Service Brake Booster on DIC in '03 Tahoe

  1. Welcome to GM Inside News Forum – General discussion forum for GM

    Welcome to GM Inside News Forum - a website dedicated to all things GM.

    You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, at no cost, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, Join GM Inside News Forum today!
     
+ Reply to Thread
Page 1 of 2 12 LastLast
Results 1 to 15 of 20

Thread: Service Brake Booster on DIC in '03 Tahoe

  1. #1
    1.8 Liter ECOTEC deelitlguy's Avatar
    Join Date
    Mar 2005
    Location
    Southern CA
    Posts
    34
    Thanks
    0
    Thanked 0 Times in 0 Posts

    Service Brake Booster on DIC in '03 Tahoe

    Hello - if this is a repeat question, apologies. I have a 2WD '03 Tahoe LT 5.3 with about 56,000 miles on it. Got a "Service Brake Booster" message on the DIC a couple times last week. Stayed on for a minute or so each time, and then went back to the odometer display. Didn't seem to be any problem with the brakes (pedal feel was fine) but I took it to the dealer to have it checked out. Dealer has had it for two days and can't figure out what's wrong with it. They also can't get the message to come back on the DIC, and told me the messages displayed on the DIC don't store as codes for the scan when they plug in the diagnostic computer.

    Anyone heard of the "Service Brake Booster" message?

    Last edited by deelitlguy; 02-07-2007 at 08:01 PM.

  2. Remove Advertisements
    GM Inside News
    Advertisements
     

  3. #2
    7.0 Liter LS7 V8 Premium Member
    Join Date
    Sep 2004
    Location
    *
    Posts
    4,467
    Thanks
    0
    Thanked 1 Time in 1 Post

    Re: Service Brake Booster on DIC in '03 Tahoe

    New one on me...maybe shadams has heard of such...

    It's possible the cluster or BCM has gone wonky on you...

  4. #3
    GMI Staff Member Premium Member shadams's Avatar
    Join Date
    Apr 2005
    Location
    Texas Hill Country
    Posts
    3,377
    Thanks
    0
    Thanked 2 Times in 2 Posts

    Re: Service Brake Booster on DIC in '03 Tahoe

    That vehicle has whats called a supplemental brake assist motor, it is a extra vacuum pump to supply extra vacuum in low vacuum conditions such as accel or if the booster failed. It runs a self test every time you start the vehicle for 1 second, and if the IPC (instrument panel) does not see that the test completes 5 times in a row it turns on the "Service Brake Booster" message.

    When you start the vehicle and get to around 10 mph you should hear a light buzzing noise, maybe even feel it in the brake pedal. If that isnt happening then the SBA motor may need to be replaced. If it is coming on and the message appears, it may need an instrument cluster, but there are other reasons it could come on, see following:

    The Supplemental Brake Assist (SBA) unit creates vacuum for the brake booster in case of a vacuum loss or low vacuum to the brake booster. The SBA consists of

    • The sensor circuit board and pressure sensor

    • The check valve manifold

    • The vacuum pump

    • The motor

    When the vehicle is keyed ON, the SBA performs a self test by toggling the Supplemental Brake Assist Signal Circuit low for one second. The instrument panel cluster (IPC) recognizes this as an indication that the SBA is functional. If the IPC does not see this signal for five consecutive ignition cycles the Service Brake Booster Message is displayed. The SBA performs diagnostics at 16 Km/h (10 mph) under normal conditions, and before 16 Km/h (10 mph) if a low vacuum condition exists. The SBA then spins the motor and runs diagnostics to determine if the pump is operating and the SBA is functional. The SERVICE BRAKE BOOSTER message will display until the next ignition cycle if the unit is unable to maintain reduced power brake levels.

