJ]

So I'm hauling a travel trailer with my L for the first time today. All in all there's plenty of power and if it weren't for the issue I'm bringing up, it would be a pretty stress free experience.

However...

I own a Harbor Freight 1700lbs Gross trailer that I purchased / built when I got my 2019 Grand Cherokee, which I believe also had Trailer Sway Control. I never had any issues pulling that trailer with with my '19, and the one time I've pulled it with my L I noticed that it was "jerky" when diving down the road. I've only used it the one time and basically only for short haul home depot stuff, but it was disconcerting. (M.y HF trailer only has a 4-pin connector with no electric brakes)

I am noticing the exact same sensation towing this 16ft travel trailer. I've got plenty of power and everything is totally smooth, but as I'm driving down the road, I can feel semi-constant "jerking". I'm thinking that maybe it's the Trailer Sway Control hitting the brakes in the back even though there is no swaying going on...

Has anybody else towed anything with their L yet, have any "jerking" issues to speak of?

 

[Jake22]

Trailers should be level to improve stability & prevent poor towing characteristics.

 

[RichSNJ]

Trailers should be level to improve stability & prevent poor towing characteristics.

Yeah, I know, that's another issue I'm trying to deal with right now. I rented that trailer and the owner of it was supposed to supply the hitch. I learned that there are two different sets of pin holes on hitch ball holders and Jeeps will only use the shallower of the two. I haven't been able to find out any information on this yet, but to make a long story short, I had to buy a triple ball straight hitch yesterday because that's all I could get locally and that's what I was using here. I'm currently researching a triple ball adjustable drop hitch to use as a backup in the future if this arises, but eventually if I actually buy a trailer I'll get a WDH with anti-sway. This does not alter the "jerkiness" problem I'm having, as I was getting that even on my little 1700 lb trailer that I pull with my regular drop hitch (with a 2 inch trailer ball).

I did however drive 300+ miles with it since yesterday and I've learned to live with it.

 

[eleceng1979]

The electronic TSC works like this…

• The system monitors the vehicle’s movement relative to the driver’s intended path and the vehicle yaw sensor recognizes sway
• System applies brake pressure on one front wheel to counteract the yaw induced by the trailer and applies brake pressure to all four wheels to slow the vehicle
• As the trailer sways to the other side of the vehicle, Trailer Sway Control will increase pressure to the opposite side of the vehicle
• The system will continue to apply alternating brake pressure and reduce engine torque until the trailer is under control

If your jerking is fore/aft, you have a loose receiver/ball figment. My WK2 factory hitch was oversized somewhat and allowed the receiver to move around. It was wrapped in some friction tape to stop the clunking. A good tight hitch pin helps. The trailer that is not level will have almost no tongue weight which will cause the same problem. On WK2, with factory tow and TSC, I had no issues with 5900lbs on a pintle hitch. It did jerk at stopping/starting due to pintle, but never did on a ball hitch. Factory WL tow packages have menus for trailer towing brake setup inside the evic. The factory settings are pretty bad.

 

[RichSNJ]

The electronic TSC works like this…

• The system monitors the vehicle’s movement relative to the driver’s intended path and the vehicle yaw sensor recognizes sway
• System applies brake pressure on one front wheel to counteract the yaw induced by the trailer and applies brake pressure to all four wheels to slow the vehicle
• As the trailer sways to the other side of the vehicle, Trailer Sway Control will increase pressure to the opposite side of the vehicle
• The system will continue to apply alternating brake pressure and reduce engine torque until the trailer is under control

If your jerking is fore/aft, you have a loose receiver/ball figment. My WK2 factory hitch was oversized somewhat and allowed the receiver to move around. It was wrapped in some friction tape to stop the clunking. A good tight hitch pin helps. The trailer that is not level will have almost no tongue weight which will cause the same problem. On WK2, with factory tow and TSC, I had no issues with 5900lbs on a pintle hitch. It did jerk at stopping/starting due to pintle, but never did on a ball hitch. Factory WL tow packages have menus for trailer towing brake setup inside the evic. The factory settings are pretty bad.

Do you know if the system will alert you that TSC is active in anyway? Some kind of dash warning or the like? Yes, it is a fore/aft jerking, so I'm open to all possibilities, but it just doesn't seem likely to me that my little trailer with maybe a few hundred pounds on it was able to jerk me back and forth, plus I had a hitch "tightener" installed on it when I had the small trailer on, and that's when I first noticed it. I didn't have the tightener with me this weekend so I don't know what effect that would have had, but I will certainly investigate this possibility further.

I ordered a fairly substantial tri ball adjustable drop hitch today to use as my backup multi purpose hitch going forward, so when it comes I will certainly see how tight I can get it.

 

[eleceng1979]

When TSC is functioning, the “ESC Activation/Malfunction Indicator Light” will flash, the engine power may be reduced and you may feel the brakes being applied to individual wheels to attempt to stop the trailer from swaying. TSC is disabled when the ESC system is in the “Partial Off” mode.

