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Update for the forum.


I was recently contacted by the NHTSA for further information on the loss of power due to the MSD.



Loss of Motive Power / Propulsion / Stallingfor the Chevrolet Bolt EV is part of ODI (Office of Defects Investigation) case 2385A. ODI's questions asked if the vehicle had been repaired or if there were ongoing defects. It seems very routine.




[Since the MSD failure at 22,000 miles, the Bolt has not had any problems. Battery capacity looks great, and due to a work assignment, I am using the car for a bi-weekly 400 mile commute.]


Any other members receive a confirmation?

It's heartening to see Federal regulators competently doing their job. I would not be surprised to see a Federally mandated recall on this one. There have been a handful of reports here alone, and that's too many for such a safety-critical part.
 

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Hi all,

Just registered so I could reply to this thread. I actually had the MSD fuse fail on my car while I was driving. Happened July 3rd on my way to work, in one of the worst places it could have happened... in the right turn lane that goes onto the freeway.

I was going about 35 mph and took my foot off the pedal to slow down (driving in L mode) for the lineup of cars waiting to get on the freeway. The cars in front of me stopped quicker than I expected so I used the brake pedal to slow down faster and just as I was slowing down with the brake, I felt the pedal sink down a bit as if the regen braking went away completely and then heard a ding from the car with a warning on the dash about "propulsion power is reduced". I came to a stop and the car said to put it in park, so I did. And then I tried to start again but it said something about "conditions not right for selected drive mode". I couldn't even shift it into neutral. Turning the car off and on again made no difference, but that brought up more warnings about servicing all sort of things on the car (cruise control, battery service, etc.). The range went from 244 miles down to 0, and then every once in a while would show 244 again, but eventually went to 0 for good.

Called the local police to get a car behind me with his lights on so I wouldn't get crashed into and so people would know to get over and go around me, and about 45 minutes later my tow truck finally came and towed me to the dealer. At this time, the backup that I had caused probably stretched for a mile... Sorry commuters... Anyway, the service department looked at it that day and told me the fuse in the Manual Service Disconnect failed, and that apparently there was a "bad batch" and they would be sending the old one to GM for analysis. Two days later (because of July 4th holiday) I got a new MSD and was back in business.

The scary thing was that when it failed, it lost all propulsion power. I could still steer and brake, but I was thinking that if I was on the freeway when it happened, I'd be in a very dangerous place that I wouldn't be able to get out of without a tow truck. So basically, if it happens while you're driving, get off the road as quickly and as safely as you can. Hopefully GM can determine what cars have the bad batches and issues a recall quickly.

This is almost word for word the experience my wife just had with her brand new 2019 Chevy Bolt. She had 82 miles on it, was going up a very slight grade at about 35 MPH. Total failure, absolutely no warning. We'd had it less than 72 hours. Too bad we live 20 miles north of the California state line. California gives you 72 hours to return a new car no questions asked. Oregon only has a "3 strikes and you're out" lemon law. Who wants to have 3 life-threatening fuse failures? Our local Chevy technician diagnosed it as the MSD fuse. He replaced it and the car runs again. When I asked him why it happened, he just said that there was probably a bad batch of fuses. He said that Chevy and the manufacturer (Eaton) had probably corrected it. When I pressed him a bit more, he said that there was a TSB on this problem: the same 18-NA-225 that others here have cited. I have yet to see a copy of that TSB. I have also not pursued it with the Transportation Safety Board although I see a reference to an open case in the forum. It strikes me as very improbable that there would be repeated "bad batches" over 3 model years. Like others here, I am also concerned that there is an underlying failure in the electrical system that is triggering the blown fuses. Any further news/solutions from anyone following this thread?
 

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I am also concerned that there is an underlying failure in the electrical system that is triggering the blown fuses. Any further news/solutions from anyone following this thread?
By design, they're a weak link. Hard to test them without shortening their life even further. I'm thinking of buying a spare fuse one of these days. Probably before a cross-country trip. Maybe one day they will design a resettable breaker instead of a fuse.
 

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Thanks for the reply. I'm not so worried about fixing it as understanding why it keeps happening across 3 model years. I'm also worried about it happening again. We live in a mountainous area; there is no room for this kind of no-warning complete engine failure.
 

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Discussion Starter #25
This is almost word for word the experience my wife just had with her brand new 2019 Chevy Bolt. She had 82 miles on it, was going up a very slight grade at about 35 MPH. Total failure, absolutely no warning. We'd had it less than 72 hours. Too bad we live 20 miles north of the California state line. California gives you 72 hours to return a new car no questions asked. Oregon only has a "3 strikes and you're out" lemon law. Who wants to have 3 life-threatening fuse failures? Our local Chevy technician diagnosed it as the MSD fuse. He replaced it and the car runs again. When I asked him why it happened, he just said that there was probably a bad batch of fuses. He said that Chevy and the manufacturer (Eaton) had probably corrected it. When I pressed him a bit more, he said that there was a TSB on this problem: the same 18-NA-225 that others here have cited. I have yet to see a copy of that TSB. I have also not pursued it with the Transportation Safety Board although I see a reference to an open case in the forum. It strikes me as very improbable that there would be repeated "bad batches" over 3 model years. Like others here, I am also concerned that there is an underlying failure in the electrical system that is triggering the blown fuses. Any further news/solutions from anyone following this thread?
Prior to setting up a case with Chevrolet make sure you cover your bases well. I am the OP and can report the following:

My 2017 BOLT EV has over 45,000 miles, no meaningful battery degradation, and no problems with the MSD since the replacement.

