4l80e in Limp mode?
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Teching In
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4l80e in Limp mode? I purchased an '03 GMC Savana 3500 from auction for the 6.0l/4l80e to swap into a '70 GMC. Vehicle had no driveshaft so I couldn't test drive. Fixed that and find the only gears I have are 2nd and reverse, which research says is "LIMP" mode. I have power to the transmission, but I also have fluid in the main connector to the transmission. Fluid looks great, very clean and my cheap scanner picks up no tranny related codes. I would love to see this thing shift out once before pulling for the swap. TIA for any help.
Last edited by krue; Dec 24, 2017 at 10:50 AM. Reason: Add info
TECH Fanatic
Joined: Jan 2015
Posts: 1,114
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From: Fort Worth, Texas
Does your scanner show shift solenoid state data?
Check the Fluid Pressure Switch states as well, If the PCM thinks it's in manual 2nd.....The truck will take off in 2nd.
Attachment 718161
Check the Fluid Pressure Switch states as well, If the PCM thinks it's in manual 2nd.....The truck will take off in 2nd.
Attachment 718161
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Thread Starter
Teching In
Joined: Jun 2017
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Teching In
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I purchased an '03 GMC Savana 3500 from auction for the 6.0l/4l80e to swap into a '70 GMC. Vehicle had no driveshaft so I couldn't test drive. Fixed that and find the only gears I have are 2nd and reverse, which research says is "LIMP" mode. I have power to the transmission, but I also have fluid in the main connector to the transmission. Fluid looks great, very clean and my cheap scanner picks up no tranny related codes. I would love to see this thing shift out once before pulling for the swap. TIA for any help.
If you have fluid in the connector that will make it go into limp mode. Put a new harness in the trans. Isn’t hard to do just pull the pan.
Thread Starter
Teching In
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Teching In
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I got mine at Whatever it Takes transmission supply but they are on eBay also. Just look up 4l80 harness. Might have to know what year trans you have. If the cooler lines are side by side I think that’s a old model. If ones a few inches behind the other think it’s a new model. Like 2004 up
Thread Starter
Teching In
Joined: Jun 2017
Posts: 7
Likes: 0
I got mine at Whatever it Takes transmission supply but they are on eBay also. Just look up 4l80 harness. Might have to know what year trans you have. If the cooler lines are side by side I think that’s a old model. If ones a few inches behind the other think it’s a new model. Like 2004 up