The hitch tightener stops the receiver rattles, but does not control fore/aft axial movement, just up/down/left/right. The receiver pin controls the bucking. You have a factory or a cheap/undersized pin. Or the ball is loose/wrong shank size. Bucking back/forth is typical on undersized pins/sloppy pin holes in the receiver/hitch. Just because the pin is tight in the hitch doesn’t mean the receiver hole size is not too large. You will have some noticeable bucking when hard braking/acceleration, it cannot be eliminated. It shouldn’t be causing whiplash. With such a small HF trailer, with proper tongue weight, it should be invisible to the driver. Light tongue weight/empty will cause a trailer to dance around and also rattle at the ball and is dangerous to say the least.

 

[RichSNJ]

When TSC is functioning, the “ESC Activation/Malfunction Indicator Light” will flash, the engine power may be reduced and you may feel the brakes being applied to individual wheels to attempt to stop the trailer from swaying. TSC is disabled when the ESC system is in the “Partial Off” mode.

The hitch tightener stops the receiver rattles, but does not control fore/aft axial movement, just up/down/left/right. The receiver pin controls the bucking. You have a factory or a cheap/undersized pin. Or the ball is loose/wrong shank size. Bucking back/forth is typical on undersized pins/sloppy pin holes in the receiver/hitch. Just because the pin is tight in the hitch doesn’t mean the receiver hole size is not too large. You will have some noticeable bucking when hard braking/acceleration, it cannot be eliminated. It shouldn’t be causing whiplash. With such a small HF trailer, with proper tongue weight, it should be invisible to the driver. Light tongue weight/empty will cause a trailer to dance around and also rattle at the ball and is dangerous to say the least.

Well you've given me some things to consider, I'll have to play around with the HF trailer once I get the new drop hitch. The new hitch has a system with rubber gaskets that go around the shank and a metal plate that you tighten down towards the receiver so that it's actually applying a constant force against the pin. Do you think that system would mitigate what you're describing?

 

[eleceng1979]

The new hitch seems like it would help. Keeping it loaded against the pin will solve many problems, but will loosen somewhat if the pin holes are sloppy/pin too small. The pin takes all accel/decel load. 10% tongue weight up to around 400lbs (can’t remember max tongue weight), a level trailer to hitch, good weight distribution to keep weight at tongue in check, with properly sized hitch balls is textbook. An empty trailer no matter it’s size rides rough and has little tongue weight until you get into 15’+ length. The HF trailer is probably a tilting model, these empty, at highway+ speeds will act like an airplane wing and constantly rattle up/down.

 

[RichSNJ]

Well hopefully this will address the issue. I ordered one hitch on the advice of an RV forum, but I returned it because it had a lot of wiggle and it had a solid shank, so I couldn't use the pin lock that I've got now. The new B&W hitch is fully adjustable, but I'm using a locking hitch pin which puts a 2 inch block of steel into the hollow shank of the hitch and the pin actually bolts into it allowing me to tighten the hitch into the receiver so that it's rock solid... Should prevent any side to side or front back motion. I plan on towing my utility trailer this weekend, but won't know about a big trailer till probably June...



I was really concerned about the drop length since it's not a truck, but even with it at it's lowest position, there's still a foot of clearance between the lowest point and the ground...

 

[Dave180]

So I'm hauling a travel trailer with my L for the first time today. All in all there's plenty of power and if it weren't for the issue I'm bringing up, it would be a pretty stress free experience.

However...

I own a Harbor Freight 1700lbs Gross trailer that I purchased / built when I got my 2019 Grand Cherokee, which I believe also had Trailer Sway Control. I never had any issues pulling that trailer with with my '19, and the one time I've pulled it with my L I noticed that it was "jerky" when diving down the road. I've only used it the one time and basically only for short haul home depot stuff, but it was disconcerting. (M.y HF trailer only has a 4-pin connector with no electric brakes)

I am noticing the exact same sensation towing this 16ft travel trailer. I've got plenty of power and everything is totally smooth, but as I'm driving down the road, I can feel semi-constant "jerking". I'm thinking that maybe it's the Trailer Sway Control hitting the brakes in the back even though there is no swaying going on...

Has anybody else towed anything with their L yet, have any "jerking" issues to speak of?


View attachment 4005

The trailer will jerk fore/aft if you have the smaller sized 1/2" pin installed. It must be 5/8". Also, that travel trailer is tilted upward and it should be towed level. Trailer axles have a small degree of toe in and caster built in to them for managable towing when flat/level. If you raise the front end you are creating an odd degree of caster/toe which will cause the trailer to wander left and right.

 

[RichSNJ]

The trailer will jerk fore/aft if you have the smaller sized 1/2" pin installed. It must be 5/8". Also, that travel trailer is tilted upward and it should be towed level. Trailer axles have a small degree of toe in and caster built in to them for managable towing when flat/level. If you raise the front end you are creating an odd degree of caster/toe which will cause the trailer to wander left and right.

