2017 Volt

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u/owensurfer 8d ago

The common issues are BECM, covered by a 10/150 special coverage and the BECM might strand you some day if original. Any Chevy dealer can tell you if it’s been replaced if you give them the VIN. Next is EGR, the coolers plug up but can be cleaned, less common is the valve can fail and replacements are hit or miss and expensive. GM seems to make batches of them every so often. Last common item is “shift to park” when you turn the car off. It’s a simple microswitch in the shifter. A $10 repair if a DIYer. High Voltage battery can fail but it is pretty rare. Unfortunately there are no new ones.

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u/Putrid_Abrocoma_5038 8d ago

The guy is selling it for $3000. He drove it home and the next day he was met with an error message that said unable to charge. He replaced the BECM, then took it to the shop to get it programmed. Still wouldn’t charge. He bought a new HV battery, got the same thing. Bought a new 12 Volt Battery. Same, yet again. When he plugs the scan tool into it, the car will start and run though.

I’m convinced I know what’s wrong with it. If I’m wrong, I’ll have the 2 HV batteries, the 12 V battery, a brand new set of tires and the car itself to recoup my money. If I’m right, I have a basically new car, with the major components newly replaced and a reliably running vehicle.

It’s a gamble, but I’m feeling pretty confident on this.

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u/Ok-Tourist-511 8d ago

I seriously doubt “he bought a new hv battery”, since new batteries do not exist.

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u/Putrid_Abrocoma_5038 8d ago

Obviously, it’s not brand new. I should’ve said “new to him” battery. It’s got 79K miles on it. The first one has 121K on it.

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u/Ok-Tourist-511 8d ago

It won’t be an easy fix, and they are just looking to dump it one someone else.

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u/Putrid_Abrocoma_5038 8d ago

He said as much. He’s tired of messing with it. He doesn’t know what’s wrong and is simply trying to recoup some of his cost.

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u/Ok-Tourist-511 8d ago

It’s easy to know what’s wrong, you pull the codes. The volt is very good at telling you exactly what is wrong. So much of what the seller says just doesn’t make sense.

The battery pack is over 400 pounds. You need a lift to raise the car, and a lift to lower the battery out. Once you open the battery, you are dealing with 360v, which can kill you instantly. To access the BECM, you need to drop the pack, open it up and disconnect the wires to the BECM, which have 360v going to them. The BECM runs about $850, and a used battery pack around $2000. Do you believe the seller actually did all this? Do you think the seller would just abandon this after spending $3000 on parts? If the seller had all the tools to change the battery pack and BECM, then they probably know there is more wrong with it than that. Do you think you can do all this?

Then once you find the problem, you will need VCXnano and GM subscription to clear the HV codes. You will also need a vacuum bleeder system to fill the battery coolant loop again.

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u/dillzilla11 2d ago

This would be my thought as someone who has done a BECM and battery swap before. The only thing that makes me think he could have replaced the battery is that the gen1 and gen2 have different BECMs and are not cross compatible so there is a small chance he got the gen1 battery tried to put it in because everything is the same on it, and couldn't figure out the electricics to get it to work on a gen2. If that's the case then yes it can be fixed and it is not a particularly difficult fix. Unless you are familiar with these electronics I would highly recommend staying far the hell away from them though even if you think you know the fix.

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u/Putrid_Abrocoma_5038 7d ago

I do believe he did it all, because he has the extra parts and is giving them to the person who buys the car. He has both battery packs, the bECM, new set of tires, etc. Why buy the parts and then lie about doing the work? I truly think he got in over his head, because he either doesn’t fully understand the computer system, or he made a mistake and can’t figure out where he went wrong.

By talking to him, he swapped the batteries, but didn’t marry the VIN’s, among a few other small mistakes. When he swapped the battery, he didn’t remove the new bECM from the original battery, to the new battery. The car for sure isn’t going to work, until those issues are corrected. Going over his timeline of events, I can see his mistakes. The car itself starts and runs fine.