    The SBA unit utilizes the ignition on signal from the generator to determine the engine is running and monitors speed using an input from the vehicle speed sensor. It also has an internal pressure sensor that compares the pressure inside the booster to the ambient pressure. If the vacuum drops below 18 cm/Hg (7 in/Hg) the REDUCED BRAKE POWER message is displayed and a 5 second timer is started. If the vacuum stays below 18 cm/Hg (7 in/Hg) for 5 seconds the SBA starts the pump. If the vacuum drops below 15 cm/Hg (6 in/Hg) the pump comes on immediately. Once the vacuum level increases to 23 cm/Hg (9 in/Hg) The pump shuts off. The REDUCED BRAKE POWER message continues to be displayed until the vacuum level reaches 25 cm/Hg (10 in/Hg). If the pump runs for one minute without the vacuum reaching 23 cm/Hg (9 in/Hg) the pump shuts off and the SERVICE BRAKE BOOSTER message is displayed.

    The SBA assembly operates in two modes.

    • Low Vacuum Mode -- The low vacuum mode can occur with the engine ON or OFF. The SBA determines the ON/OFF status by monitoring the regulator output on the engine ON circuit. This mode involves SBA pump activation and deactivation due to changes in vacuum detected by the pressure sensor.

    - Low Vacuum Engine ON Mode -- The SBA will operate in reaction to changes to brake booster vacuum as monitored by the pressure sensor. This mode is normally active on power up if a valid engine ON signal is detected and a low vacuum condition is indicated for more than 5 seconds.

    - Reduced Brake Power Mode -- When the booster vacuum drops below 18 cm/Hg (7 in/Hg) the SBA will start a 5 second timer. If the vacuum exceeds 18 cm/Hg (7 in/Hg) the timer stops and resets. After 5 seconds the pump activates and the REDUCED BRAKE POWER message is displayed.

    - Immediate Pump Activation Mode -- When the booster vacuum drops below 15 cm/Hg (6 in/Hg) the REDUCED BRAKE POWER message is displayed and the pump is turned on.

    - Pump Deactivation Mode -- The pump will be turned off when the booster vacuum exceeds 23 cm/Hg (9 in/Hg). The SBA will continue to display REDUCED BRAKE POWER until the booster vacuum exceeds 25 cm/Hg (10 in/Hg).

    - Low Vacuum Engine Off -- The SBA will monitor the vacuum when the vehicle is above 8 Km/h (5 mph) and an engine OFF condition is detected. If the vehicle is below 8 Km/h (5 mph) and an engine OFF condition is detected the SBA will monitor the vacuum for 60 seconds

    • Vacuum Augment (Engine OFF) Mode -- If the engine ON state changes to OFF after reaching 8 Km/h (5 mph) the SBA activates the pump for up to 60 seconds. After 60 seconds the pump shuts off and the SERVICE BRAKE BOOSTER message is displayed. If the engine ON signal is detected or the vehicle slows to below 8 Km/h (5 mph) before the pump times out. The pump shuts off and no message is displayed.


    If everything checks out with the dealer than it is hard to point at any one part thats bad, intermittant conditions are the worst. Good Luck!
    "Contrary to common belief, planning is complicated and is not run by complete idiots, so you'll just have to trust that the decisions were made on good information that's not made available to you."

  5. #4
    1.8 Liter ECOTEC deelitlguy's Avatar
    Join Date
    Mar 2005
    Location
    Southern CA
    Posts
    34
    Thanks
    0
    Thanked 0 Times in 0 Posts

    Re: Service Brake Booster on DIC in '03 Tahoe

    Thanks very much for the info. I'll take it to the dealer and see what they say - I was hoping I didn't end up with a wacky IPC, as I've heard horror stories about them, and what happens when you get on the remanufactured loop. Hopefully that's not it. It's day three at the dealer, so maybe they'll figure something out by now - they told me they've seen this problem on medium duty trucks, but never on the light duty line. Weird.

