NEMA 14-50 Charging Issue - 5 blinking red lights

NEMA 14-50 Charging Issue - 5 blinking red lights

Hello All,

I am having a very weird charging issue with a newly installed NEMA 14-50 socket. When I plug in the UMC to my 14-50 socket the Gen 2 UMC goes through the boot process, then the "T" in Tesla starts blinking red 5 times, and this will continue whether the car is plugged in or not. When I plug the UMC into the car, the car dash shows that it is pulling 240V, the charge port blinks the regular green, but the amps are restricted to 8A and I get a error message on screen saying check adapter. Going to the UMC manual trouble shooting section (, 5 red blinking lights indicates an adapter fault. That being the case I have my electrician leave as I tell him I probably have a faulty adapter. I then drive down to the Tesla SC and they plug my UMC in with my adapter and everything works perfectly. Drive home and call the electrician who comes back out and checks the line (everything is pulling fine on a 50A breaker, showing 240V as does the car), he even replaces the NEMA 14-50 socket and upon plugging it in, same 5 red blinking lights. At this point I have no idea what the problem is and its driving me crazy. If I plug the UMC into the 120V socket using the 120V adapter, then everything works fine, no red blinking lights, charges perfectly fine. As soon as that 14-50 gets plugged in, the red lights happen. Looking for any suggestion that would help me out since I have basically ruled out the common causes for the adapter failure (SC trip), and socket failure (electrician re-visit and line test).

I also tried jamming the adapter into the UMC as much as it would go, since I know that others have fixed 5 red blinking lights due to the adapter being loose. I even kept pressure on the adapter while it was plugged in and no dice. I have scheduled another service center visit and I will have them provide me a loaner adapter or maybe even a loaner Gen 1 UMC to see if that works.

Thanks all.

donharvey2323 | 2019年4月5日

Make sure the ground is good on the 14-50.

lbowroom | 2019年4月5日

5 red blinks indicates the adapter plug may be sliding our of the charger body. you say you jammed it in hard as far as it would go? Is it not going in all the way? Look different than the 110 adapter?

Zakynthos | 2019年4月5日

I had the 5 blinking lights too and Tesla SC determined the cable was faulty. Replaced it and everything was back to normal. Maybe try a 14-50 at a friends house? If it works there then it should tell you it's not the cable and something is wrong from the wall. Is this a certified, vetted electrician? You really want someone professional for these installs.

jestrada3 | 2019年4月5日

Thank you for the responses guys. The electrician I used is California certified and has done Tesla installs before. He checked the entire socket and it was fine. I am not getting the ground fault error, so I don't think it is the ground that is the issue. As I stated, the UMC was tested at the Tesla SC and it worked there. I did jam the adapter in and it doesn't look any different than the 110 adapter, so I am super confused. There is an RV Park somewhat close that has a 14-50, that I will test out.

crmedved | 2019年4月5日

The UMC is very sophisticated at detecting wiring issues. It isn't like a dryer or something that wouldn't care. My guess is something the electrician did isn't quite right once a load is put on the circuit.

I'm still using 120V for my car. I got the 5 blinking lights and 8A for unplugging the adapter while it was plugged into my car (but not charging). Unplugging it from my car and unplugging it and plugging it back into the wall didn't help. I let it go and checked like 30 minutes later and it went back up to my crappy 12A :) But yeah, time might not help your situation.

mtofigh | 2019年4月7日

I have the same issue. I tested the 14-50 at two differnt outlets at the different homes and same issue: red light blinking 5 times, limiting to 8 amps. Sucks.

rpc_in_va | 2019年4月7日

Sure sounds like a problem with the home wiring. Can you borrow a different UMC to try at home, maybe from the SC? If that doesn’t work any better, might be time to invite another Tesla owner to drop by and plug in. Where are you?

Passion2Fly | 2019年4月7日

I agree with @rpc_in_va. Your home wiring might be a problem.
The 14-50 adapter pulls 240 volts out of two legs of your electrical panel. If the panel is not well balanced, you might have a larger voltage drop on one leg versus the other. The UMC will sense that and show a fault. It’s trying to protect your home...
You mentioned the SC testing your adapter. Did they test it with a 14-50 outlet at the SC or a regular 120 Volta outlet?

jestrada3 | 2019年4月8日

Hey guys,

Just wanted to update my situation. I stopped by the SC again and I straight asked them to swap the adapter for me. The tech I worked with said this was a known issue with some adapters and happily tested and swap the 14-50 adapter for me. Got home and viola, I am charging at the full 32A. So for anyone (@mtofigh) getting the 5 blinking lights error, unless your adapter is not fully plugged into the UMC, get a replacement from Tesla.

PECo CT | 2019年4月9日

Rich of Rich Rebuilds on YouTube has a video in which he fixed that problem, which is with the charger. Earlier versions used a cable retention system that allowed the cable to pull out of the charger, which could pull some of the wires loose from the charger. He showed the new cable retention system, which is much more robust.

Tesla really should issue a recall for this problem. Ask Tesla Service to either repair or replace your charger.

eugv86 | 2019年5月2日

I have the same issue right now.

1) Had Tesla give me a new UMC
2) had my electrician test the outlet for correct voltage
3) car saying it's getting 240 volts but maxing out at 8amps

Not sure where to go from here.

Guybrush | 2019年6月18日

Had the same issue. Electrician came back and replaced the breaker. Still no good. Replaced UMC charging cable, still no good. Then, replaced adapter - finally works and charging at 32amps.

karenrubinclan | 2019年11月8日

I’m now having the same problem with the 14-50. I thought I fixed it by unplugging and replugging into the outlet. But that only temporarily worked. This is frustrating.