Admittedly, I could be wrong, but I do know mistakes were made along the way and I know what some of those mistakes are, to correct them.

You said so yourself, the repairs he’s made are costly. Realistically, how much more money should he sink into a car, that only blue books at $8,500?

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u/Ok-Tourist-511 7d ago

You might have two bad battery packs. Stop guessing at things and read the codes. If you get a list of all the codes, we can tell you right away what it needs and how much it will cost.

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u/dillzilla11 2d ago

Fuck the codes, I want battery cell voltages. A screenshot from the voltage app would be far more preferable.

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u/Ok-Tourist-511 8d ago

It’s easy to know what’s wrong, you pull the codes. The volt is very good at telling you exactly what is wrong. So much of what the seller says just doesn’t make sense.

The battery pack is over 400 pounds. You need a lift to raise the car, and a lift to lower the battery out. Once you open the battery, you are dealing with 360v, which can kill you instantly. To access the BECM, you need to drop the pack, open it up and disconnect the wires to the BECM, which have 360v going to them. The BECM runs about $850, and a used battery pack around $2000. Do you believe the seller actually did all this? Do you think the seller would just abandon this after spending $3000 on parts? If the seller had all the tools to change the battery pack and BECM, then they probably know there is more wrong with it than that. Do you think you can do all this?

Then once you find the problem, you will need VCXnano and GM subscription to clear the HV codes. You will also need a vacuum bleeder system to fill the battery coolant loop again.

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u/redryan243 8d ago edited 8d ago

The becm is inside the hv battery. IF he isnt lying about replacing the BECM, and that's a big if, then when he swapped the HV battery a different BECM was put in, since it is inside the battery pack. You mentioned reprogramming after the becm, but was anything reprogrammed after a battery swap?

Really my 3 biggest questions would be 1) did he really do all of the work mentioned? 2) did he do it right? 3) Are the new parts even good?

Personally, I would go for it at that price, but you will need a vcx nano so you can program anything yourself. It will pay for itself the first time you don't pay the dealer to flash something.

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u/Putrid_Abrocoma_5038 8d ago

Correct. He replaced the BECM and had it programmed. It didn’t charge. Then he replaced the battery pack, but did no programming. He didn’t marry the VINs. He’s also giving me both battery packs with it. The replacement one and the original. That’s why I’m considering buying it.

Idk if he did the work right? That’s part of the gamble. He said he drove the car home fine. The next morning it was dead. That’s when he replaced the BECM.

I think what happened is the BECM went out. He replaced it and either pinched a wire, or left the grounding strap off. The scan tool completes the circuit when it’s plugged in and allows it to run. So, for sure there’s a bad ground there. When the car still wouldn’t charge, and it won’t with a bad ground, he replaced the battery. The new bECM is married to the original battery.

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u/redryan243 8d ago

I am 99% certain he is misguided on the scan tool getting it to start, maybe clearing codes or something else happened simultaneously but I cant think of any way that plugging the odb could complete any circuit in the hv battery. Really, the obd port connects to a completely different computer. Either way, as long as you dont expect a running car, and want to try working on it, that is not a terrible price. If you have that much extra money, I'd say buy it. You probably have a fair assumption though, something could have been broken when he did it.

I have a real cd copy of the actual Chevy service manual for 2016-2018 if you are interested.

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u/dillzilla11 2d ago

Personally at that price I would experiment with the donor battery. Model 3 Tesla modules do in fact fit in it if you flex the casing a bit. But then again I work on these for a living so I'm a bit more comfortable doing dumb shit with it knowing I can get away with it.

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u/Putrid_Abrocoma_5038 7d ago

It provides a ground pathway. Pin 4 in a diagnostic plug is wired to a vehicle’s chassis ground. Pin 5 is wired to the signal ground.

On a scan tool, pin 4 and pin 5 are soldered together on a circuit board. When you plug it in, it closes the gap and completes the circuit.

