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Discussion Starter · #1 ·
I have only had one problem with my 2018 Volt. I purchased it in Scottsdale, Arizona and during the hot time of year the Stabilitrak, brake light and service light would come on. This would be only in the hot season and mostly with the gasoline engine being used. I took it to Van's Chevy in Scottsdale (dealer) and they did not fix it. I moved to San Antonio, Texas and took it to Alamo City and they had it for several days and found nothing wrong. They did agree that the history was showing the faults but were unable to determine what component was having issues. When the Stabilitrak light is on, the brakes pulse when you are trying to stop. So I use regen braking and make that last bit of stopping with a jerk on the mechanical brakes. I do not let my wife drive it because she would become very concerned with the braking and make me get rid of the car.
Would the dealer be able to connect a mobile diagnostic system to sort it out while it is being driven? Next time I take it in I need to tell them to drive it hard with the gasoline engine on and drive it for an hour if needed to get the fault to occur. It also needs to be a hot day.
Does anyone know where the HMI computer is? I was wondering if it was getting a little too hot. This does not seem like a wheel sensor speed problem to me.
Appreciate any feedback on issue.
 

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When it comes to the wife, do not stir the hornets nest. :p:rolleyes:
 

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Mine appears on long downhill glide. But I just ignore it when I get home, recharge, and the following day, everything is back to normal.
 

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Yes -- mine had the CEL, ABS and traction control lights along with "service stabilitrak" in the DIC.
My 2018 that had all those faults lit, difficult for dealership to locate problem source; as a result, they replaced the ABS module and that had corrected these reoccurring faults.



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I have only had one problem with my 2018 Volt. I purchased it in Scottsdale, Arizona and during the hot time of year the Stabilitrak, brake light and service light would come on. This would be only in the hot season and mostly with the gasoline engine being used. I took it to Van's Chevy in Scottsdale (dealer) and they did not fix it. I moved to San Antonio, Texas and took it to Alamo City and they had it for several days and found nothing wrong. They did agree that the history was showing the faults but were unable to determine what component was having issues. When the Stabilitrak light is on, the brakes pulse when you are trying to stop. So I use regen braking and make that last bit of stopping with a jerk on the mechanical brakes. I do not let my wife drive it because she would become very concerned with the braking and make me get rid of the car.
Would the dealer be able to connect a mobile diagnostic system to sort it out while it is being driven? Next time I take it in I need to tell them to drive it hard with the gasoline engine on and drive it for an hour if needed to get the fault to occur. It also needs to be a hot day.
Does anyone know where the HMI computer is? I was wondering if it was getting a little too hot. This does not seem like a wheel sensor speed problem to me.
Appreciate any feedback on issue.
If you have OnStar service for your Volt; as a result, when fault occurs call OnStar and request they collect all the car fault codes and email those car fault codes to your email address. I understand that some car fault codes clear from memory after a number of car re-starts. As some people have noted that the next day some or all fault codes reset and go away. Best to collect fault codes as they occur while driving.


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Yup, mine has these codes:
C0506 - ???? can't find this one anywhere
P25A2 - Brake System Control Module Requested MIL Illumination

Been at the dealer 3 days so far with no update.
 

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Yup, mine has these codes:
C0506 - ???? can't find this one anywhere
P25A2 - Brake System Control Module Requested MIL Illumination

Been at the dealer 3 days so far with no update.


My codes as OnStar extracted from my Volt a couple of minutes after the faults occurred while driving. It seems my car problem solution was replace the “brake module”.


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Got my Volt back today.

Dealer diagnosed the issue as the right front wheel speed sensor. Specifically they found the "sensor cut down the middle from the axle washer". Replaced the sensor and axle washer for $200 diagnostic fee plus $250 parts/labor. Would be covered under 3/36 but I have 54k miles.

Unfortunately, they did not fix the clicking noise from the left front which was the point of my original visit before my dashboard lit up like a Christmas tree. I am now fairly certain that the LEFT front wheel speed sensor is likely the source of the clicking sound, though it makes no sense to me why the right one failed. I am fairly sure this is all described in TSB #17-NA-047 which I had to bring to the dealer's attention. :rolleyes:

Called my service advisor from the drive home and told him the clicking was still there -- he invited me to bring it back and they would look at it again.

What a PITA.
 

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SOLVED Service Stabilitrak + Forward collision system unavailable + MIL + extremely hard to press brake pedal

Short summary: I grinded a bit the brake pedal stopper and that solved the issue

Those who would like to learn more on how did I came to such a strange solution - get ready for a long detailed reading :)

My Volt is manufactured in June 2016, now about 22000 miles. I bought it repaired after collision - front passenger side was damaged. Enjoyed the first ride just after the purchase. Drove 200 miles and when only 1 miles was left to my home the read alert BRAKE appeared for couple of seconds and disappeared, then MIL illuminated, Service Stabilitrak warning displayed. When back home I observed that stop/brake lights were on after the car was shut off. I pressed the brake pedal several times, it seemed returned back as supposed. However the brake lights were still on. Then I lifted the brake pedal - brake lights turned off. I clarified that there is a pedal position sensor. I removed it - no signs of wear and tear. Tried to install it at a slightly different angle but due to plastic pin it was impossible. Normally brake light were on and could only turn off when pedal was lifted and released.

