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Brake warning lights came on

Tiny
DLYNDAKER2001
  • MEMBER
  • 2005 GMC SIERRA
Brakes problem V8 Four Wheel Drive Automatic 71,000 miles

Yesterday all of my brake warning lights came on with a Service Brake System Message in my display under the speedometer. Speedometer began bobbing up and down and not reading correctly. Truck didnt wanna shift, felt like a rev limiter was engaging. The truck didnt wanna get out of its own way. If I came to a complete stop all of the messages would turn off, and the truck would act fine. Then I would drive maybe 100 ft. And everything would go off again. I have been having problems with the speedometer acting funny for a few months. It would act up then be fine again. I changed my front brake pads the day before yesterday. Everything looked fine. Took truck to mechanic yesterday after everything went crazy. He said everything looked fine with the brakes and he replaced my vehicle speed sensor on the transmission. Drove truck home last night it acted fine. Drove it about 20 miles today and it did the same thing as it did yesterday.
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Saturday, April 3rd, 2010 AT 1:18 PM

26 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,700 POSTS
Actually, the speed sensor was my first guess. However, since there are so many things happening at once, I recommend having the computer scanned to identify what is happening. Most parts stores will do it for free.

Have that done and let me know what you find.

Joe
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Saturday, April 3rd, 2010 AT 3:18 PM
Tiny
DLYNDAKER2001
  • MEMBER
  • 5 POSTS
Mechanic did a diagnostic scan. I'm assuming the speed sensor is all that came up. I picked the truck up after hours so I didnt get a chance to talk to him. Would the rev limiter kicking in be a saftey mechanism if the truck thinks you have no brakes I would assume it wouldnt wanna let you go very fast. Would the brakes warnings also be related to the speed sensor? I was wondering if the computer thinks you are breaking but the sensor isnt saying you are slowing down the computer might also read it as a brake malfunction. Also is it possible that this could be related to the GMC technical service bulletin regarding faulty speedometers? I will be speaking with my mechanic about it he is my uncle so he cant run and hide. Lol I will let you know what I find out.
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Saturday, April 3rd, 2010 AT 5:23 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,700 POSTS
Actually, they are all interconnected. I miss the good old days. Things were much easier. Mechanics today have to basically have engineering degrees.

As far as the speed sensor, it controls several things. The speedo, traction control, ABS is tied in, transmission shifting patterns.

Let me know what you find. Also, as far as a rev limiter, it wouldn't do this.

Have a good Easter and I look forward to hearing from you.

Joe
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Saturday, April 3rd, 2010 AT 11:25 PM
Tiny
DLYNDAKER2001
  • MEMBER
  • 5 POSTS
Well I took truck back to the mechanic and he accidentally changed the 4wd speed sensor. He changed them back and installed the new sensor on the vehicle speed side. He explained how the sensor controls all of your shifting, braking, and how the truck would interpret the bad sensor as a braking problem and would screw with my transmission. Anyways drove truck home and seemed fine. Started it this afternoon and all the bells and whistles started goin off again. It is a sensor problem cuz it just wont do it then everything goes crazy and it might shut off and be fine 2 seconds later. I have all the same symptoms as before. If this controls the shifting I am assuming the truck is just going in and out of nuetral and that it is not a limiter. Other then the speed sensor is there anything else that could be causing this problem. I heard there are alot of speedometer guage problems with this year of truck could that be causing the trouble. I also see that gm has a technical service bulletin out on the speedometers.
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Tuesday, April 6th, 2010 AT 12:59 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,700 POSTS
The TSB is regarding the replacement of the cluster due to a faulty speedo. That wouldn't cause all of the problems. When all the lights come on and the problems start, has a code ever been set in the computer that the mechanic told you about? In one of the earlier postings, you mentioned he scanned it, but you didn't get to ask him.
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Tuesday, April 6th, 2010 AT 10:35 PM
Tiny
DLYNDAKER2001
  • MEMBER
  • 5 POSTS
It came back as a vehicle speed sensor code. Is it possible the new sensor was junk right out of the box. Is there a way to test a sensor to find out? I spent a few hours replacing a wheel bearing hub assembly on a truck I had before this one only to get everything back together and find out the wheel speed sensor was junk on the new hub.
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Wednesday, April 7th, 2010 AT 7:35 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,700 POSTS
Yes it can be bad. Believe it or not, it isn't that uncommon. It seems like everything is coming from countries where they pay employees a dollar a week to work. As a result, you get what you pay for.
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Wednesday, April 7th, 2010 AT 9:27 AM
Tiny
DLYNDAKER2001
  • MEMBER
  • 5 POSTS
Picked up truck again tonight. Mechanic replaced sensor again. While driving it home when I came to a complete stop it takes the speedometer a sec to go all the way down to zero from ten mph. Did the same thing the other day when I picked up the truck and my troubles started again the following day. Hopefully my major troubles are over with with the new speed sensor. Any ideas about the speedometer lag? I got a feeling I havent seen the end of this yet.
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Wednesday, April 7th, 2010 AT 7:02 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,700 POSTS
The lag could be a resistance problem or the insturment panel itself. Let me know if it helped.