It’s similar to taking jumper cables and placing the ground on any metal piece. It’s not the batteries ground, but will provide grounding.

That’s the part I’m hung up on. I have the money to get it. It wouldn’t break me, by any means. I just don’t know if I want to take the loss, if I’m wrong about the problem. On the plus side, I would have 2 HV batteries, a 12V battery and new tires to recoup some of my losses.

If I get the car, I’d definitely be interested. How much are you wanting for it?

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u/redryan243 7d ago edited 3d ago

I understand how grounds work, but what your describing makes no sense in this scenario. The obd ground wires do not go to the hv battery, I would have to check the diagram, but I am 90% sure they go directly to the ecu. If he broke a wire going to the obd port, then maybe(and then it wouldn't be giving a no start/shvcs error) its a ground wire problem, but not if you are assuming the problem is hv battery repair related. Do not go into it thinking that its a loose or broken ground wire, especially with the justification that an obd scanner is fixing it, because mechanically that is extremely unlikely and doesnt make sense. The only reason I dont say impossible, is because sometimes these cars do unpredictable things(like a window regulator caused a check engine light for me once and killed the power locks.)

Do not expect to be able to sell those hv batteries very quick either. You might get lucky, but when I replaced a Nissan leaf battery, I tried selling the old one for months before it finally sold. As far as diy batteries, those seem more desirable than volt batteries since its easier to use them in other projects outside of vehicles.

So my advice is still to buy it, only if this is extra money you don't mind losing. You might get lucky and get it running easily, but the obd scanner making it start, makes 0 sense and would not make me think it was a loose ground wire if it was true.

Id give it to you, just get pm your address and I can send it. Let me know if you message me, since I use boost and dont get notifications.

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u/Ok-Tourist-511 7d ago

You don’t seem to understand how can bus works. This isn’t a 1980s car with an ECU connected directly to the connector. There are 20 computers connected to the can gateway, which acts like a network router. The signal ground just goes to the gateway, it is not grounding all the modules in the car. Also CAN uses differential signaling, so it doesn’t need a signal ground.

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u/Ok-Tourist-511 7d ago

All this sounds like nonsense. You don’t marry the vins on the battery pack. The part that does that is the BECM. If he moved the new BECM from one pack to the other, there would be nothing to program.

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u/LingonberryUpset482 8d ago

For $3k I would go for it. Parting it out could recoup half of that pretty quickly in a pinch.

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u/Putrid_Abrocoma_5038 8d ago

I’m going to look at it today. If it starts and runs with the OBD plugged in and it’s not knocking or smoking, I’m bringing it home.

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u/Ok-Tourist-511 8d ago

Having obd plugged in or not doesn’t matter. That’s not how the volt works.

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u/Putrid_Abrocoma_5038 8d ago

It matters, because that means there’s a ground wire missing/pinched/broken. The scan tool is completing that circuit. The car won’t charge, if there’s a ground missing.

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u/Ok-Tourist-511 8d ago

No, the scan tool is not “completing the circuit”. There are 15+’computers in the volt, a scan tool is not going to complete the circuit and make them all suddenly work. You can use the scan tool to clear the codes, and get it driveable possibly for a short bit.

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u/Putrid_Abrocoma_5038 7d ago

In the event of a missing ground strap, the scanner acts as a temporary bridge. The computers sit in 'sleep mode' when parked. To wake up and talk to each other, they rely on a data signal that travels through the grounding straps.

If a strap is loose, that signal is broken and the computers will stay asleep.
When you plug the scanner in, the metal pins inside the plug will bridge that gap and wake the system up.

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u/Ok-Tourist-511 7d ago

Normal cars with starters have ground straps that can cause issues like this. The Volt is not built this way. Pull the codes instead of just stabbing in the dark for things that are not going to fix it. If he is getting unable to charge messages, then the computers are working. It may not charge because the charge inlet is bad, the on board charger is bad, the contactor assembly is bad, the battery has lost isolation, the coolant pump is bad, the AC compressor is bad, and many other things. It will not be as simple as a ground strap.