I the meantime I received the service history. Previous owner complained about the brakes @3000 miles and @17000 miles however I could not get the information on what was the complaint about in more details. The service records were telling that the dealer was not able to reproduce the problem. It was hinting that the problem was not solved and was occurring randomly. The car had the accident @21000 miles - maybe due to problems with brakes?

I found on the google that this pedal position sensor fails with two indications - the brake light does not turn on at all (in this case you can not move the gear from Park), or the brake light stays always on - that was exactly the symptoms under normal driving and brake pedal usage conditions in my case. Ordered new sensor, installed it - the problem persisted. Thus not a sensor fault. I thought something is wrong with the sensor position. I took the old sensor, cut half of the plastic pin so that I could install it at a slightly different position. It worked this time for the brake lights.

However I was test driving and the problem was getting worse - the BRAKE alarm started to appear every 10 minutes of driving and lasted longer, accompanied with alarms Service Stabilitrak + Forward collision system unavailable+ MIL. At those moments the brake pedal was extremely hard to push and was difficult to stop the car. Sometimes the brakes returned to the normal operation after several attempts to brake, sometimes only after the car was shut off and on. MIL disappeared always after three or four times when Parked the car was powered and turned off. After one of the stops with MIL illuminated I checked the brake discs - all four of them were very hot to touch as if I was racing, but I was driving very calmly. It indicated that even when the brake pedal is ion the rest position the brakes remain very slightly applied.

Then I returned to my garage and pressed the Parking brake button - the wheels locked and I could not disengage it back with the same button. Oh sht! Then I got lost. Under the bonnet I saw that ICE cooling liquid is on the very minimum level. I topped it to the norm. Then I turned on the car - MIL disappeared, parking brakes disengaged. I understood that it is nonsense to relate the ICE cooling liquid with the brakes but when you are lost you start to lose the rational thinking.

Test drove with the stupid hopes that I fixed it. The same problems again!!! Somehow brain started to join the experienced facts together and came with a brilliant idea. When all the alarms appeared during the driving, I lifted the brake pedal with my left foot and kept it the lifted position. What do you think - the alarm BRAKE disappeared after 2 seconds and the brake pedal came back to the normal state. Drove so far 5 days since - no more messages, no more alarms, no more MIL!!!

OK then the next step was to adjust somehow the brake pedal to the more retracted position. I spend several hours to figure out how to do it. Later I learned I was lucky to struggle in this particular step. In With the garage doors closed it was absolutely silent around and I could hear very important sounds with my head in the area of pedals: when brake pedal released normally I could hear something whistling as if some pump (I guess vacuum pump) still works at the engine side. When pedal manually retracted beyond the normal resting position, I could hear some valve closing. Later I learned that most probably this way I forced the brakes booster to close fully which enabled vacuum pump to stop working.
Then I decided to make the brake pedal and the booster connecting rod shorter so that the brake pedal spring would be able to retract the rod more by a tiny bit. However I failed to do it due to no access to the booster rod to keep it in order to screw in the brake pedal push rod (I guess it possible but I could not figure out how to do it).
Then I decided to do something with the brake pedal stopper at the top. I made pictures and shot video prior this. It was very strange to find the stopper of this construction - white plastic and the plastic bracket, then wire on top of the white plastic. It looks like the white plastic was repaired already and all the solution looked like home-made. Anyway my hands luckily are small and I reached to grind vey little of the steel which is in direct contact with the brake pedal. That was enough to provide more travel for the brake pedal, retract more the rod going to the booster and gain so much desired closing of the valve. After this modification I could hear the valve closing after brakes pedal released normally.

No more problems so far. Hopefully.

During those days somehow I could not connect my VCXNANO to read the DTCs, but connected today after the problem was already solved to read the stored DTCs. As I understood
- Brake Booster Control Module generated P05E0 error which means "Brake Pedal Position Sensors 1-2 Not Plausible"
- Electronic Brake Control Module generated U0452 which is "Invalid Data Received From Inflatable Restraint Sensing and Diagnostic Module"

For the brake pedal position sensor - I found a video on YouTube for Chevrolet Cruze - it is possible to calibrate it
<https://www.youtube.com/watch?v=G44bFKZHbhU>
Today when I was able to real live data - on my car it shows a position "0" now. As well I found a parameter telling what is the voltage at the sensor in the position "0" which is automatically learned (?).