  6. #5
    GMI Staff Member Premium Member shadams's Avatar
    Join Date
    Apr 2005
    Location
    Texas Hill Country
    Posts
    3,377
    Thanks
    0
    Thanked 2 Times in 2 Posts

    Re: Service Brake Booster on DIC in '03 Tahoe

    Quote Originally Posted by deelitlguy
    Thanks very much for the info. I'll take it to the dealer and see what they say - I was hoping I didn't end up with a wacky IPC, as I've heard horror stories about them, and what happens when you get on the remanufactured loop. Hopefully that's not it. It's day three at the dealer, so maybe they'll figure something out by now - they told me they've seen this problem on medium duty trucks, but never on the light duty line. Weird.
    Instrument clusters are probably the easiest repair there is, if they mess that up run for the hills. Hopefully they get it fixed.
    "Contrary to common belief, planning is complicated and is not run by complete idiots, so you'll just have to trust that the decisions were made on good information that's not made available to you."

  7. #6
    1.8 Liter ECOTEC deelitlguy's Avatar
    Join Date
    Mar 2005
    Location
    Southern CA
    Posts
    34
    Thanks
    0
    Thanked 0 Times in 0 Posts

    Re: Service Brake Booster on DIC in '03 Tahoe

    Well, I got it back from the dealer today. Couldn't find anything wrong with it. Dealer drove it 25 miles, couldn't get it to display the message on the DIC, and the computer scan didn't show any codes. Very strange. Service manager said the brake system looked normal, and not to worry about it. If the message comes back, I'm supposed to bring it back in. Not much else I could do - nothing I can push for fixing, since it could be so many things - just a little unsettling, wondering if the brakes will crap out every time I hit the pedal. Please continue to post, if anyone else had this problem. Thanks!

  8. #7
    Walking
    Join Date
    Feb 2007
    Posts
    1
    Thanks
    0
    Thanked 0 Times in 0 Posts

    Re: Service Brake Booster on DIC in '03 Tahoe

    I have a 2004 GMC Yukon XL. I took my Yukon in last week because my speedometer stopped working. They replaced the speedometer cluster and now I have no problems with the speedometer. But the same day I got my Yukon back, I noticed a "Service Brake Booster" on the display. Unlike the previous post, my message does not go off. Can anyone tell me what this means?

  9. #8
    GMI Staff Member Premium Member shadams's Avatar
    Join Date
    Apr 2005
    Location
    Texas Hill Country
    Posts
    3,377
    Thanks
    0
    Thanked 2 Times in 2 Posts

    Re: Service Brake Booster on DIC in '03 Tahoe

    Quote Originally Posted by TrekkerD
    I have a 2004 GMC Yukon XL. I took my Yukon in last week because my speedometer stopped working. They replaced the speedometer cluster and now I have no problems with the speedometer. But the same day I got my Yukon back, I noticed a "Service Brake Booster" on the display. Unlike the previous post, my message does not go off. Can anyone tell me what this means?
    They probably installed the wrong software that runs the cluster. It is looking for a signal thats not there because the vehicle is not equipped with it. The SUV's have hydro-boost braking/steering instead of vacuum boost. Take it back and they will have to re-program the cluster.
    "Contrary to common belief, planning is complicated and is not run by complete idiots, so you'll just have to trust that the decisions were made on good information that's not made available to you."

  10. #9
    Walking
    Join Date
    Jul 2008
    Posts
    1
    Thanks
    0
    Thanked 0 Times in 0 Posts

    Re: Service Brake Booster on DIC in '03 Tahoe

    Anyone have any further information on this? I have an 04 Tahoe that has been in the shop 5 times for this particular problem. They have replaced the IPC and or the SBA several times with no good results. I can trip it any time they fix it simply by Starting the car with a door open or triggering the IPC in any way. Once I do this the "Service Brake Booster" signal will come on and stay on forever.

