6L80 Shifting Questions
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Teching In
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6L80 Shifting Questions I finally have my C10 swap running, but I have a question for all you 6L80 users out there:
How does your linkage work? I used a Shiftworks column shifter linkage for the 4L80 that supposedly works for the 6L80, but as of right now, all I'm getting is Park and Drive. There's no Reverse and no Neutral. I know the trans is good, as it worked when it came out of my G8. I understand the selector arm is programmable, would it be something my tuner needs to check out?
How does your linkage work? I used a Shiftworks column shifter linkage for the 4L80 that supposedly works for the 6L80, but as of right now, all I'm getting is Park and Drive. There's no Reverse and no Neutral. I know the trans is good, as it worked when it came out of my G8. I understand the selector arm is programmable, would it be something my tuner needs to check out?
TECH Junkie
Joined: Dec 2005
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You should be able to "feel" the notches in the transmission. Park, Reverse, Neutral, Drive and Sport Mode. Actually I think there are two more but not used.
If you have the notches it could be the transmission controller does not match the E38ecm software wise. They should both be of the same year or close for starters.
If you have the notches it could be the transmission controller does not match the E38ecm software wise. They should both be of the same year or close for starters.
TECH Resident
Joined: Feb 2014
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From: Encinitas CA
Yes. You should feel the notches for each. can you find reverse and neutral if you just shift the trans selector without the linkage? I'd start there. If not, you have another problem.
Just use the lever on the side of the trans and count the detents from park.
If I click several past Drive, eventually I get to one which narrows to 1st and 2nd.
Doug
Just use the lever on the side of the trans and count the detents from park.
If I click several past Drive, eventually I get to one which narrows to 1st and 2nd.
Doug
Thread Starter
Teching In
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6L80 Shifting Questions no codes. that might explain why efilive is only showing it in 3rd gear.
I'm thinking it might be that the TCM is expecting a BCM, which the truck doesn't have. Can that be tuned out, or should it have been done via a resistor in the wiring harness?
I'm thinking it might be that the TCM is expecting a BCM, which the truck doesn't have. Can that be tuned out, or should it have been done via a resistor in the wiring harness?
Last edited by Ikarus; May 8, 2015 at 12:46 AM.
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TECH Junkie
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In my case the GMLAN wires go to the ALDL plug from the transmission. At that point I have a 120 ohm resistor across the two wires to signal the end of the line so to speak. If one had a BLM they would go to that.
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Teching In
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6L80 Shifting Questions Well, I'm not sure which two wires are the right ones, but one pair does have 120 ohms of resistance, which I'm assuming is correct to "terminate" the BCM signal. It still only runs in limp mode. And still no codes. Pat went through and deleted anything unnecessary that was trying to pull from the BCM.
Launching!
Joined: Feb 2011
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From: Raleigh NC
Well if its 120 ohms, then that is a problem. Needs to read 60. Should be pins 6 and 14. Add a 120 ohm resistor across the back of the two pins and then you should read 60 ohms and the ECM and TCM can now communicate. Someone correct me if I'm wrong.
I have a BCM with my ECM and TCM so I didn't need the resistor on my setup and it reads 60 ohms at the DLC plug
I have a BCM with my ECM and TCM so I didn't need the resistor on my setup and it reads 60 ohms at the DLC plug
Thread Starter
Teching In
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Well if its 120 ohms, then that is a problem. Needs to read 60. Should be pins 6 and 14. Add a 120 ohm resistor across the back of the two pins and then you should read 60 ohms and the ECM and TCM can now communicate. Someone correct me if I'm wrong.
I have a BCM with my ECM and TCM so I didn't need the resistor on my setup and it reads 60 ohms at the DLC plug
I have a BCM with my ECM and TCM so I didn't need the resistor on my setup and it reads 60 ohms at the DLC plug
I'll let you know how it turns out.
Thread Starter
Teching In
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6L80 Shifting Questions Putting the resistor in line dropped resistance between 6 and 14 to 60 ohms. Trans was still in limp mode, but I didn't disconnect the battery and let it sit for a while, either.