New Here, A Few Basic Questions

Cannatti · July 21, 2011

Hey guys,

I have been searching around the internet for some information and noticed a few of your threads were very helpful. I figured I would join up, ask a few questions and hopefully share some information that I posses.

I just picked up a 1999 Bravada, with 120K miles on it. When buying I knew the ABS light and the Check engine light were on, Taking a seemingly trustworthy man's word for the CE light to be no O2 sensor I happily payed him the money. Fast forward, about an hour? Hah. I was pulling out a parking space and made a sharp turn. You can pretty much guess where this is going, jumping, etc I instantly knew 4wd was engaged. I pulled the 4wd fuse in order to get the truck home.

I know the majority of the time this problem is the TCCM and/or sensors. What is throwing me off is the ABS light that is also showing. My somewhat limited knowledge knows that ABS only detects front wheels, where the smart track system uses sensors for the real wheels, I do not think I am wrong?

I plan on going to Autozone and getting some codes read, right now in my mind possible suspects are some sort of ABS malfunction, TCCM, the sensors, possibly the switches? Also, I am hoping I did no permanent damage driving it in 4WD, I did drive it home, but nearly all straight aways or gentle curves. My question on this, if i did do any kind of binding etc, would I know it?

Also, there is a sound when accelerating up to about 35mph, a rattling of sorts sounds like it coming from the undercarriage, front area but not the engine. I first suspected an exhaust leak but then read about possible heat shield rattling. Any other possible culprits?

I plan on updating this post with the codes I receive, and I also plan on doing the TC flush asap. I hope to get this truck in strong working order before NE Ohio winter sets in, I hope I am not asking too much, but as a college student working through school, guessing and hoping is about the worst thing I can do for my dismal check book.

Thank you guys, any help will be extremely appreciated!

greentourismo · July 21, 2011

Well I hope you got a great deal on the truck...I think the $70 to take it to a shop would have been a great idea. That being said, its obviously too late for that. I dont know a ton about the bravada as olds isnt huge in canada but If it as the auto 4wd transfer case like the blazers I do know that the dash switches are a very common fail point.Im pretty sure that it would have 4 wheel ABS as well. I would assume you did no damage driving it in 4wd unless something broke which you obviously didnt. As for the noise, your going to have to get under it and search around, start by checking heat shields, look for signs of exhaust leaks etc.

I will also strongly recommend that you are sure of anything you are replacing and not just taking advice from "forum mechanics" who arent mechanics, and cannot see or hear the problems. I see too many people throwing parts at cars and coulda spent less taking it to a shop which they usually do in the end.

Hey guys,
I have been searching around the internet for some information and noticed a few of your threads were very helpful. I figured I would join up, ask a few questions and hopefully share some information that I posses.

I just picked up a 1999 Bravada, with 120K miles on it. When buying I knew the ABS light and the Check engine light were on, Taking a seemingly trustworthy man's word for the CE light to be no O2 sensor I happily payed him the money. Fast forward, about an hour? Hah. I was pulling out a parking space and made a sharp turn. You can pretty much guess where this is going, jumping, etc I instantly knew 4wd was engaged. I pulled the 4wd fuse in order to get the truck home.

I know the majority of the time this problem is the TCCM and/or sensors. What is throwing me off is the ABS light that is also showing. My somewhat limited knowledge knows that ABS only detects front wheels, where the smart track system uses sensors for the real wheels, I do not think I am wrong?

I plan on going to Autozone and getting some codes read, right now in my mind possible suspects are some sort of ABS malfunction, TCCM, the sensors, possibly the switches? Also, I am hoping I did no permanent damage driving it in 4WD, I did drive it home, but nearly all straight aways or gentle curves. My question on this, if i did do any kind of binding etc, would I know it?

Also, there is a sound when accelerating up to about 35mph, a rattling of sorts sounds like it coming from the undercarriage, front area but not the engine. I first suspected an exhaust leak but then read about possible heat shield rattling. Any other possible culprits?

I plan on updating this post with the codes I receive, and I also plan on doing the TC flush asap. I hope to get this truck in strong working order before NE Ohio winter sets in, I hope I am not asking too much, but as a college student working through school, guessing and hoping is about the worst thing I can do for my dismal check book.

Thank you guys, any help will be extremely appreciated!

Cannatti · July 21, 2011

Well, did some running around today. The only code I could get read was the O2 sensor, I haven't decided to bite the bullet and pay the dealership for a code read for the ABS.

I picked up 4 Qts of the Auto Track II, going to do a TC flush tomorrow, hopefully this will remedy my problem.

Also noticed today that my brakes are little weak, by noticed I mean that a normal stopping distance was allowed, but it just wasn't going to fly, ended up having to avoid a car in front of me that slammed on its brakes.

I am going to jack it up for the TC flush and the heat shield inspection tomorrow, so I will check for any damaged brake lines, I also made sure to park the vehicle in the same spot today and look for any leaks. Probably going to end up doing a master cylinder and pad (maybe rotor) swap within the week. Anybody see any errors in my logic, other things I should check while im devoting the day to working on it?

I am hoping the toughest part will be finding a shady spot to park it, its 110+ with head index today.

Thanks again.

greentourismo · July 22, 2011

good idea, throw parts at it...might as well do a brake booster, new lines, and calipers too.

seriously....you think there is a brake problem, the abs light is on......get someone who knows what they are doing to look at it. Its gonna cost less than all the useless parts you are throwing at it with your "theories"

blacksierra01 · July 22, 2011

If the ABS light is on, take it to a reputable repair shop to have it diagnosed. Trying to fix it by throwing parts at it will be a way bigger waste that getting it diagnosed by the dealership.

Doug_Scott · July 23, 2011

I am one of those that was a mechanic in the "old days" before electronics, and was working during the transition. One thing that was always stressed at those after work technical training was "look at something from the basics first". The basics are the same with or without computers. You need to see why it is stuck in 4wd. Could be as simple as a sensor, but that does not mean you put on in to see if it works now. Every component has a testing procedure, follow it.

You also need to understand that if the truck truly only needed an O2 sensor, the seller would have put it in and got more money for the truck.