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What exactly is the 1146 Alert?

gregd

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Dec 31, 2014
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Probably best answered by Mr. Gruber, but I'll send this out to the collective group.

What exactly is the car complaining about when it coughs up a "1146 DMC Motor Fan Problem" alert?

I just had the car put through the annual service at the local SC. Very stressful for both me and the car, but that's another issue. I finally have the car back, and now it's reporting 1146 errors at various times. Several during charging (including some that occurred immediately before or after the charging session, and some in the middle), and some while driving (e.g. just after I punched it to pass someone on the freeway today, but also one where I was simply parking the car in the garage). PEM and motor temps seemed about average, I suppose, given the ambient conditions.

Part of this annual service focused on the PEM Fan connector, and making sure that it was properly dealt with. Contacts cleaned with DeOxit, but the tech who did the spraying got it all over the rubber part, and ruined the connector. New connector installed (unknown if the same pins were re-used or not). Alerts have continued after that. Oddly, the alerts were not happening when I unknowingly drove the car with the ductwork not fully attached to the bottom of the PEM, and the PEM was running very hot as a result (power limited). That was part of the stressful part of the annual "service".

I note that I'm not getting 1144 alerts (PEM fan problem, as opposed to Motor fan problem). The car does have the upgraded blower config, so there is in fact only a single motor that covers both. I had this problem several years ago, and was told that there is no actual RPM indication (no tach) on the motor, but the PEM deduces the problem from a combination of current drawn and temperature changes expected. I'm also under the impression that the blower motor is actually a 24v unit, so is driven by putting the two original 12v fan power leads in series, though the electrical engineer in me is questioning that over grounding issues. If in series, the current in one must be identical to the other.

The final thing done years ago that seemed to fix the problem was putting some weather stripping somewhere in the ductwork. I talked to the tech about this, and he tried to put some between the duct housing and the underside of the PEM when they fixed that little oversight, but couldn't and said it was just too tight there. He also confirmed that there was no evidence that there ever was any in that location. Perhaps, he offered, that it was at bottom where the blowers attach? He said that area can be leaky as well.

So, I don't know what they actually do with the ductwork, blowers, et al, during a service. How much is taken apart, beyond the plastic housing that attaches to the underside of the PEM? Is it possible / likely that this is simply that whatever weatherstripping that was put in place years ago was either removed or fell out? Or is this an indication that the issue is still that electrical connector under the PEM?

The tech is out today, but I'll try to get in touch with him as soon as he gets back. He is an experienced Roadster tech (started in the Bay Area), but any help from the collective mind here would be appreciated.
 
The fan is 12V. I find it curious that so many owners have reported the 1144/1146 errors after a service. Based on my own experience, I think the error occurs when the impedance of the circuit is not what the PEM expects. In my case and many others that meant a compromised electrical connection, not a mechanical problem. YMMV.
 

gregd

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Dec 31, 2014
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The fan is 12V. I find it curious that so many owners have reported the 1144/1146 errors after a service. Based on my own experience, I think the error occurs when the impedance of the circuit is not what the PEM expects. In my case and many others that meant a compromised electrical connection, not a mechanical problem. YMMV.
Ok, thanks. 12v makes a lot more sense. So, the PEM is managing the drive to the fan, and doesn't see the right corresponding current draw. If that's the case, then it means that one or more of the pins is already not doing what it needs to do, and is probably already damaged. Thaaaat's not good.

Hmmm... When this happened the first time, I was getting a mix of 1144 and 1146 errors. This time it's just 1146. I'm guessing that is significant, perhaps indicating the specific pin or pins that are failing? Anybody know which pin is which (motor vs PEM fan before the upgrade)?

Also, there must be a connector on the other end of the cable from the PEM, but I've never heard of that one failing. I'm guessing it is not removed typically during an annual maintenance procedure.
 
It’s a hassle getting to the connector. Just replace the whole works while you’re there and sleep knowing you did what you could. The parts are literally like $10. The end at the fan only gets disconnected if you’re pulling the fan which doesn’t happen in a typical annual service.
 
