Turn Signal Fault

[jorobsand]

For the past couple of weeks, I have been getting a Turn Signal Fault indication on my dash of my Model S. Couple strange things to note about the fault:

• I can find nothing wrong with any of the lights themselves. All appear to be operating correcting.
• I receive the fault exactly twice each time I drive the car. Once the first time I use the left turn signal, the second time using the right.
• The fault itself only appears for a second or so, and then disappears. The fault will not reappear for the remainder of the drive.

Tesla service tried to diagnose remotely but couldn't seem to determine the issue. The set up a mobile ranger appointment with the assumption that I had a light out, but when I told them all the lights are working, they were confused and set up a service center appointment. I have that upcoming on Wednesday but was hoping maybe someone in the community has seen something like this before and may be able to help me help guide the service center before they go poking around and tinkering with things that are working fine.

 

[Azathoth]

I had a somewhat similar issue with the right turn signal and headlight. They were intermittent for a few days then stopped working altogether. Mobile service tried replacing the headlight assembly and when that didn't work, asked me to schedule a SC appointment. Turned out to be a "corroded ground connector" (on a 1 month old MS Raven).

Now if they could only fix the 'AUTO' headlights always on in daylight issue...

 

[Dithermaster]

I didn't have a fault but sometimes my right turn signal would not indicate on the dash, but would blink 2x faster on the outside. June 2019 car. All lamps worked. Mobile service disconnected each connection, checked the "pin drag" and re-assembled them. After that, they worked perfectly. He did say one connector (rear one) felt loose when he disconnected it, so we think it wasn't plugged all the way in. Enough that the lamp worked, but sometimes the current detected wasn't correct.

 

[jorobsand]

I didn't start having the problem until after my MCU/AP upgrade. I wonder if they knocked something loose.

 

[jorobsand]

Just an update on this thread - not because the thread itself was extremely popular, but you never know who might come searching for this thread in the future...

When I first took my car in, they were unable to replicate the problem (was the first day I never got the error) and so they were hesitant to start poking around unnecessarily - which I was perfectly OK with. Sure enough, the problem came back a couple days later.

I scheduled another appointment to bring the car back in and was told that the Tesla engineers were looking at the errors and logs and determined that my Front Body Controller was likely going bad and would need to be replaced. Brought the car in, had the FBC replaced and the problem went away....for about a week.

Now the fault error is back again, doing the same thing it was doing before. Going to bring the car in for a 3rd time later this week to see what is next. The service ticket didn't have any idea what they would try/check next as they appear to be perplexed by the problem.

 

[buzescu]

I had same issue recently. Maybe before last update...2 weeks ago. Came in notifying me on 3 trips about 2 times each the vanished. Nothing since.

 

[jorobsand]

I had same issue recently. Maybe before last update...2 weeks ago. Came in notifying me on 3 trips about 2 times each the vanished. Nothing since.

Do you recall which FW version you were on? I had previously ruled out a software bug since I have not yet seen anyone else (besides you) who experienced the same problem.

 

[buzescu]

Do you recall which FW version you were on? I had previously ruled out a software bug since I have not yet seen anyone else (besides you) who experienced the same problem.

I am on 20.16.2.1. and trying to recall I think it was on this over. I don't remember a sw update and it is weird cause that problem just vanished.

 

[jorobsand]

The saga continues...

Brought the car in for the 3rd time and this time they replaced the left front headlamp. Said that since the left and right signal were on the same circuit and they think the headlamp was the problem, this should fix the fault I was getting on both. Any takers on what happened next?

Few days later, the fault is back. Replaced FBC and left headlamp did nothing to resolve. Now scheduled for my 4th visit to the SC for this issue. Really starting to get frustrated.

 

[quickstrike12]

Oh man. That sounds like a pain in the arse. anyway at all to force a firmware update? Even to the same version by the SC? Certainly would not hurt the issue and isn’t invasive.
My next choice would be loose ground somewhere.
out of curiosity have you tried to see if it’s different if you “click “ the turn signal completely as opposed to just the momentary tap to initiate it?

 

[buzescu]

The saga continues...

Brought the car in for the 3rd time and this time they replaced the left front headlamp. Said that since the left and right signal were on the same circuit and they think the headlamp was the problem, this should fix the fault I was getting on both. Any takers on what happened next?

Few days later, the fault is back. Replaced FBC and left headlamp did nothing to resolve. Now scheduled for my 4th visit to the SC for this issue. Really starting to get frustrated.