Joe
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Wednesday, April 7th, 2010 AT 8:54 PM
Tiny
NATHAN BEAN
  • MEMBER
  • 10 POSTS
Did you ever figure out the lag issue? I am having all the same issues you are! My speed sensor went bad, changed it and now there is a lag from 0-5 mph and stopping from 5-0 which will cause abs to engage. Any advise?
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Tuesday, October 24th, 2017 AT 7:12 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,490 POSTS
This is telling you a wheel speed sensor is weak causing the ABS think a tire is skidding. You should scan the ABS to see whats wrong or you can test the sensors manually. HEre is a video and a guide to help you get the problem fixed.

https://youtu.be/rTtAnsOlZU4

and

https://www.2carpros.com/articles/abs-wheel-speed-sensor-test

Please run some tests and get back to us so we can keep helping you.

Cheers, Ken
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Wednesday, October 25th, 2017 AT 7:20 PM
Tiny
NATHAN BEAN
  • MEMBER
  • 10 POSTS
I’ve already scanned it, there are no ABS codes nor are there any codes on the PCM. My speed vehicle sensor did go out, it started jumping around, doing crazy stuff. Replaced the sensor in the transfer case, now the speedo is just delayed. When the Speedo is sticking that’s when abs is kicking it. The wheel speed sensors shouldn’t have anything to do with the speedo, would it? Abs is doing it’s job, however the PCM still thinks the truck is moving due to the delay/hang. I’ll post a video shortly.
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Wednesday, October 25th, 2017 AT 9:39 PM
Tiny
NATHAN BEAN
  • MEMBER
  • 10 POSTS
Kind of hard to tell but you you hear abs kick in, the truck is already at a stop. There is also a delay when taking off. I’ve verified this isn’t a problem in the cluster using my code readers live data to view the vehicle speed sensor. There is a delay, just can’t figure where its coming from. Another thing to mention, during the rescues of hurricane Harvey I got about 4 inches of water in the cab of the truck, never had any issues (electrical or mechanical) until now. This all started shortly after changing my transfer case fluid a couple weeks ago, which was quite milkey.
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Wednesday, October 25th, 2017 AT 9:47 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,490 POSTS
Water can make all kinds of weird problems. I would remove the carpet and most of the interior and unplug all controllers BCM/ABS because it sounds like you have moisture in the connectors. Thanks for the video really helps. The CAN depends on a clear stream of data and moisture interrupts it.

Please let us know what you find.

Cheers, Ken
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Friday, October 27th, 2017 AT 11:02 AM
Tiny
NATHAN BEAN
  • MEMBER
  • 10 POSTS
Will do! I’ll let y’all know what happens, thanks!
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Friday, October 27th, 2017 AT 11:09 AM
Tiny
NATHAN BEAN
  • MEMBER
  • 10 POSTS
What/how does the pickup work in the transfer case for the speed sensor? Could something have gotten damaged from water being in the fluid? It wasn’t good coming out.
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Friday, October 27th, 2017 AT 1:26 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,490 POSTS
The sensor connections get damaged by the water is more likely the issue. Can you remove the connector and check it out. I don't think water in the fluid will hurt it.

Cheers, Ken
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Saturday, October 28th, 2017 AT 4:09 PM
Tiny
NATHAN BEAN
  • MEMBER
  • 10 POSTS
Here is a video
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Saturday, October 28th, 2017 AT 7:21 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,490 POSTS
O that is goopy for sure. Thanks for the video. Can you check the connections for corrosion please.
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Monday, October 30th, 2017 AT 10:50 AM
Tiny
NATHAN BEAN
  • MEMBER
  • 10 POSTS
Connection looks fine. Checked all the plugs under the carpet and all seem dry.
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Monday, October 30th, 2017 AT 12:10 PM

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