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gregd

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Dec 31, 2014
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According to the wiki, 1144 is PEM fan and 1146 is motor fan. The codes don’t reflect the upgrade to the single motor fan.
Right, but I was getting a variety of both a few years ago, and this time just the one. So I'm thinking that both contacts were going bad back then, and this time only the ones related to the original motor fan. It could be helpful for the tech to know which contacts those are.
 

gregd

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Dec 31, 2014
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It’s a hassle getting to the connector. Just replace the whole works while you’re there and sleep knowing you did what you could. The parts are literally like $10. The end at the fan only gets disconnected if you’re pulling the fan which doesn’t happen in a typical annual service.
Thanks, that helps eliminate both the connector and removal of any weatherstripping that might have been installed there.
 

Logticom

2010 Roadster Sport | 2015 Model S 85D
Supporting Member
Jul 19, 2018
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Zwolle The Netherlands
Hereby my experience of #1146 alerts...
I have had a lot of #1146 alerts like I mentioned here:

#1146 DMC Motor Fan Problem?

The alerts started showing up a couple of months after doing a PEM clean.
I also sprayed "contact spray" on the connectors that messud up my connectors.
You can see a picture of the orange rubber in the connector that I took out to put the connector back on in this post:

DIY: Roadster 2.5 PEM cleaning - step by step

I think the cause of my #1146 alerts were the connectors (without the orange rubber) or the water / moisture that was on my PEM fan.

After taking the PEM fan of and drying it with blowing air on it, I got the alert less frequent.
Then a couple of weeks later I replaced the PEM fan connector with a new one (including the rubber) and I only got a few more alerts in the next week. (replacing is possible without removing the PEM)

Just last weekend I took the PEM off and I also replaced the connector of the "6 pin connector" and also cleaned the 4 pin connector.
And I haven't seen the #1146 since then.

So I also think (like @PV-EV said) it is more an electrical thing than a mechanical thing.
 

gregd

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Dec 31, 2014
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Right, the 4-pin connector (the one at the end of the PEM) is the one that drives the fans. Presume it's a pair of voltage and ground, one for each of the original motors, and wired in parallel (plus to plus, ground to ground) for the upgrade.

But which is tagged for PEM, and which for Motor?
 
The six pin connector is the ESS heater. It looks like on the four pin connector pins one and three are for the original motor fan. #1 being +12v. Really makes no difference which is which as they are paralleled like you said. It would make absolutely no sense to replace only one pin. To do a thorough job you need to replace the whole works including the right angle connector in the PEM. The PEM has the male pin, the free hanging connector is the female.
 

Roadster

JdeMO Powered
Dec 10, 2016
1,674
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SoCal
I've had to contend with #1146 twice now on my 2.5 Sport and both times the fix was a full replacement of the dual motor fan unit itself. According to Javier with @ExecMotorwerkz those units are notorious for being problematic. The good news is they're readily available from SPAL and the swap isn't too difficult. He suspects it may be the brushes and is looking for a way to potentially refurbish the unit by replacing them. So make sure to hang onto your cores if you have them swapped out like I did.
 

gregd

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Dec 31, 2014
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If they didn't touch the blower motor during the service, then it would be an amazing coincidence that the 1146's started right after I got the car back. So, I'm not thinking it's the motor itself.

The only thing that's puzzling is that right after I got the car back, it was driven a bit with what I later discovered was the ducting not quite attached to the underside of the PEM. So the PEM was running really hot (yellow zone, and power limited). I wonder if that did some damage? The errors started after that drive (not during, and not during the charging when I got home), and after I had pushed the plastic duct housing sort of back in place (not totally attached, but a lot closer), but before the PEM fan connector was replaced (it was connected, but without the rubber housing). They have continued after the connector was replaced and housing was properly attached.

So if it's electrical, and if they replaced the entire connector (pins and housing), then perhaps the connector isn't seated properly? That would be unlikely, since the behavior didn't change after the connector was replaced. Hopefully the PEM (male) pins aren't damaged. That would be significantly harder for them to fix.