So my fault is back. I had mobile service replace my left headlamp. He told me these are new posts and I checked my right side is the same, built after Jan 2020. I told him I had this weird encounter but never happened before. He did all the checks. So after this replacement I got the left turn signal fault back few times and now it is back again. I wonder if it is related to new headlamp revision now... In any case my first concern is to see the DRLs not going bad again.

 

[buzescu]

So my fault is back. I had mobile service replace my left headlamp. He told me these are new posts and I checked my right side is the same, built after Jan 2020. I told him I had this weird encounter but never happened before. He did all the checks. So after this replacement I got the left turn signal fault back few times and now it is back again. I wonder if it is related to new headlamp revision now... In any case my first concern is to see the DRLs not going bad again.

Sorry, I meant not "new posts" bit new headlamps, new parts.

 

[jorobsand]

Oh man. That sounds like a pain in the arse. anyway at all to force a firmware update? Even to the same version by the SC? Certainly would not hurt the issue and isn’t invasive.
My next choice would be loose ground somewhere.
out of curiosity have you tried to see if it’s different if you “click “ the turn signal completely as opposed to just the momentary tap to initiate it?

They have been doing firmware updates when I bring it in as part of the diagnostic. And I got updated to 2020.20.5 last night and still received the fault on a drive this morning.

 

[aerodyne]

Just an update on this thread - not because the thread itself was extremely popular, but you never know who might come searching for this thread in the future...

When I first took my car in, they were unable to replicate the problem (was the first day I never got the error) and so they were hesitant to start poking around unnecessarily - which I was perfectly OK with. Sure enough, the problem came back a couple days later.

I scheduled another appointment to bring the car back in and was told that the Tesla engineers were looking at the errors and logs and determined that my Front Body Controller was likely going bad and would need to be replaced. Brought the car in, had the FBC replaced and the problem went away....for about a week.

Now the fault error is back again, doing the same thing it was doing before. Going to bring the car in for a 3rd time later this week to see what is next. The service ticket didn't have any idea what they would try/check next as they appear to be perplexed by the problem.

Did they ever look at or replace the turn signal module/stalk? I had a similar problem, the whole assy was replaced, and it fixed it.

 

[jorobsand]

Did they ever look at or replace the turn signal module/stalk? I had a similar problem, the whole assy was replaced, and it fixed it.

Can't say - but I will definitely bring this up when I bring the car back to the SC this week. Thanks!

 

[aerodyne]

Can't say - but I will definitely bring this up when I bring the car back to the SC this week. Thanks!

They told me this was a known issue for MS in the '14-16 year range, but I do not see any SB for it.

Problem fixed a year ago, has not recurred.

 

[jorobsand]

They told me this was a known issue for MS in the '14-16 year range, but I do not see any SB for it.

Problem fixed a year ago, has not recurred.

I have a late 2017 (December) Model S.

 

[aerodyne]

I have a late 2017 (December) Model S.

Not exactly sure of the date range, might be '17 as well?

 

[jorobsand]

The SC just called me and told me it was because I was using a dashcam that tapped off the windshield break sensor in the microphone grille and that I would have to pay for a fix (even though under warranty).

I told them that doesn't make any sense because I have had the dashcam for years and the issue only cropped up a month ago. AND that I was like many others who install a dashcam that way and I haven't seen anyone else with the issue. They said that the sensor uses the same electrical circuit as the turn signals and that was their conclusion for the problem based on recent firmware updates that may cause it to do this. I said I would have expected others to have seen the same problem if that was the case.

Anyway, I am taking the car back home today and plan to do my own testing with video. I am hoping I can prove that the problem does appear with the dashcam unplugged (which they said it doesn't) and then may have to bring it a back a 5th time to compel them to fix under warranty.

 

[aerodyne]

The SC just called me and told me it was because I was using a dashcam that tapped off the windshield break sensor in the microphone grille and that I would have to pay for a fix (even though under warranty).

They told me a similar story, that my CAN bus reader broke the car. It was removed, and they insisted that the car was fine. Upon my contactless "delivery". Car was completely dead in the SeC driveway.

Turned out it was contactors in the main pack.

Push back on this..at least one SeC told me the turn stalk issue is a common problem..

I told them that doesn't make any sense because I have had the dashcam for years and the issue only cropped up a month ago. AND that I was like many others who install a dashcam that way and I haven't seen anyone else with the issue. They said that the sensor uses the same electrical circuit as the turn signals and that was their conclusion for the problem based on recent firmware updates that may cause it to do this. I said I would have expected others to have seen the same problem if that was the case.

Anyway, I am taking the car back home today and plan to do my own testing with video. I am hoping I can prove that the problem does appear with the dashcam unplugged (which they said it doesn't) and then may have to bring it a back a 5th time to compel them to fix under warranty.