Help us help you. By posting the year, make, model and engine near the beginning of your help request, followed by the symptoms (no start, high idle, misfire etc.) Along with any prevalent Diagnostic Trouble Codes, aka DTCs, other forum members will be able to help you get to a solution more quickly and easily!
2003 Silverado 1500 Ext cab 4.8L V8. One day the "Service Brake Booster" message came on. I put scan tool and no error codes. I ask couple of mechanics they said I needed to replace Brake Booster, so I did. Message still came on. I replaced the Supplemental Brake Assist (SBA) and vacuum and still message came on. My Battery was 4 years old, so I replaced it. I also replaced the Alternator and message still come on. I checked visually. for loose wires hardnesses and they ok. I went and did the 5 time start procedure and it worked however when I started the truck again the message reappeared. If I push the cluster odometer the message go's away but come back on upon restart. I purchased diagrams from GM website, Mitchell website to follow connections. I also went on YouTube for videos and found that other 2003 truck owners had same problem and could not figure it out, so they just got rid of the SBA and by passed the harness wiring by putting a small wire from the SBA signal sending (Dk Blue) to the Ground wire. To me that is not solving it. I want to learn how to troubleshoot open/short circuit. I have been studying your videos and wiring diagrams. Have you come across this problem? Can you give me some suggestions how to trace the wires.
" If I push the cluster odometer the message go's away but come back on upon restart. "
Check the connector on the back of the IPC for loose or spread open terminals. Do a pin drag test. If all seems good in the connector it could be a connection in the IPC.
