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Discussion Starter · #1 ·
Today, my wife got back with our 2018 Volt. Parked, removed her purse and FOB and then opened the rear hatch as we unloaded groceries -- all normal.

Fifteen minutes later, with my FOB in pocket, I opened the drivers door (which was locked) and the horn started honking? I Hit the lock and/or unlock FOB button and the horn was silenced. With driver door open, I went over to unlock/open the passenger door and it would not open (my FOB on my person). My wife with her FOB on her also unable to open passenger door. I then unlocked all doors using the switch on my already open driver's door.

We both entered car, both our FOBs in the car but the car would not start -- No FOB detected message on dash?! I then placed my FOB in transmitter tray in compartment between the seats and the car started. I am pausing this "novel" until I get home and turn the car off -- wondering if the FOBs will then be working normally.....stay tuned for the rest of this story!

Well, I'm back home, turned off car and all is working normally. The car locked itself after the doors were closed, and all FOBs are again working as they should.

Any comments on what caused my car to not recognize my FOBs, and why my horn started honking????
 

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a) that is indeed weird, but..

b) weird stuff happens when the fob battery is marginal, and things start being detected and not detected, moment by moment, based on REALLY trivial things, like whether there's a metal key between the fob and the dashboard. So,

c) how old is the battery in the fob? More than 18 months? Replace it then see if problems get less.

d) The Volt can be configured to arm the alarm if the doors are locked with the fob button only, and then the alarm is only turned off if the doors are unlocked with the fob button OR if the passive detection is working well. See point b. Then see point c. (oh, and from behavior I've tracked in my Gen 1, the "detect for disable alarm" is not the same detecting system as the "detect for whether to unlock the door". THEORETICALLY the "detect for disable alarm" trips first because it's only a semipassive system but it seems focused in the rear of the car, but the "detect for unlock door" is focused on the door pillar vicinity. (I can hear the proximity sensor trigger a relay in the back of the car, and it doesn't trip normally until I'm nearly at the front quarter panel from the front, but I can be a half dozen yards away approaching from the rear and hear the "tick-didid" So it becomes even EASIER to think one might be able to have a dodgy fob battery and "sneak up" on the driver door and press the button and open the door before the "disable alarm" proximity sensor hears the fob, and thereby set off the alarm.)
 

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Discussion Starter · #3 ·
Both our FOB batteries were replaced less than as year ago, but who knows how good those replacement batteries were? If it goes goofy again I will replace the batteries......thanks for spending your time reading my post and replying.
 

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a) that is indeed weird, but..

b) weird stuff happens when the fob battery is marginal, and things start being detected and not detected, moment by moment, based on REALLY trivial things, like whether there's a metal key between the fob and the dashboard. So,

c) how old is the battery in the fob? More than 18 months? Replace it then see if problems get less.

d) The Volt can be configured to arm the alarm if the doors are locked with the fob button only, and then the alarm is only turned off if the doors are unlocked with the fob button OR if the passive detection is working well. See point b. Then see point c. (oh, and from behavior I've tracked in my Gen 1, the "detect for disable alarm" is not the same detecting system as the "detect for whether to unlock the door". THEORETICALLY the "detect for disable alarm" trips first because it's only a semipassive system but it seems focused in the rear of the car, but the "detect for unlock door" is focused on the door pillar vicinity. (I can hear the proximity sensor trigger a relay in the back of the car, and it doesn't trip normally until I'm nearly at the front quarter panel from the front, but I can be a half dozen yards away approaching from the rear and hear the "tick-didid" So it becomes even EASIER to think one might be able to have a dodgy fob battery and "sneak up" on the driver door and press the button and open the door before the "disable alarm" proximity sensor hears the fob, and thereby set off the alarm.)

Wierd stuff starts happening also then the 12v battery starts going bad. I'd have that checked...pretty much any auto parts store will do it if you don't have anything to check it with yourself.
 

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We both entered car, both our FOBs in the car but the car would not start -- No FOB detected message on dash?!
...
Well, I'm back home, turned off car and all is working normally.
If it happens again, and then clears up on its own, check out this thread: 2017 No Remote Detected !
Could be the fobs' receiver. There's a Youtube video on how to replace it.
 

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Wierd stuff starts happening also then the 12v battery starts going bad. I'd have that checked...pretty much any auto parts store will do it if you don't have anything to check it with yourself.
12v failures don't cause repeating faults, though. They cause spurious stuff that goes away just as mysteriously. If you have a persistant problem, it's not the 12v.

Auto parts store tests saying your cold-cranking amps are A-OK are of no help to determining whether a 12v is functional for a Volt's purposes. The closest we got to "what reading actually matters" is the battery's internal resistance, and so far we only have data points for that of "<1 ohm is a new battery" and ">70 ohms is a failed battery" and nothing in between that would tell us anything about what "marginal, replace soon" looks like.
 

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A couple years ago I had similar problems with erratic and intermittent key fobs. New batteries did not help. I cured it by increasing the tension of the battery contacts by slightly bending them upward. Simple fix - no problems since. Might be worth trying.
 

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Discussion Starter · #8 ·
Great advice, all! And thank you. So far, no more FOB surprises, but I will keep all the comments in mind.
 

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I have found that whenever the fob stops working like I expect (including not letting me unlock the doors, or giving me the "No Fob Detected", I replace the battery and it works again. Usually over a year. Also remember there are many features in the My Chevrolet phone app that can help when the fob won't work.
 
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