The next step - I will investigate if the brake pedal stopper could misalign significantly and cause all the problems I encountered. When grinding I saw it moving to the left and right, so my suspition about it as a home-made still remains. Here I need your help - please make a picture and post it here how the stopper looks like in your Volt?

If this kind of stopper is factory made - then poor design. Then I suspect that ex-factory many cars come with poorly adjusted travel distance of the brake pedal (or to be more specific the length of the rod connecting the booster and the pedal). I assumed as well the option of worn o-rings in the booster, but I reject this option because a) some Volt owners reported the same problem very early after the brand new car purchase b) in my case initial indication of the fault was brake lights illuminated with the brake pedal in the resting position c) brake pedal stopper is very flimsy.

I hope such a long and detailed description will help someone facing the same problems in the future and hopefully will let avoid costly repair bills.
 

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can anybody make a picture of your Volt brake pedal stopper, please? its only possible with your cell phone because the access is very difficult. In my case you can see that it seems its a home-made, white plastics is partially melted, on top a metal attachment. Alternatively - maybe someone has a drawing how this part should look like?
brake pedal stopper.jpg
 

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come on guys, don't be lazy, please make a picture for me, somebody :confused:

ort at least please look at the label on the brake pedal braked behind the pedal itself - what is the part number there? In my case 23405325 but strangely Internet search does not give any suggestions
 

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Discussion Starter · #16 ·
My 2018 Volt still has the random problem with the stabilitrak and brake lights with a crazy pulsing of the brakes when they are on. I took it to a dealer in Plano, Texas and it worked ok for awhile. Took it back to Alamo City in San Antonio a number times and it did not get fixed. They had it in the shop for two weeks and thought there was nothing wrong. When I picked it up, I showed them the fault when I pressed on the brake pedal. They still think if was fixed. They do not want to swap out the module. I am bringing the car back to Van's in Scottsdale, Arizona. So I have been to three different dealers six times and no one seems to be able to fix it. Any ideas? Is there any dealer in the country that can fix these cars?
 

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Dealer diagnosed the issue as the right front wheel speed sensor. Specifically they found the "sensor cut down the middle from the axle washer".
HOLY #($Y#($Y# I have same EXACT ISSUE with my wifes 2016 premier... I pulled the wheel hub assembly off, and found the broken washer, i did notice the sensor had a groove in it, reassembled and problem still there... Now i'm thinking the broken washer cut a groove in the wheel speed sensor like yours... I have a sensor already on hand and will replace next...

20200321_160551.jpg
 

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I know from ( motorcycle ) experience...as these often have adjustable front brake levers....either hydraulic or cable/ hydraulic, where if over adjusted there can be light 'pressure' on the hydraulic master cylinder/ brake-caliper piston, which then can build more pressure.....and heat into the brake pads/disc interface.....and often, the longer and harder you drive, the more 'heat' is generated, which also leads to expansion=more pressure =more pad/disc interface.......until everything can be glowing hot to the touch

Also, sometimes if your brake calipers have worn caliper piston O rings.....when the brake lever is released the caliper piston will NOT retract ( backwards) as much as it should...leading again to sticking brakes=more heat=expansion=more pad/disc interface problems......wondering if any of these scenarios could be happening, along with the retraction of the Volts brake pedal issues...??
 

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SOLVED Service Stabilitrak + Forward collision system unavailable + MIL + extremely hard to press brake pedal

Short summary: I grinded a bit the brake pedal stopper and that solved the issue

Those who would like to learn more on how did I came to such a strange solution - get ready for a long detailed reading :)

My Volt is manufactured in June 2016, now about 22000 miles. I bought it repaired after collision - front passenger side was damaged. Enjoyed the first ride just after the purchase. Drove 200 miles and when only 1 miles was left to my home the read alert BRAKE appeared for couple of seconds and disappeared, then MIL illuminated, Service Stabilitrak warning displayed. When back home I observed that stop/brake lights were on after the car was shut off. I pressed the brake pedal several times, it seemed returned back as supposed. However the brake lights were still on. Then I lifted the brake pedal - brake lights turned off. I clarified that there is a pedal position sensor. I removed it - no signs of wear and tear. Tried to install it at a slightly different angle but due to plastic pin it was impossible. Normally brake light were on and could only turn off when pedal was lifted and released.

I the meantime I received the service history. Previous owner complained about the brakes @3000 miles and @17000 miles however I could not get the information on what was the complaint about in more details. The service records were telling that the dealer was not able to reproduce the problem. It was hinting that the problem was not solved and was occurring randomly. The car had the accident @21000 miles - maybe due to problems with brakes?

