PCS Problems When Towing

Good evening all,


I am a new member to the forum and Tacoma ownership. I have owned several other pickups and towed many travel trailers over the years. We bought our White 2020 SR 4X about 6 months ago with the intent of hauling a small travel trailer for weekend camping trips. We then purchased our 3200 lb travel trailer and set it up with an Equalizer WDH and a Tekonsha Primus brake controller. The truck pulls very well and is adjusted such that the fender heights before and after trailer and WDH hookup are almost the same within 1/8” or so. No sag, no problems. Returning from our first trip, the PCS system and the Stability Control systems errored out and gave us the malfunction “See Your Dealership” message. The next week I took it to the dealership and got quizzed on any modifications that I had done before they reluctantly reset the system. For the record, I did put some Method wheels with Wrangler 265/70/16 tires which are about 1/10 of an inch taller than stock. Nothing else has been done. I have since pulled the trailer 2 mor times and each time the PCS systems have errored randomly during the trip. The second time the dealership reset the system at my 5000 mile oil change.

Doing a little research on the web I found this link: https://www.toyota.com/content/ebrochure/CFA_TSS_precautions.pdf to a Toyota precaution document that details all of the shortcomings of their Toyota Safety Sense (TSS) systems. This document asks you to turn off the PCS system for many different reasons including towing, or even going off road. Read thru this and you get the “Sense“ that the system is worthless except for driving straight ahead on level roads in the sunshine in a completely bug free environment. Who would build something like this??

I took this document to the dealer and spoke to my Service Rep (SR). He asked me to bring my truck in to be reset the 3rd time and but this time was asked to bring the trailer to the dealership without the brake controller or trailer plugged in so that they could look at it and attempt to replicate the error message. I made my appointment and prepared to head to dealership the next morning with the PCS turned off and the trailer and brake controller unplugged. I made it halfway to the dealership when the error message appeared again even with the PCS off and the trailer unplugged. The Toyota mechanic kept the truck and trailer for the day and tried to duplicate the error but were not able to do so. When I came to pick it up that afternoon, my SR offered to go on a drive with me to see if we could make It happen. PCS off and unplugged, we left the dealership and drove for several miles. We stopped briefly and plugged the trailer in and drove on. After a few more miles we stopped again, and I plugged in the brake controller always being sure the PCS remained off. NO FAULTS OR ERRORS. I drop the SR off at work and continued home. Not more than 5 minutes after dropping the SR off……It errors again as I am driving home. I notified my SR and asked what the next steps for resolution would be. He said that he is unable to do anything until they can see it happen. He suggested that I leave my truck and trailer with them long enough for them to drive and witness the error. The SR mentioned that it might be some problem with my Trailer wiring?? All the trailer wiring appears to be in good shape and all lighting works beautifully so I don’t know where to start with that?

I was hoping to hear from anyone who has had a similar experience with Toyota related to the PCS system and get any advice on where I should go next to either look for the problem or seek relief from Toyota. Let me know what you think. Thanks

 

If it were me, I would plug in my ThinkDriver OBD2 reader and have it scan the system and tell you what’s wrong and where the problem is.

 

Get a '16 with 6MT and you will not have to deal with all those nanny systems

 

Most of the CFA-TSS_precautions are CYA (cover your a$$) statements (for Toyota) just in case things do not work as designed. This is why I did NOT want the Technology Package on my new '21 Taco. Too many of the features offer an excuse to not develop good driving skills. Our '16 Camry has many of the TSS features - most of which have been shut off because they're annoying.
Sorry, but I'm 'old school' when it comes to driving.
I've come to dislike most technological advancements. I do utilize GPS on certain occasions but I still know how to read a map and, over the years, have developed a fully functional sense of direction.

 

EVERY vehicle has limitations on their safety systems not just Toyota so don't blame them. There are simply too many variables man. I don't know what your specific problem is but my guess is some type of intermittent voltage or ground from the trailer is causing it. These systems are extremely sensitive to current as are all modern vehicles.
As far as your dealer fixing it? They can't fix what they can't see.
Good luck man.

 

I know this doesnt help you but I tow my boat a lot. When I drop the boat on the hitch, it lowers the back of my truck by an inch or so. I have never turned off the PCS or done anything different while towing, (except using ECT and S4 or S5 on the flats) and have never gotten a malfunction. My boat uses the flat 5 connector with the trailer brake hook up (it also has surge brakes) and a 7 to 5 adapter. No problems, ever.

 

The latest update on the PCS and Traction control systems erroring out while towing. I had the systems reset at the dealer again and then towed again on the following weekend. This time I removed the Brake controller from the vehicle and only plugged the trailer in to the truck for brake and marker lights. I used my Equalizer hitch with the bars set to a fairly high tension moving a substantial load to the front wheels thru the frame of the truck. While loaded, the rear wheels only showed 1/2" sag and the fronts were the same measurement as when the truck was unloaded, this with about a 400 lb trailer weight on the truck hitch. After starting the vehicle and before moving, I swithced off both the PCS and the Traction Control system. We then towed the trailer about 40 miles both city and freeway driving to about 1 mile from the campsite when the error lights for both systems again light up the dash. The only thing that was interesting was that the road was slightly hilly so the system may have triggered as we rose and descended from one of these bumps leading me to think that the Equalizer hitch may be set with too much tension transferring too much weight to the front wheels. Could it be possible that the rear wheels are getting light over the bump and this is what could trigger the PCS and the TCS?? I attempted to pull the trailer before our trip for a short distance home without the trailer plugged in to the truck but no error code occurred so I am not sure that I can rule out trailer wiring but everything back there is working great. In all cases mentioned in this post, the trailer was being pulled with the safety system turned off so it is really baffling to me now why this occurred at all. I intend to go back to the dealer for another reset and adjust the trailer equalizer hitch bar tension down to put more weight on the rear wheels of the truck and try it all again. I will continue to update this thread as I work thru the problem. Please hit me with any other ideas you all may have. Thanks to all

 

I would think if your rear tires were light you would be getting traction control alerts.

