2011 Chevy Equinox unlocks and locks doors and goes into neutral..
September 6, 2022 1:40 PM   Subscribe

intermittent problem with no codes being displayed. Sometimes it doesn't happen when driving, other times it can occur several times in a drive. Behavior: While driving the doors unlock and lock and car goes into neutral for a couple of seconds. The engine revs super high. A second or two later it recovers and drives normally. Ideas? Thank you!!
posted by bleucube to Travel & Transportation (10 answers total)
I'd check to see if there are any open recalls using the lookup tool at nhtsa.gov. That's a serious safety issue, so if it's not a one off there was probably a recall for it.
posted by wierdo at 1:46 PM on September 6, 2022 [1 favorite]

Tow it to a shop and get it looked at. I would not operate a vehicle that puts itself into neutral or other gears it shouldn't whilst driving.
posted by They sucked his brains out! at 2:01 PM on September 6, 2022 [11 favorites]

I would take it to the dealer to ask about recalls. If there _is_ a recall, the dealer will be fixing it for free. My initial thought is that the safety circuit which locks the doors once you get to 10MPH or so is messed up. That's the only thing that I can think of that relates transmission and door locks. Note - I am not a mechanic, I just had a Dad and have 4 brothers who are, so I've absorbed some stuff.
posted by TimHare at 2:05 PM on September 6, 2022

It's an automatic, yes? Transmission.

It sounds like it's dropping out of gear and into Neutral, and as a result the doors unlock because Neutral gear tells the electrics that it's safe to do so. The engine revving sounds to me like the gear's not engaged (as being in neutral indicates), but then it jumps back into gear when the speed and synchro match up just right. From what you describe, it pops out of drive and "down" to neutral (rather than "up" into neutral from a low gear). So when the engine slows due to inertia/friction, it eventually finds the place where the gears match up again and engages.

Is it cold where you are? Does it happen when it's particularly cold or hot out?

Try to note the speed and tachometer when this happens, and see if there's any consistency about it. (But also, yeah, bring it to the dealer. Being unexpectedly in neutral at speed can be dangerous.)
posted by cocoagirl at 2:41 PM on September 6, 2022 [7 favorites]

My money is on a bad ground or charging system issue. Low voltage may be confusing the BCM (body control module= door locks and many other things) and the TCM (transmission control module.) Ideally someone would do a visual inspection of battery cables, ground straps, etc and then use a more sophisticated scan tool that can monitor live data to see what is commanding the transmission to shift to neutral. It would also be an interesting experiment to try driving the car in a gear other than Drive to see what happens... do you have a D3 position or anything like that?
posted by Larry David Syndrome at 3:52 PM on September 6, 2022

Or rodents have disrupted wiring.
posted by Oyéah at 4:58 PM on September 6, 2022 [2 favorites]

Not sure what's going on with the transmission issue, but if you don't want the doors to unlock when this happens check your manual. Many cars have different settings available for door locking and unlocking, the doors are probably unlocking because the car is switching into neutral but you might be able to change that.

You should still figure out what's up with the transmission, but if it takes some time to deal with that you can at least not have to worry about door lock safety issues on top of that.
posted by yohko at 5:14 PM on September 6, 2022

It sounds like a ground issue or a short-circuit that is triggering multiple actions incorrectly. Even if there's no check engine light, the BCM or TCM may be setting 'pending' codes where there is an intermittent issue. I suspect grounding because there are at least two different control modules involved here.

Take it to a reputable mechanic. Dealer would be good because they are more likely to be aware of known issues with that particular model, but they'll charge you an arm and a leg and a good mechanic will be more willing to chase down weird issues.

This suggests you're not the first person this has happened to, so it may be a known issue.
posted by dg at 5:49 PM on September 6, 2022

You have a wiring problem. Unfortunately, this is a transient problem and tracking it down will involve a lot of testing. I'd check harnesses, and/or check circuit diagrams to see what do your symptoms have in common and is handled by which bus / cable bundle in the vehicle and try to narrow it down that way. It can be costly.

You need a mechanic who is willing to read the codes off all the different modules in the vehicle, and this *can* get costly as you pretty much need a GM specialist who has the right connectors and diagnostic modules for doing this.
posted by kschang at 3:19 AM on September 7, 2022

Response by poster: Thanks, everyone! Will take it to the dealership. I've checked the battery and grounds and all looks good. Live in Michigan, it's been hot and cold. It happens at any speed. I've added some transmission fluid (can't tell if it's low because there is no dip stick in this model).
posted by bleucube at 7:13 AM on September 7, 2022

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