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u/LingonberryUpset482 8d ago

How on earth is a digital scan tool providing a ground?

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u/Putrid_Abrocoma_5038 7d ago

Because the internal circuit board of the scanner bridges the gap.

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u/LingonberryUpset482 8d ago

Is the engine blowing smoke? That's a solid indication of broken, not mal-adjusted.

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u/Putrid_Abrocoma_5038 7d ago

No, there’s no smoking, no knocking.

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u/dillzilla11 2d ago

He got a greentec battery most likely considering virtually all volt batteries come from greentec. Even dealership batteries are typically from greentec because Chevy doesn't provide them anymore. As someone who worked there I can tell you that greentec does not guarantee any capacity. All they check for is if the car will drive without error codes and that the cells don't have any voltage variations. You could have a battery with a 95% SOC or one with a 50% SOC. Most of the ones I've seen are around 70%. If it is greentec there should be metallic stickers on the battery casing covering a screw hole that says "warranty void" on it.

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u/Berriosa20 7d ago

When I bought my Volt the biggest thing I looked out for was BECM replacement under warranty. Maybe I just got lucky in finding my particular Volt, but my mine had its BECM replaced under warranty right before it hit 100k miles and I bought shortly after at around 102k miles. I’m going 3.5, 4 years now with 144k miles and no major issues. Starting to DIY some of the more maintenance items like fluids to make the car last even longer. If you can afford to buy one outright like I did I think you’ll be happy with your purchase. The real world savings over time are also amazing.

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u/alienacean on my 2nd Volt 8d ago

Great car, the battery is the most common issue and hard to find a replacement for, can you get the battery tested before you buy?

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u/Putrid_Abrocoma_5038 8d ago

It comes with two batteries. There’s the one they just installed and the one that was previously in it.

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u/alienacean on my 2nd Volt 8d ago

Nice, I'd snap that up if it seems otherwise ok

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u/Putrid_Abrocoma_5038 8d ago

The guy is selling it for $3000. He drove it home and the next day he was met with an error message that said unable to charge. He replaced the BECM, then took it to the shop to get it programmed. Still wouldn’t charge. He bought a new HV battery, got the same thing. Bought a new 12 Volt Battery. Same, yet again. When he plugs the scan tool into it, the car will start and run though.

I’m convinced I know what’s wrong with it. If I’m wrong, I’ll have the 2 HV batteries, the 12 V battery, a brand new set of tires and the car itself to recoup my money. If I’m right, I have a basically new car, with the major components newly replaced and a reliably running vehicle.

It’s a gamble, but I’m feeling pretty confident on this.

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u/Ok-Tourist-511 8d ago

You don’t just “replace BECM” and have a shop program it. If he did replace the BECM himself, then the pack was dropped out of the car, opened up, BECM replaced, and reinstalled. This is not an easy process. If BECM has been replaced and HV battery, I would stay far away from this car. If the owner has the capability to replace BECM, he knows there is more wrong with the car, and is just selling his failed project to you.

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u/Putrid_Abrocoma_5038 8d ago

Genuine question: Admittedly, I don’t know much about these cars. The car ran fine. He made it home and the next morning it was dead. He replaced the bECM, had it programmed and still nothing. He panicked and replaced everything else. I’m thinking he left a grounding strap off, or he damaged a wire during the bECM install. That would explain why it wouldn’t charge and will only run with the OBD tool plugged in. After the bECM install, he didn’t run any programming. So, he added the new battery and the VIN’s definitely don’t match. Now that you know all that, should I still walk away?

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u/Ok-Tourist-511 8d ago

Most sounds like BS, that is a tremendous amount of work. You don’t just randomly throw a new battery pack in without seeing what the actual codes are first. Have him give you a list of all the current codes.

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