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Power Limited - Please Schedule Service - Potentially Trailer Mode Related?

ShawnA

Supporting Member
Nov 13, 2017
921
674
Edwardsburg, MI
Hi Brave Ulysses,

I am the OP on the other thread...
Do you have any information or post the invoice of your mobile service encounter???
As I received my car there was no voltage at the 12 volt pin.
There was not even a wire going to the location from the "trailer accessory"
circuit or anywhere else...
The way the mobile tech changed mine - It only has power when the car is "On."
That seems to be the way yours is too...

I have not yet tried to tow with the trailer that has its own battery.
The battery is for breakaway brakes.
I have been using a trailer small enough that it does not require
the breakaway brakes...

Thank You,

Shawn

PS - I found a diode the other night that should work if I need it...
 

Gnat

New Member
Aug 28, 2017
4
2
Bay Area, CA
My Model X has experienced this message (power limited - please schedule service) 2x this weekend while on road trip, losing power while driving on freeway in 96 degree heat (car has tow package but I wasn't towing at the time). My first time with Emergency Roadside Service (after 2 hang ups and over hour wait), they said they couldn't diagnose remotely and I required tow to service center. After tow to Service Center, it was closed and Sales couldn't provide loaner. Warning message went away so I began driving home, only to have warning appear half hour later and lose acceleration on freeway again. Lucky to coast into hotel at offramp and now have to wait until Monday for mobile service. If tow is required again, Tesla will not pay, stating only one tow per warranty issue. Is this a known issue with Model X? Advice? This experience has been a nightmare and making me re-think owning a Tesla.
 

Marcia L

Member
Oct 16, 2018
36
20
Tucson, Arizona
I know this thread is old but I just found out about it because my Tesla service tech printed it out for me. We had this problem recently and it was an awful experience. Because we were in Texas, on a 2+ week trip from Arizona. I have a 2018 MX P100D, bought in March 2018, towing a Bowlus Road Chief Endless Highways. This is a new trailer and we'd only taken one short trip prior to this trip and did not have the Power reduced problem them. This time, we drove approx. 1000 miles, stopping at every Supercharger on our route along I-10 and had no problems. Then, when we were leaving our first camp, I got that Power reduced message. We wasted that entire day trying to resolve it. Tesla couldn't or wouldn't send out a mobile tech but they did tow us to the nearest service: 1-1/2 hours away. But without the trailer, they couldn't reproduce the problem and could find nothing wrong with the car. Best option was to reload the last big Christmas software thinking maybe it was corrupted. We drove back to camp that evening, rehooked up the trailer and drove back to a camp spot and the message was gone, so we thought maybe they fixed it. But...a day later when we started to leave again, there it was. At this point on a Sunday, I had no option other than to drive/limp south to our next destination, where we would stay at an RV park until returning home.

At the RV park, I was able to contact our local Arizona service rep and told him our woes and how on earth were we going to get home? and begged him to help get us a mobile service tech. Which he did (what a Saint!) and several days later, mobile tech met us at our camp and got on the phone with our Arizona rep and the two of them started troubleshooting. They had us hook the car up to someone else's trailer (Luckily just the day before, someone across the way had come over to talk with us about our rig and he was willing) and the Power reduced message came on hooked up to his also. So we ruled out the trailer as the problem. Then he removed a fuse, and the message disappeared! They had us do a test drive, just out the RV park, down the road a mile and back and everything worked fine, including the RF brake controller. What a relief! However....

