service brake system

cashflow50 · September 6, 2013

2003 GMC yukon 4.8L V8

As I drove home yesterday, I heard 3 chimes and 3 icons iluminated on the dashboard (see photo)

the left most photo says ABS the one next to is BRAKE and the one on the top right is Traction Control. The vehicle stalled for a second and drove normally for about a mile, then the same thing happened...stalled for a second and then normal. I've noticed that when I press on the brake pedal, the brake is not that strong...I'll have to pump the brake pedal to stop. What could be wrong. Need help. thanks. On the same token...I remember about 2 or 3 years ago when I took my vehicle in for service, the tech said that the master cylinder needs to be changed, because it had a leak. So naive I forgot about this and drove it for 3 more years. Do you think its the master cylinder thats causing this?

txab · September 6, 2013

You need to have the codes read. You probably have an ABS code present

cashflow50 · September 9, 2013

thx txcab for the response..Trying to avoid costly expenses taking it to the dealer, I contacted my personal mechanic who is a master tech for Mercedez Benz here. He did the routine turn the vehicle on and observed the illuminated dash icons and pressed on the brake pedals. Bluntly he said my master cylinder is bad with a leak and also checked if the fluid was contaminated. He told me to go to a nearby autoparts store and get a new master cylinder for my yukie. Question is...does the car stalling like the above description tied with the bad master cylinder?

MikeNH · September 9, 2013

Stalling can be from a vacuum leak, which could be caused by a bad brake booster, not the M/C though unless its one unit.

cashflow50 · September 12, 2013

Stalling can be from a vacuum leak, which could be caused by a bad brake booster, not the M/C though unless its one unit.

where would the most common vacuum leak be located? the mech sprayed all over the head area and no change in idle.

gmtech4 · September 13, 2013

clean maf sensor for a low idle concern

cashflow50 · September 23, 2013

ok guys..My mechanic replaced the brake master cylinder and starter. The next day I started my vehicle and it started with no problems. I drove for about a mile or so and my vehicle did the same thing as mentioned on the my first post (see above). This time though while in drive, the engine cutoff right before i was pulling in to a parking lot. I tried starting the vehicle and it just kept on cranking. I cranked and cranked until I got it to start, then I parked the car in a stall. WTF is happening? Could it be ABS related, because it all started with the 'DIC' saying "service brake system"? Does the ABS system have a sensor or a controller that shuts the engine down? I got too many questions floating around in my head that could be the problem.

I called my mechanic up and he came to check out the situation again. He said it might be an ignition problem. He then looked and looked for clues under the steering column. He then tried to start the vehicle and it cranked, but only for a second or two. He said that the power just shuts off while turning the key. Is it an electrical problem? Experts please help. Thanks in advance.

del

cashflow50 · September 23, 2013

You need to have the codes read. You probably have an ABS code present

the funny thing is my mechanic tried to pull the code, but the scanner did not spit out any, because the check engine light didn't come on.

cashflow50 · September 25, 2013

Does the ABS "if it has problems" cut the engine off or make it not start? All these issues started when the "service brake system" along with the ABS, brake and Traction Controls lights came on. Bad brake assist? Need help on this guys. Thanks

cashflow50 · September 25, 2013

i've read in other forums that the TPS, TAC or the TB maybe the cause of the infamous "Reduce Engine Power". Engine starts right up but stalls. It also could be the pigtail connector to the harness that attaches to the TB. I'll focus my efforts in that area first and go from there onto the grounds in the whole engine bay. If anyone has any ideas..please chime in.

cashflow50 · September 26, 2013

First of all I managed to start up the truck...Had a hard time but it fired up crank after crank. I let it idle for about 10 minutes and at the same time went to start jiggling all the wires in the bay, especially the TPS harness. No sputtering or difference in idle. I turned off the engine. I then inspected the TPS harness plug. The wires looked ok, but noticed a couple of the wires were bent and kind of kinked. So I un wound the wires and made them straight instead of factory twined. I started the vehicle and it fired right up immediately. I tried it several times and same result and immediate start up. No long cranking.

(I can say now that it fires up when engine is warmed up to normal temp)

Then I let it cool down just to test if it fires back up when at cold crank. 3 hours later, I tried firing her back up again. The engine was hard to fire up. I had to crank and crank until it barely fires up with me pressing the pedal trying to rev the engine to get it to turn over. WTF. So now I know that at cold start it engine barely could crank, although when the engine is warm at normal temp, I could get it to start at one click.

What could be wrong guys. Need your input.

del

txab · September 26, 2013

Have you checked fuel pressure?

cashflow50 · September 27, 2013

yes i did .. fuel pump was installed at the dealership for 1G. its still good acccording to the mech. fuel filter is still original piece. would that spit out those cluster messages and cause the no start?