Hello all, I'm new to this forum. Have had a 2010 Silverado Hybrid since August of '18. No major problems til now. Got error messages last fall that led me to replace the drivers side unit hub bearing. Repair was satisfactory. Now just today, while waiting in front of a store for the wife, had brake, ABS, and stability warnings lights come on with a good 10 seconds of warning chimes, after which brake boost went away entirely. Shutting off and restarting the truck did not alter the situation. Disconnecting the battery for a few seconds and reconnecting DID restore normal function for another 5-10 minutes of driving, and then the warnings came back and power boost went away again. My Bluetooth ALDL scanner app reported only code C121F. Can't find anything about it. No obvious leaks under hood or in front wheel wells. No obvious loose connectors at brake fluid reservoir or front wheel speed sensor. Any ideas? I have noticed vibration on braking recently. Assumed new rotors might be in order, but perhaps another wheel bearing is on it's way out. Any ideas?

 

Start with the Basic steps


How old is the battery? the 12Volt battery....

that is a good place to start I have gotten Engine control failures codes BCM faults and stall outs etc.. from a dirty battery cable
I did buy new ones IT was very very hard to find them as they don't make them anymore the ones i bought were from 2013..


I ended up Not putting the new cables in but my issue corrected


the vibration can be caused by a faulty tire, rim or other part.. does the steering wheel vibrate ?... if not then it's in the rear ?


if the CLOCK is not showing hit the menu button then display then in the lower left corner press the screen (hidden button )
type in 295660 then "ok' next should be a option to set the time and date

Tires can go bad and they can get bubble or baby bump it's hidden to the naked eye. but you can feel it by hand..



hope it fixes it another guy that was stuck in mexico had a similar issue with his cables it refused to start and threw a bunch of random codes cleaning his cables fixed it ,saved him several thousand dollars in tow truck fees to ship it to a US location for repairs and diagnostics costs....









the lugs on the battery terminal can in fact get dirty and/or damaged over time the crimp came loose.on mine..


it's a 10mm nut
disconnect both terminals before working on it since you will need something like rubbing alcohol to clean it and it's VERY FLAMMABLE WILL NEED to wait for it to dry.







:O

 

I had an issue with water intrusion on the brake control control that is mounted on the ABS unit under the truck. I had been utilizing a car wash that had a undercarriage spray that i suspect had caused the issue. I replaced the module with a part from a salvage yard and it has done well for about 4 months. However now I have a C129F code which refers to the adjustable brake pedal position sensor which my Tahoe does NOT have so i guess the module that I put on needs to be flashed or something, just strange that it took 4 months to throw a code......This particular code does not affect the power boost so this is not an emergency like last time when the module went out. I erased the code and it has not come back after a few days so if it only pops up every few months, I will keep erasing it LOL

 

just install the adjustable brake pedal ?

 

I have adjustable pedals (I think all the GM Two Mode Hybrids do?) but it does not utilize the position switch so the code seems to be a "ghost code" There is a spot for the position sensor to mount on the left side of the adjustable pedal assembly but it does not appear to have ever had that sensor from the factory.

ACDelco 25799118 GM Original Equipment Brake Pedal Position Sensor with Bolts

i guess my salvage yard module was no good or maybe this all happened because I never got that salvage ABS module programmed to the Tahoe and the computer has gone completely nuts? Who knows.... I took it to the dealer and they said to replace the ABS pump and Module. Sigh, both those parts per the dealership are Obsolete parts and unavailable.
I at that point gave up on finding anyone with enough diagnostic brainpower to do a proper diagnosis and ordered a complete ABS assembly off a 2009 Tahoe Hybrid with 134k miles in Houston. There were several up in MI and PA and NC but I figured a low mileage one outside of the of the "Rust Belt" area would increase my odds of getting a good salvage unit...........
I am Dropping it off in the morning at 9 a.m. at my local FIXIT shop to replace the entire assembly and bleed the brakes (takes a special tool to bleed the brakes electronically so they say?)
That brake position code did not come back but I now have a total of (9) ABS codes C1185 - C1198 - C1194 - C1254 - C1246 - C1250 - C1242 - C1214 and C1210
I need this Tahoe to last at least 16 more months until I retire. It has now become a challenge to keep it running smoothly but I guess at 228k miles and 11 years old some issues are to be expected. The old gal still runs great just kind of hard to get her stopped quickly right now. DO NOT EVER PULL OUT IN FRONT OF A TAHOE their dang brakes may not be working very well Hahahahahahahaha
I will try to remember to post back some pics I a of course going to keep the old ABS assembly and take it apart on my work bench I might find that the brake fluid had gotten grungy and messed up the pump and modulator valves inside it will be interesting. So WHO actually changes their Brake Fluid every 2 years???? If I tear this apart and find corrosion on the interior of the ABS valves that person changing brake fluid regularly will be ME LMFAO. Stay tuned, might be back next weekend with news and pics.

 

i would check the fuse for the ABS if you have not done it

that c1214 is stuck valves did you flush the brake lines before installing that replacement?

 

The salvage yard complete ABS assembly was put on the 2009 Tahoe Hybrid with 227k miles late yesterday at a local shop, they bled the brakes and then called me and told me that it now only has one code, which indicates that the new module needs to be programmed to the vehicle............... Hoping that they will have it ready this afternoon, if they cannot program it I may still have to go back to the dealership to have it programmed!
I told them to save the old ABS assembly for me, I am going to take it apart and do an inspection, My current theory is that the modulator internal valves may be corroded from not ever having a brake fluid flush. I will try to remember to post up some pics of what I find when I tear it down. Might be clean as a pin and there are some other issues.........Ole TaHOe is really starting to aggravate me with its constant need for attention. .

 

I was likewise worn out on the showroom not actually thinking often about my old vehicle. Last multiple times I needed to stand by above and beyond an hour to get my vehicle after the showroom said "It's prepared!".






192.168.100.1 192.168.1.1

 

UPDATE January 10th 2022 -OP will need one of these complete ABS units (obsolete part that is only available from a salvage yard) I would recommend that everyone else have their brake fluid flushed and changed regularly as a preventative maintenance item. This is about the worst thing that has ever happened to my ole 2009 hyHO over the years. Cost me a lot of time and trouble to fix this. Currently at 256k and the braking system works well after the part and fluid (to DOT 4) swap. I retired last October and sold my New Denali Truck for 9k more than I gave for it LOL so this IS my only means of current transportation. Hope everything on this ole beater ride holds together for another year till the supply chain issues ease and I can actually get a New Denali again. A bit tedious messing with ole beater rides sometimes. Currently running a homemade oil drip catch pan to capture the rear main seal leak. Not planning on ever fixing that unless it gets a lot worse.