The morning we were set to return home, all hooked up and ready to go and the RF brake controller would not connect! So I had to drive all the way back with no trailer brakes. Which wasn't as bad as it sounded, with regenerative braking. Tesla service wanted me to bring the car in as soon as possible when we got back, and I just picked the car up yesterday. This is what they think:

To back up, when I first got the trailer, the RF brake controller wouldn't work. @idoco gave me some tips on what could be happening, and Tesla service came out and switch the wires in the 7-pin and then it worked, as did all the lights. However the way the wires were switched, there is the possibility for the trailer battery to send amps back to the car, and that triggers the Power reduced message. Apparently, as others have said, this design was changed sometime in 2017. Why does this happen sometimes but not always? Perhaps depending on the relative charge of the two batteries? Also, tech informed me the 12V "drive" wire in the Model X is 15A and my Prodigy RF brake controlled needs a 20A circuit so regardless, we are in danger of blowing a fuse. HIs best recommendation? Take the car to someplace like The Specialists and have them run a dedicated 30A cable to pigtail into the pin 1 of the 7-pin connector. My expense of course :( For now, they switched the wires back to "stock".
He also said the current set up would work fine with a conventional brake controller but that is not what I have. And the fuse they removed at our camp that 'fixed' the problem was the fuse that allowed communication between car and trailer batteries. Now why the RF brake controller worked after that on our test drive is a mystery.

In addition, 3 times I have had the message come on that disables Traction control, brake control, stability control, cruise control and each time all were restored after the next Supercharger stop. Service thinks this 'may' be related to the other issue but they aren't sure.
 

idoco

Member
May 7, 2013
549
596
Outside Philly
@Marcia L Thanks for the info. Glad things "worked out". Hopefully you'll find a suitable solution.

FWIW we've never had a problem with the Prodigy current draw on the 15A fuse and factory wiring. I realize we have the "older" wiring configuration. My point being that the factory wiring and fuse should have enough capacity for the brake controller circuit.

So I'm wondering if just putting a diode kit on the power wire, to prevent feedback, would be a solution. In other words reconnect the 12v wire with the diode in line. This should prevent the feedback problem. And the current 12V wiring and 15A fuse should be sufficient.

https://www.etrailer.com/p-RM-690.html

Maybe an electrical engineer @ohmman could chime in?
 
Last edited:

doghousePVD

My grandfather’s car
Dec 3, 2018
587
472
New England, USA
A bit worrisome. We about to leave on a 3000+ mile camping trip, our first. Only towed the trailer home, no problem. A few days later had a 12 volt battery problem that was a cluster f to resolve. Eventually Tesla replaced the battery without any clear understanding what happened.
 

ShawnA

Supporting Member
Nov 13, 2017
921
674
Edwardsburg, MI
Hi @doghousePVD,

A few questions:
Do you use the Prodigy RF brake controller?
If not, do you use a Prodigy or another hard wired brake controller?
Does your car provide 12 volts to charge a trailer battery?

Shawn
 

Marcia L

Member
Oct 16, 2018
36
20
Tucson, Arizona
I had another wire run from the battery to pin 1 on the 7-pin like Tesla service recommended. Just picked up the car from the shop this morning but haven't had time to test it. Hopefully that will solve the issue. They think it will.


@Marcia L Thanks for the info. Glad things "worked out". Hopefully you'll find a suitable solution.

FWIW we've never had a problem with the Prodigy current draw on the 15A fuse and factory wiring. I realize we have the "older" wiring configuration. My point being that the factory wiring and fuse should have enough capacity for the brake controller circuit.

So I'm wondering if just putting a diode kit on the power wire, to prevent feedback, would be a solution. In other words reconnect the 12v wire with the diode in line. This should prevent the feedback problem. And the current 12V wiring and 15A fuse should be sufficient.

https://www.etrailer.com/p-RM-690.html

Maybe an electrical engineer @ohmman could chime in?
 
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Reactions: idoco

doghousePVD

My grandfather’s car
Dec 3, 2018
587
472
New England, USA
Hi @doghousePVD,

A few questions:
Do you use the Prodigy RF brake controller?
If not, do you use a Prodigy or another hard wired brake controller?
Does your car provide 12 volts to charge a trailer battery?

Shawn
I use a Tekonsha controller. I removed the circuit breaker in the trailer so the Tesla cannot supply 12 volt any more. I never want to discharge the Tesla to the trailer (except running lights of course.)
 

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