Need a tool I can buy to read Brake faults

[Chris]

I have a Service Brake Booster message, Is there a tool such as a Tech II I can buy that will tell me what is wrong? Where can I get a tool like this or a Tech II?

[music]

Check the brake fluid level first. Did this start after the fancy alternator upgrade?

[Chris]

Yes it did. I didnt really drive much yesterday. Today I saw the message. My temp gauge fluctuates a little so I first suspected belt, but everything is tight and the fan spins. I still have brakes. I just dont know what this message is for, my scanner pulls no codes.

[gmtech4]

check owners manual for more info on messages

[Chris]

No owners manual.

 

Fluid level is between the lip and the line for Max

[music]

My guess will be a poor or noisy ground, or it's possible that the alternator is putting out a noise of some type (or worse... the wrong voltage). Most sensor outputs get passed via the GMLAN to one of the computers, which monitors things. Problems detected = message. Anything that messes w/ the GMLAN data transmission (similar to your computer network), can cause crazy things to happen. Bad ground is easy to cause, but the alternator isn't off the table at this point. You may even see other messages, random guage behavior, etc. Considering that you just changed the alt and added some wires, you have to suspect those things first.

[Chris]

I added wires, left the stock in place as well.

[txab]

Ever used google?

 

 

https://www.google.com/search?q=service+brake+booster+2004+tahoe&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a

 

 

http://www.gminsidenews.com/forums/f53/service-brake-booster-dic-03-tahoe-44600/

[Chris]

Yes I have used google, and i have been trying to find a good answer on there.

[txab]

That 2nd link I posted is right on mark for you. But with the search I linked there are plenty of other threads to look at

[Chris]

Celt the booster in the pedal trying to pump as I drove down the freeway. My cluster shut down again while I was driving. Dic shut off and the gauges stayed where they were until I shut it down. Amplifier fuse has blown as well.

 

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[BlackZ71Silverado]

Did you hook the new wires to a new ground, or just pile them all on top of each other???

[Chris]

Took a grinder to an existing ground to remove paint. And used that ground. It was near the front of the frame next to the fog light. The original power and grounds are in place

 

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[Chris]

From reading more about the issue because I get a "battery not charging" message but I show over 14 volts while running. I'll have the alt and battery tested tomorrow. I'm going to call the place I got my alt from on Monday as well. Alternator and ground issues can cause the issue showing both messages.

 

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[Chris]

The issue has been identified. I called DC Power Engineering. they immediately knew what was causing the message. Nations Auto Electric said that is a first for them.

 

So on to the issue. the alternator has 2 wires coming from the regulator. The trucks like mine have a 3rd. This third wire on the right side of the plug is what is throwing the message "SERVICE BRAKE BOOSTER". That wire somehow ties into the SBA motor. The new alternator uses a Corvette regulator.

 

The truck's plug. Shown here there is a wire on the far right side.

 

The new alternator harness. Black plugs into the alternator, grey into the trucks plug. Notice on both there is no far right wire