GM Tech help

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winterhoff
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GM Tech help

Post by winterhoff » Fri Sep 07, 2018 2:19 pm

I have a 2003 Chevy Z71 Tahoe the rear transfer case had a pin hole in it so i replaced it with a after market one got it all together and it will not shift right and the ABS light will not go off . The sensors in the case seem to check ok and the fuses are ok and the four wheel drive seems to work ok . It's bugging the heck out of me . Any help would be greatly appreciated
Thanks Ron

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Re: GM Tech help

Post by Keith Morganstein » Fri Sep 07, 2018 6:29 pm

winterhoff wrote:
Fri Sep 07, 2018 2:19 pm
I have a 2003 Chevy Z71 Tahoe the rear transfer case had a pin hole in it so i replaced it with a after market one got it all together and it will not shift right and the ABS light will not go off . The sensors in the case seem to check ok and the fuses are ok and the four wheel drive seems to work ok . It's bugging the heck out of me . Any help would be greatly appreciated
Thanks Ron
Do you have access to a Snap-on or other high end scan tool that will show real time speed of all the sensors?

I had a similar problem with an all wheel drive chevy after replacing the transmission. I think there were five codes, all seeming serious, and transmission, transfer case related. A drive with with the scan tool revealed a bad wheel speed sensor. (Incidental to the job) repairing the sensor wire solved all the issues and codes.

There are some Master GM techs on this board. One is woody b, But they have to see this thread

Link where woody b gives advice, you might want to PM him.
viewtopic.php?f=19&t=51909&p=708579&hil ... on#p708579
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woody b
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Re: GM Tech help

Post by woody b » Sat Sep 08, 2018 11:27 am

You need to get a scanner and at least see what codes you have. Does the speedometer work? It's been a while since I worked on a 2003. Is there 2 sensors on the rear part of the transfer case or just 1? Some of the 4wd's have an inline connector to extend the output shaft harness back to the transfer case. Look in the harness on top of the transmission near the end of the transmission/front of the transfer case. On some models there's an inline connector taped up. I've had problems with broken wires there. I just remove the inline connector and extend the harness. I'm pretty sure a 2003 doesn't have rear wheel speed sensors (for abs) but instead use the signal from the output shaft sensor. A problem with a front wheel speed sensor wouldn't affect how the transmission shifts.
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Re: GM Tech help

Post by winterhoff » Sun Sep 09, 2018 9:24 am

Thanks for responding ...Yes it has 2 sensors on the back half replaced case and no the speedometer does not work
Thanks Again Ron

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Re: GM Tech help

Post by woody b » Sun Sep 09, 2018 10:31 am

It may be a bad sensor but I suspect a wiring problem. Look closely at the wires near the connectors, and check for the inline connector I described earlier.
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Re: GM Tech help

Post by winterhoff » Mon Sep 10, 2018 7:58 am

Thanks Woody

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Re: GM Tech help

Post by E.R. Racing » Mon Sep 10, 2018 8:25 am

Do you have the two speed sensor connectors swapped?

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Re: GM Tech help

Post by winterhoff » Mon Sep 10, 2018 12:35 pm

We just got under it checked the sensors with a ohms meter and they checked 1445 ohms also checked the connectors and they check ok there is a 3rd connector above that the other 2 connect to above but it's real hard to get to . Will have to find a shop to get it on a rack to get to it. The guy that changed the case last week said when he test drove it ABS light will not go out and the speedo will not work he checked to make sure the connectors where on right we also did that today . have not test drove it but put it in gear on the jack stands now the speedo works but the abs is still on . Is there any kind of a reset for the abs ??
Thanks guys for the help
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Re: GM Tech help

Post by woody b » Mon Sep 10, 2018 1:41 pm

If everything works correctly the ABS light will go off after it's driven a little.
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Re: GM Tech help

Post by winterhoff » Mon Sep 10, 2018 3:16 pm

Thanks Woody
I put it on the ground went for a test drive seems to shift ok but when you just about come to a complete stop i hear a growling noise that sounds like the abs is doing something and you can feel it in the brake pedal like it is getting ready to pulsate
thanks again for the help
Ron

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Re: GM Tech help

Post by woody b » Tue Sep 11, 2018 10:04 am

You need to get a scanner and graph the wheel speed sensors. One of them is reading slightly slow, but not slow enough to set a code. The front sensors are problematic on that year.
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Re: GM Tech help

Post by woody b » Tue Sep 11, 2018 11:57 am

I need to add, until you get the low speed abs activation diagnosed and repaired do something to disable the ABS. Either remove the abs fuse or just reach into one of the front wheel wells and disconnect one of the front wheel speed sensors. I saw a guy crash into a car in a parking lot due to ~3mph abs activation.
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Re: GM Tech help

Post by winterhoff » Tue Sep 11, 2018 4:35 pm

Woody Thanks for all the help

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