  11. #10
    Banned
    Join Date
    May 2008
    Location
    pennsylvania
    Posts
    158
    Thanks
    0
    Thanked 0 Times in 0 Posts

    Re: Service Brake Booster on DIC in '03 Tahoe

    Quote Originally Posted by Sprucegoose View Post
    Anyone have any further information on this? I have an 04 Tahoe that has been in the shop 5 times for this particular problem. They have replaced the IPC and or the SBA several times with no good results. I can trip it any time they fix it simply by Starting the car with a door open or triggering the IPC in any way. Once I do this the "Service Brake Booster" signal will come on and stay on forever.
    sounds like ipc could have wrong calibrations possibly,

  12. #11
    Walking
    Join Date
    Dec 2008
    Posts
    1
    Thanks
    0
    Thanked 0 Times in 0 Posts

    Re: Service Brake Booster on DIC in '03 Tahoe

    i have a 2003 silverado and have a problem thats close to yours but for mine, it started three days ago i started the truck and that message showed up saying service brake booster for a few seconds then it shut off,so i turned it off and started it up again and it didnt show up any more.Now just today it did it again, turned off in a few seconds but only this time it happens every time i turn on the truck. did you find out what was wrong with your tahoe or does any one have an idea of whats wrong with mine

  13. #12
    Walking
    Join Date
    Dec 2008
    Posts
    1
    Thanks
    0
    Thanked 0 Times in 0 Posts

    Service Brake Booster in DIC 2004 Tahoe

    I have a similar problem as the '04 GMC Yukon. The speedometer cluster was replaced (on a recall) a few wks ago. As I started the vehicle up to leave the dealership, the "Service Brake Booster" message appeared. I should have had them look at it immediately, but had to be somewhere. It has not shut off since.

    Has anyone had any resolution to the Service Brake Booster message? I will go to the dealership again tomorrow to have some tests run. Sounds like I need to be armed w/some good info.

    Thanks, rachel

  14. #13
    Walking
    Join Date
    Mar 2009
    Posts
    1
    Thanks
    0
    Thanked 0 Times in 0 Posts

    Re: Service Brake Booster on DIC in '03 Tahoe

    Has anybody gotten anymore info about this problem. I have a 2003 Silverado, that has the vacuum motor hanging off the booster, and today on my way home from work the Service Brake Booster message came on on the IPC and i havent been able to find any good info. I dont want to just start throwing parts at it.

    My truck has 75K miles and the guage cluster has never been replaced.

  15. #14
    2.8 Liter Turbocharged V6 SwampFoxZ71's Avatar
    Join Date
    Aug 2007
    Location
    SW PA - aka Pennsyltuckey
    Posts
    885
    Thanks
    0
    Thanked 0 Times in 0 Posts

    Re: Service Brake Booster on DIC in '03 Tahoe

    Quote Originally Posted by HotRodV6 View Post
    Has anybody gotten anymore info about this problem. I have a 2003 Silverado, that has the vacuum motor hanging off the booster, and today on my way home from work the Service Brake Booster message came on on the IPC and i havent been able to find any good info. I dont want to just start throwing parts at it.

    My truck has 75K miles and the guage cluster has never been replaced.
    Wow, I never thought so many people would have problems w/ their DIC.

    2010 Chevy Cobalt LT
    2010 Subaru Impreza

  16. #15
    1.8 Liter ECOTEC deelitlguy's Avatar
    Join Date
    Mar 2005
    Location
    Southern CA
    Posts
    34
    Thanks
    0
    Thanked 0 Times in 0 Posts

    Re: Service Brake Booster on DIC in '03 Tahoe

    Had some lights go out in the IPC about six months ago, and it was replaced at the dealer. No messages since...

  17. Remove Advertisements
    GM Inside News
    Advertisements
     

Quick Reply Quick Reply

Register Now

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.


Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Posting Permissions

  • You may post new threads
  • You may post replies
  • You may not post attachments
  • You may not edit your posts
Powered by vBadvanced CMPS v4.1.2