need help no Cruise control, Abs and Parking brake lights on

jham

Original poster
Member
Nov 20, 2011
1,334
Today I did my 14 bolt swap everything went fine shortened the driveshaft 2 inches test drove it everything good then i start to head to my girls house about 5 miles later I go to set the cruize and it wont work i am like wtf then a couple miles later the ABS and parking brake light come on I pull over to check nothing is hot in the brakes fluid is good in the master cylinder. I turn the truck off and drive for about 5 miles then the lights come back on I have a 2005 Trailblazer so there is no traction control i didn't touch any Wiring on the truck so i am at a loss any help will be appreated
 

The_Roadie

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Nov 19, 2011
9,957
Portland, OR
Didn't touch any wiring, but the jostling sounds like something got intermittent. Typically the ABS ground will cause what you're seeing. Clean up this connection under the dash and the other to the frame and see if it gets better.

Converted_file_d03c47d4.jpg


3249d1327805116-02-trailblazer-wont-start-1.jpg
 

RayVoy

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Nov 20, 2011
939
Somewhere around '05 the trucks went from a 3 channel (2 front, 1 rear) ABS to a 4 channel (2 up and 2 back). You didn't end up with a mis-match by any chance?
 

jham

Original poster
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Nov 20, 2011
1,334
i cleaned the two gorunds went for another drive still no cruize and the lights came on after 3 miles. I wonder if the gear change is messing up the speed sensor on the output of the trans?
My old diff had no eletric plugs on it at all. all my brakes are working as they should when I first start the truck.
 

jham

Original poster
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Nov 20, 2011
1,334
RayVoy said:
Somewhere around '05 the trucks went from a 3 channel (2 front, 1 rear) ABS to a 4 channel (2 up and 2 back). You didn't end up with a mis-match by any chance?

any chance you might know where the 1 or 2 in the rear might be. i know the 14 bolt has 2 speed sensors on it
 

The_Roadie

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Nov 19, 2011
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If there's only one in the older trucks, it's on the tailpiece of the tranny or transfer case. If there's two in the back they're near the brake rotors IIRC. AlekG wrote it all up in his axle upgrade thread on ORTB.

Edit: What gear change?
 

jham

Original poster
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Nov 20, 2011
1,334
the roadie said:
If there's only one in the older trucks, it's on the tailpiece of the tranny or transfer case. If there's two in the back they're near the brake rotors IIRC. AlekG wrote it all up in his axle upgrade thread on ORTB.

Edit: What gear change?

going from the 8 inch with 3.42 to the 14 bolt from a ss with 4.10. mine only has the sensor on the tail section of the tranny
 

The_Roadie

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Nov 19, 2011
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Ahhh, so your front wheels are putting out more pulses per mile than they used to for the same driveshaft RPM. I bet you need to edit the gear ratio that's baked into your PCM. A good question for PCMforless.
 

jham

Original poster
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Nov 20, 2011
1,334
the roadie said:
Ahhh, so your front wheels are putting out more pulses per mile than they used to for the same driveshaft RPM. I bet you need to edit the gear ratio that's baked into your PCM. A good question for PCMforless.

I hope I am not SOL then since i know on the 02 to 05's you cant adjust the pcm for tire size why does this always happen to me when places are closed
 

jham

Original poster
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Nov 20, 2011
1,334
the roadie said:
GM must have been able to adjust the gear ratio or else they would never sold 4.10 gears in 02-05, and I know they had that option.

that is true Thanks Roadie I will be calling pcm for less on monday morning then
 

RayVoy

Member
Nov 20, 2011
939
Hmmm, so the speedo is off as well; the rear sensor, as roadie said, monitors the rotation speed of the driveshaft.
The vehicle road speed is also determined by the speed of the rear driveshaft.

I think simply programming the new axle gear ratio into the PCM (and tire size if no longer stock) will fix the problem.


Hmmm. guess I shouldn't have gone for a rum and ginger while I was typing, you guys have got it fixed :rotfl:
 

jham

Original poster
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Nov 20, 2011
1,334
RayVoy said:
Hmmm, so the speedo is off as well; the rear sensor, as roadie said, monitors the rotation speed of the driveshaft.
The vehicle road speed is also determined by the speed of the rear driveshaft.

I think simply programming the new axle gear ratio into the PCM (and tire size if no longer stock) will fix the problem.

yes the speedo is off it reads 50 when i was going 55 before the swap now it reads 58 when going 55 i have 33.5 inch tires
 

jham

Original poster
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Nov 20, 2011
1,334
Well I contacted pcmforless and there's no way to to change the gear ratio in the pcm that sucks I am really confused on there site it say the can work with any modifications done
 

jham

Original poster
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Nov 20, 2011
1,334
RayVoy said:
It seems incredulous to me, that the PCM can not be corrected for a ratio change; but, take a look at this (page 9)

http://www.superlift.com/instructions/33003.pdf

seems that way to me also I know a local gm tech that's checking on changing the pcm for the ratio something about a calling in to gm to get something from them. So I shall see tomorrow thanks I will really check into the link you found
 

MAY03LT

Member
Nov 18, 2011
3,422
Delmarva
jham said:
Well I contacted pcmforless and there's no way to to change the gear ratio in the pcm that sucks I am really confused on there site it say the can work with any modifications done

I'm not an expert on pcm reprogramming by any means but I recall reading that RPO changes can be made by a dealer (who knows their stuff) or someone with a tech2/TIS access. So, if it is possible, the GU6 code would get changed to GT5.
 

jham

Original poster
Member
Nov 20, 2011
1,334
MAY03LT said:
I'm not an expert on pcm reprogramming by any means but I recall reading that RPO changes can be made by a dealer (who knows their stuff) or someone with a tech2/TIS access. So, if it is possible, the GU6 code would get changed to GT5.

yes that's it and the reprogram has to come from gm and gonna run me 80$ which is more than worth it so I don't hear the damn beeping for 30 seconds ever time I drive it
 

jham

Original poster
Member
Nov 20, 2011
1,334
Well here what I have figured out so far my abs and parking brake lights are staying off now was able to reprogram the pcm for 265 tires which made my Speedo closer to being on off by 3 mph at 55 now I couldn't get the gear change from gm for some reason though
I have a intermittin issue with my cruise still all the functions work in the multifunction switch which is looking like it might be a ignition switch gonna swap one out this weekend to see if it fixes it.
 

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