I found on the google that this pedal position sensor fails with two indications - the brake light does not turn on at all (in this case you can not move the gear from Park), or the brake light stays always on - that was exactly the symptoms under normal driving and brake pedal usage conditions in my case. Ordered new sensor, installed it - the problem persisted. Thus not a sensor fault. I thought something is wrong with the sensor position. I took the old sensor, cut half of the plastic pin so that I could install it at a slightly different position. It worked this time for the brake lights.

However I was test driving and the problem was getting worse - the BRAKE alarm started to appear every 10 minutes of driving and lasted longer, accompanied with alarms Service Stabilitrak + Forward collision system unavailable+ MIL. At those moments the brake pedal was extremely hard to push and was difficult to stop the car. Sometimes the brakes returned to the normal operation after several attempts to brake, sometimes only after the car was shut off and on. MIL disappeared always after three or four times when Parked the car was powered and turned off. After one of the stops with MIL illuminated I checked the brake discs - all four of them were very hot to touch as if I was racing, but I was driving very calmly. It indicated that even when the brake pedal is ion the rest position the brakes remain very slightly applied.

Then I returned to my garage and pressed the Parking brake button - the wheels locked and I could not disengage it back with the same button. Oh sht! Then I got lost. Under the bonnet I saw that ICE cooling liquid is on the very minimum level. I topped it to the norm. Then I turned on the car - MIL disappeared, parking brakes disengaged. I understood that it is nonsense to relate the ICE cooling liquid with the brakes but when you are lost you start to lose the rational thinking.

Test drove with the stupid hopes that I fixed it. The same problems again!!! Somehow brain started to join the experienced facts together and came with a brilliant idea. When all the alarms appeared during the driving, I lifted the brake pedal with my left foot and kept it the lifted position. What do you think - the alarm BRAKE disappeared after 2 seconds and the brake pedal came back to the normal state. Drove so far 5 days since - no more messages, no more alarms, no more MIL!!!

OK then the next step was to adjust somehow the brake pedal to the more retracted position. I spend several hours to figure out how to do it. Later I learned I was lucky to struggle in this particular step. In With the garage doors closed it was absolutely silent around and I could hear very important sounds with my head in the area of pedals: when brake pedal released normally I could hear something whistling as if some pump (I guess vacuum pump) still works at the engine side. When pedal manually retracted beyond the normal resting position, I could hear some valve closing. Later I learned that most probably this way I forced the brakes booster to close fully which enabled vacuum pump to stop working.
Then I decided to make the brake pedal and the booster connecting rod shorter so that the brake pedal spring would be able to retract the rod more by a tiny bit. However I failed to do it due to no access to the booster rod to keep it in order to screw in the brake pedal push rod (I guess it possible but I could not figure out how to do it).
Then I decided to do something with the brake pedal stopper at the top. I made pictures and shot video prior this. It was very strange to find the stopper of this construction - white plastic and the plastic bracket, then wire on top of the white plastic. It looks like the white plastic was repaired already and all the solution looked like home-made. Anyway my hands luckily are small and I reached to grind vey little of the steel which is in direct contact with the brake pedal. That was enough to provide more travel for the brake pedal, retract more the rod going to the booster and gain so much desired closing of the valve. After this modification I could hear the valve closing after brakes pedal released normally.

No more problems so far. Hopefully.

During those days somehow I could not connect my VCXNANO to read the DTCs, but connected today after the problem was already solved to read the stored DTCs. As I understood
- Brake Booster Control Module generated P05E0 error which means "Brake Pedal Position Sensors 1-2 Not Plausible"
- Electronic Brake Control Module generated U0452 which is "Invalid Data Received From Inflatable Restraint Sensing and Diagnostic Module"

For the brake pedal position sensor - I found a video on YouTube for Chevrolet Cruze - it is possible to calibrate it
<
>
Today when I was able to real live data - on my car it shows a position "0" now. As well I found a parameter telling what is the voltage at the sensor in the position "0" which is automatically learned (?).

The next step - I will investigate if the brake pedal stopper could misalign significantly and cause all the problems I encountered. When grinding I saw it moving to the left and right, so my suspition about it as a home-made still remains. Here I need your help - please make a picture and post it here how the stopper looks like in your Volt?

If this kind of stopper is factory made - then poor design. Then I suspect that ex-factory many cars come with poorly adjusted travel distance of the brake pedal (or to be more specific the length of the rod connecting the booster and the pedal). I assumed as well the option of worn o-rings in the booster, but I reject this option because a) some Volt owners reported the same problem very early after the brand new car purchase b) in my case initial indication of the fault was brake lights illuminated with the brake pedal in the resting position c) brake pedal stopper is very flimsy.

I hope such a long and detailed description will help someone facing the same problems in the future and hopefully will let avoid costly repair bills.

THE CURE TO ALL LISTED PROBLEMS WAS REPLACEMENT OF E-BRAKE BOOSTER WITH MASTER BRAKE CYLINDER AND BRAKE FLUID CONTAINER
 
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