To recap it only happens when pulling the trailer, specifically only when the trailer is plugged in(with or without the brake controller). Never seen that error any other time?

Does the trailer have LED brake/running lights? There is a known issue(not TSS) with the tundras when towing trailers with LED lights.

Did somwone install the brake controller wiring and/or the trailer plugs?

 

It has happened several times now and only when towing with the equilizer hitch in use and the trailer plugged in. I am trying to reduce the variables and have now come to this. The truck only has 6000 miles and had a factory wiring harness that I connected to with a premade Toyota- Tekonsha Primus harness. I dont believe the trailer lights are LED but I can check that. I each case the trailer lights were off as it was daylight. Only brake / turn signals were operational. The TSS system errors randomly going down the road with no brakes, signals or marker lights on and with both the PCS and Traction control systems turned off. I did tow the trailer first without the equilizer hitch from the point of purchase to the storage and then later with the equilizer hitch set up with 4 washers rather than the 5 I have used recently. It did not error out in those conditions. This is either coincidence or maybe not. The whole thing has been very random. This last time however, 5 washers, plugged in, No brake controller and all TSS systems off. Very strange????

 

Another update to the PCS/VSC Error problem. After another system reset at the dealer, I was asked to take the truck and trailer for a test drive without the trailer wiring hooked up to the truck to prove that the trailer electrical has no play in the problem. With both the PCS and VSC systems turned off and the trailer not plugged in. I made it five miles before another error message for both systems. I sent this info to the dealer and they will be forwarding to Toyota for their review See attached for the full history

 

Not that this really helps you but I have the same problem. 2019 everything fine but when I tow my travel trailer it errors for PCS and VSC. I've tried towing with and without PCS turned on, makes no difference. Does it every time I tow the trailer. Never around town but as soon as I hit freeway speeds. About the time I hit 55mph. Trailer is well within specs, weight distribution hitch set up well. Not perfect level but within 1/4". Dealer has no solution other than to reset codes. I just ignore it at this point and reset when I get home. Main irritation is the light show of errors on the dash while driving, can't see the digital speed display etc. Usually it will give me an error on the cruise control also at some point.

 

Thanks for your reply. You are the first and only other that I have communicated with that share this problem. I will be working with the dealership over the next weeks to figure it out. If you dont mind, can you share either here or over PM what model truck you have and the location and name of the dealer you are working through. I have a base model SR with 4X and tow package with only 7200 miles purchased in early May of 2020. I am working with Big 2 Toyota in Chandler Az. So far they have been good to work with but now we will see what they are willing to do to fix it now that I have proven it is not the trailer electricals causing the issue. I will continue to update the forum post as things progress. I will be calling them today to discuss next steps. If you haven't looked at the attachment with the history of failures, please do and let me know if yours are similar. Mine too appear going down the road at highway speed. Thanks for the response maybe together we can get something done??

 

Perhaps there is some information in the towing bible that may assist you with this issue .
There are some great posts within that thread .
If anything , your issue should be added to it to make others aware .
https://www.tacomaworld.com/threads/the-tacoma-towing-bible.4031/

 

I'm impressed by your level of detail on the history!
Mine is a 2019 Doublecab, V6/AT, TRD off-road. about 20k miles. Has pretty much all the options I know of.
Tekonsha brake controller.
Was originally towing a smaller trailer without issue.
Traded up to a larger but still relatively small travel trailer and added weight distribution at that time.
Small Winnebago, 3,400 dry and really don't take much beyond that so not overloaded.
From that point forward, any time I tow on highway it puts up PCS and VSC errors.
I took it in the first time to Tempe Toyota, they saw nothing wrong and cleared the errors. From that point forward I just started clearing the errors myself after every trip. So I have not really been working with anyone about it. Really just seems like the added weight messes with the system. It's not right but I guess I have been desensitized to it at this point. If you get anywhere with it let me know.
I did also search a bit when this originally happened and found nothing that matched. So it would seem its something rare about yours and mine.

 

Interesting stuff. My trailer is also at 3400 lbs dry and I use an Equal-i-zer hitch and use a Tekonsha controller as well. You mentioned that you are able to clear the codes yourself?? I have an OBDII and I use the Torque Pro app but do not get any codes showing when I scan. The SR at the dealer attached his scanner and also got nothing. I have also tried clearing the system by disconnecting the battery for a while and still am unable to clear the errors. For me every time it has happened it has been back to the dealer to clear. What are you doing to clear the codes?? I wonder if the made changes between the 2019 and 2020 that prevent me from clearing the codes?? Any thoughts?

 

Have you tried taking the WDH off and then towing it?

 

I just use a cheap reader off Amazon, plug it in and clear. Taking it out again in two weeks, I'll let you know what the actual codes are then.

No, have not tried towing without the WDH, its got so much squat without it seemed like a bad idea.
But I guess it would be something to eliminate.

 

x2 try it without the weight distribution hitch.

 

My boat and trailer weight about that when fully loaded for duck season. I recently added sumosprings but it towed fine before that. No PCS issues.

 

I have towed a few miles without a WD hitch without a problem when I first bought my trailer and dragged it home. I have not done that though since I installed the hitch.

I would like to now the brand of reader and app name you are using if your reader is a bluetooth type. Also the code next time it happens to you. That would be helpful. I will try to find out from Toyota if things were changed from 2019 to 2020. I will post when I find out. Thanks to all