I don't know what's causing the issue I'm describing, but I've just decided to live with it. I get the issue towing my little Harbor Freight trailer with about 1,000 pounds on it, and I never got it with the exact same load on my '19 GC. I have a new adjustable drop hitch, use a bolt in hitch pin which is very very secure, and I also use a hitch tightener. The hitch is not moving back and forth or up and down. I can't explain it but it just feels like the Jeep itself is surging. Don't know, probably will never know.

 

[eleceng1979]

have you by chance checked the tires on the trailer? Bias ply? Or unbalanced? It just could be bouncing due to its small size/weight/tires. Go borrow/rent a large 2 axle trailer for a around the block test to prove that. I hope your bolt is a purpose built hitch bolt, not a grade 0 Lowe’s special lol.

 

[RichSNJ]

have you by chance checked the tires on the trailer? Bias ply? Or unbalanced? It just could be bouncing due to its small size/weight/tires. Go borrow/rent a large 2 axle trailer for a around the block test to prove that. I hope your bolt is a purpose built hitch bolt, not a grade 0 Lowe’s special lol.

The exact same sensation I feel with the little Harbor Freight trailer is what I felt with the Travel trailer.

Yes, it is a 5/8" hitch pin designed for the purpose.

 

[eleceng1979]

Then probably some sort of engine/trans surge. Try pulling trans into manual and dropping a gear or two while flat to see if surge goes away. High load/low rpm is always surge territory on the motor. If going from manual -1/2 gears and D causes it to go away and return, you know your answer. Cheap, lower octane fuel will cause a vicious engine control loop to pull ignition timing when knock is detected and then add it back in, then detect knock again. This loop can cause such a sensation under high loads. Don’t know your engine but minimum octane ratings vs best performance is stated for a reason. Engine fuel programming can also be jacked to cause surge also, but is a factory issue. I suspect it might be related to your fuel as both engine programs are mature. Plenty of such issues have already been worked out and in use for years. To get max fuel economy they advance timing as much as possible and they will run on min octanes with very little margin for knock and will knock under certain situations.

I think back on earlier WK2 there were TSB’s related to V6 platforms for this. V8 always had issues with low freq vibrations due to MDS in driveline also. I always manually shifted when towing. But don’t know about WL.

 

[Jake22]

I think back on earlier WK2 there were TSB’s related to V6 platforms for this. V8 always had issues with low freq vibrations due to MDS in driveline also. I always manually shifted when towing. I don’t know about WL.

🥱

 

[RichSNJ]

Then probably some sort of engine/trans surge. Try pulling trans into manual and dropping a gear or two while flat to see if surge goes away. High load/low rpm is always surge territory on the motor. If going from manual -1/2 gears and D causes it to go away and return, you know your answer. Cheap, lower octane fuel will cause a vicious engine control loop to pull ignition timing when knock is detected and then add it back in, then detect knock again. This loop can cause such a sensation under high loads. Don’t know your engine but minimum octane ratings vs best performance is stated for a reason. Engine fuel programming can also be jacked to cause surge also, but is a factory issue. I suspect it might be related to your fuel as both engine programs are mature. Plenty of such issues have already been worked out and in use for years. To get max fuel economy they advance timing as much as possible and they will run on min octanes with very little margin for knock and will knock under certain situations.

I think back on earlier WK2 there were TSB’s related to V6 platforms for this. V8 always had issues with low freq vibrations due to MDS in driveline also. I always manually shifted when towing. But don’t know about WL.

Engine/trans surge actually is a good description of the issue. I'll try manual shifting. I have the V8 and I always use 87. I'll try 89 when I rent the travel trailer on my trip in June and see what happens.

 

[eleceng1979]

FYI, newer 22+ ram 5.7’s have had problems with torque converter control signals causing a 100-200 rpm flutter while under load, which causes such a sensation. There was a TSB on the ram side for this. Also changing trans fluid to something better has helped a few. I would check with your dealer about TSB’s related to trans torque converter flutter/signal/fluid change issues.

 

[RichSNJ]

FYI, newer 22+ ram 5.7’s have had problems with torque converter control signals causing a 100-200 rpm flutter while under load, which causes such a sensation. There was a TSB on the ram side for this. Also changing trans fluid to something better has helped a few. I would check with your dealer about TSB’s related to trans torque converter flutter/signal/fluid change issues.

Do you know if it is only when towing? Everything is completely ok when not towing.

 

[Jake22]

https://shockerhitch.com/product/shocker-xrc-cushion-hitch-build-your-own/

 

[RichSNJ]

https://shockerhitch.com/product/shocker-xrc-cushion-hitch-build-your-own/

View attachment 4041

That's pretty close to the first adjustable hitch I got, I returned it because the "rubber" bump stops made it really loosey goosey... The B&W is pretty solid.