The final odd thing... It's been very consistent now, whenever the car charges, I get an 1146 alert right AFTER the charging is finished, with a lag of maybe ten seconds. OVMS beeps with the charging complete event, then less than a minute later another beep with the 1146. Why then?
 
A theory.

The misaligned duct made the fan struggle harder =drawing more power/amps =the connectors then was burned/overloaded so then they had/have less good mechanical contact than before. But then I read that they have changed the connectors but this overload could have happened anywhere in the ”chain” that ends with the fan(s).
 

gregd

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Dec 31, 2014
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Additional info (so, a question). I've come back from a Drive Electric Week event (the Roadster was the "eye candy" to bring folks in, and it did that job very well), and the car is charging. I've got the OVMS "Dashboard" running on the PC (web browser into the module), and when the alerts come up (there have been several during the charging, usually coinciding with some of the HVAC runs, which is odd * ) there is an additional bit of information: 1146 2097152

What does the "2097152" part decode to?

(*) They also appear to be every 10 minutes... What happens every 10 minutes?
 
A theory.

The misaligned duct made the fan struggle harder =drawing more power/amps =the connectors then was burned/overloaded so then they had/have less good mechanical contact than before. But then I read that they have changed the connectors but this overload could have happened anywhere in the ”chain” that ends with the fan(s).

This theory is not correct. An electric motor draws less current if you block free air flow. Look at the characteristics of the power-rpm curve
If the fan gets dirty then the airflow is reduced, hence the current goes down, hence an alarm is produced by the computer.
This is in basis a good system.
However since the connectors are crap the current is reduced because of contact resistance and an alarm is produced based on this phenomenon.
 
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This theory is not correct. An electric motor draws less current if you block free air flow. Look at the characteristics of the power-rpm curve
If the fan gets dirty then the airflow is reduced, hence the current goes down, hence an alarm is produced by the computer.
This is in basis a good system.
However since the connectors are crap the current is reduced because of contact resistance and an alarm is produced based on this phenomenon.

In that case there would be more current draw since the loose duct would allow more air flow due to the excessive leakage-the air passage in the PEM is pretty small.
 

markwj

Asia Pacific
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Apr 10, 2011
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There is a reason it is a DMC alert (only shown in debug mode). Every roadster log and roadster I look at has thrown this code at one time or another.

The car measures current draw from the fans, and if that goes out of threshold, these 1144, 1146 alerts are raised.

However, there is considerable variance amongst individual cars (related to the ducting arrangement, version and individual characteristics of the fans), and imho the thresholds are resulting in false positives. Probably why Tesla left them as DMC codes, never intended to be seen by the end user.
 
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gregd

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Dec 31, 2014
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Thanks for the assurance, Mark, but we're all perhaps a bit sensitive to the PEM fan connector issue, and something definitely changed for the worse on my car as a result of the "service" performed. My conclusion as a result of this thread is that either pin 1 or 3 (or both) on the fan connector is not making proper contact, and will eventually lead to a connector failure if not fixed. If it's not electrical, then something wasn't done properly in terms of the cleaning. Either way, I really want it fixed.

That said, and thinking back a few years, my first experience with The Connector was when it was giving some mix of both 1144 and 1146 alerts, with the 1144 alerts being reported to the driver. I'm still a bit unclear about the difference between 1144 and 1146, and why one would be reported and the other not. In my twisted logic, I have been assuming that some vestigial code remains from the original 2-motor-2-fan design, and that the part responsible for monitoring the motor fan is what is being triggered. I've had no 1144 errors this time around.

I've got an appointment next Monday to take the car back in... Fingers crossed.
 
make it short:

the molex-socket for pem-fan connection is under-dimensioned. the radial-spal-fan (2.0 and 2.5 only) pulls max. up to 20 amps, the socket is engineered for a max of 18amps. the original socket lasts for a while, but especially ejecting and plugging the plug (as at service) will wear them off.

replacing the female plug only won't help you for a long time, as the socket in the pem also wears off.

only help is a replacement with better material - please check pics in german TFF-forum:

Lüfter tot - PEM zu warm - shut down! Hat jemand eine Idee? • TFF Forum - Tesla Fahrer & Freunde
 

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