This is a rare occurrence. Simply look up the reports on the NHTSA database. They are public knowledge. Please scroll to the bottom of the page: https://www.nhtsa.gov/vehicle/2017/CHEVROLET/BOLT/4%2520DR/FWD#complaints. Of the 12 total power losses, only 1-2 may be the MSD. (You should also report yours!)

There is significant engineering discussion that high-current fuse fatigue does occur and can lead to increased internal resistance of the fuse. The BOLT does not need a 'blown fuse' to shut down; it only needs to believe there is increased battery resistance. Please see https://www.chevybolt.org/threads/bolt-lost-power-while-driving-on-the-highway.29615/post-434689. There may be some manufacturing conditions that lead to increased fuse fatigue, but these may not be known nor communicated by the fuse manufacturers.

The problem with doing anything other than demanding your warranty be honored or applying state consumer laws is that you are grasping at mist with an MSD failure. It is very hard to improve designs that fail in the part per ten-millions range, even all parties were acting in good faith. It's even harder to prove GM was intentionally acting negligently given the nature of the failure.

Get the MSD replaced and enjoy the car. I know it took me about a month to stop looking at the power meter...

Extra credit--Change the MSD fuse with a Pyro Fuse as used by Tesla. https://www.pyroswitch.com/protective-potential/ Pyrotechnic fuses are definite acting devices. An electrical current signal physically fires a squib that forces a guillotine blade to sever the fuse element. No doubts and no metal fatigue!
 

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Thank you very much for this response. I have read through all of the NHTSB complaints. (I also filed my own.) If we pick the car back up, we will probably only drive it on surface streets at 25 MPH -- with our Toyota RAV 4 hybrid trailing. Hopefully we will have our confidence restored like yours was.
 

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Discussion Starter #27
Thank you very much for this response. I have read through all of the NHTSB complaints. (I also filed my own.) If we pick the car back up, we will probably only drive it on surface streets at 25 MPH -- with our Toyota RAV 4 hybrid trailing. Hopefully we will have our confidence restored like yours was.
You are welcome, and good work in adding to the NHTSA database.

I do like your trial plan with a backup RAV 4 as a sag vehicle. However, I would suggest a different approach with an experiment.

If you break a spoke on a mountain bike, do you put training wheels on the bike and ride it on perfectly paved asphalt? Like an MSD failure, you will never definitely understand why a spoke breaks... No. You put in a new spoke and do some controlled bunny jumps to make sure there is nothing else wrong. You want to show you can ride the bike, the bike is not riding you.

So...

Plan a 150-175 mile road rally with your wife, the support driver takes the RAV. Perhaps interesting loops around Ashland, Medford, and Grants Pass; all have some authorized Chevrolet dealer should the experiment need a tow.

Make sure you are always within the legal speed limit, yet max the BOLT out. You want to approach the BOLT technician with honesty, and plausible deniability should the MSD act again. "It happened again. Should I be careful when merging onto I-5?" [I won't tell you I accelerated at the Ashland on-ramp 17 times with 0-60 times in the mid 6's and the TSC trying to hold the tires on the road...the Band-Aids on my fingers? Just blisters from handling the torque steer at 150kW power..."]


Also, perform a simple experiment. I do not know how this will work out, but it should be interesting.

  1. Obtain a simple IR heat gun from Lowes, HD, or Harbor Freight. These can measure near ambient temperatures with about 5% accuracy.
  2. Remove the rear seat cushion (see this forum) to expose the MSD. This is an easy procedure and you will see (but not touch, manipulate, or lift the lever of the MSD) the orange-red MSD immediately below where the rear seat was.
  3. Test your IR gun by heating a front seat and observing the temperature rise as the seat heats up. If your IR gun can measure the few degrees of front seat heating, it can measure heating of the MSD. Forum contributors note the seat heaters draw about 85 W and spread it over the seat area. You will see this is important in step 4.
  4. Have a co-pilot in the BOLT focus the IR gun on the MSD while driving. The MSD fuse is a Bussman FWH-400 that is rated to lose 65 Watts at 400A (about 400 micro ohms maximum resistance. See the power loss specifications here). At full power, you should see warming on the order of what you saw on the heated seat.
  5. Push the car to the legal limit in your road rally. Do you see some unusual temperatures that would make you think there is more than 65W being dissipated? Call your dealer or report to the regional technical supervisor. Explain what you did. They will be intrigued.
  6. If your BOLT is solid after the trial by fire, stop at a nice restaurant/brewpub/espresso bar near a DCFC and plug in. Check the temperature of the MSD. All of the charging current needs to pass through the MSD. Heating may be evident. Again, the only problem is if it looks like it's over 65W.
  7. In all cases, replace the rear seat before going to the dealer or sitting in the rear area.
I have tested the IR gun on the seats and steering wheel. This may be good experiment and your input would help the other contributors.

Do recall that driving at the legal limit means keeping control of the vehicle. Extracting important data from the vehicles data logger while you have been extracted with the 'jaws or life' is not the preferred way of reporting in this forum.

Good luck.
 
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