4l80E questions - The 1947 - Present Chevrolet & GMC Truck Message Board Network

krue · 01-21-2018, 09:23 AM

I have an '03 GMC van with 6.0l and 4l80E for swap purposes. The van was a Dept. of Corrections van and they had been using it for parts. It has no gage panel so I can't tell what gear the tranny is indicating. That matters because the tranny is in limp mode (only 2nd and R) and I am trying to figure out why before I pull it. There is tranny fluid in the round connector and some sources say that could be the problem and others say not. The plug does have power to it with the key on. What should I be looking for? Replace the harness? If so where is the best source for replacement.

Bigdav160 · 01-21-2018, 09:25 AM

You need to read the trouble codes. It sounds like an electrical problem and trans fluid in the connector is a problem.

krue · 01-21-2018, 09:50 AM

Only code it shows is a temp. sensor voltage, don't remember the number off the top of my head.

krue · 01-23-2018, 03:32 AM

Anyone else?

ls1nova71 · 01-23-2018, 03:42 AM

Limp mode is 2nd and 3rd, but if you say it doesnt have power going to it when the key is on, then you need to figure that out since that's probably the problem. Check all the fuses.

krue · 01-23-2018, 07:54 AM

The plug does have power with the key on.

BR3W CITY · 01-23-2018, 01:10 PM

Quote:

Originally Posted by krue

Only code it shows is a temp. sensor voltage, don't remember the number off the top of my head.

Depends on what scanner your using. Most regular scanners will show regular DTC trouble codes (P codes). A Tech2/3 or reading via HPT Ecm scanner will show you the extended codes (T, U and BCM codes), and it will also show gears.

I'll have to check back through some of Clinebargers posts, he's the resident trans expert and has previously posted his preferred sources for trans harnesses.

krue · 01-23-2018, 08:28 PM

Quote:

Originally Posted by BR3W CITY

Depends on what scanner your using. Most regular scanners will show regular DTC trouble codes (P codes). A Tech2/3 or reading via HPT Ecm scanner will show you the extended codes (T, U and BCM codes), and it will also show gears.

I'll have to check back through some of Clinebargers posts, he's the resident trans expert and has previously posted his preferred sources for trans harnesses.

Thanks, will do.

01-21-2018, 09:23 AM	#1
krue Designated A-hole! Join Date: Mar 2003 Location: South Mississippi Posts: 36,450	4l80E questions I have an '03 GMC van with 6.0l and 4l80E for swap purposes. The van was a Dept. of Corrections van and they had been using it for parts. It has no gage panel so I can't tell what gear the tranny is indicating. That matters because the tranny is in limp mode (only 2nd and R) and I am trying to figure out why before I pull it. There is tranny fluid in the round connector and some sources say that could be the problem and others say not. The plug does have power to it with the key on. What should I be looking for? Replace the harness? If so where is the best source for replacement. __________________ "If it ain't broke, fix it 'til it is!" Being stupid ain't illegal. We're Still Debt Free Except for the House!!! www.daveramsey.com 70 GMC SWB Stepside project "Green Booger" soon to be 6.0l/4l80e 93 S-10 "Poppaw's Truck"

01-21-2018, 09:25 AM	#2
Bigdav160 Registered User Join Date: Apr 2011 Location: Klein Texas Posts: 3,852	Re: 4l80E questions You need to read the trouble codes. It sounds like an electrical problem and trans fluid in the connector is a problem. __________________ My Classics: '72 K20 Suburban + '65 Dodge Town Wagon '72 Corvette Roadster +'67 Corvette Roadster '73 Z-28 Camaro '63 Ford SWB Uni Pickup '50 Ford Coupe

01-21-2018, 09:50 AM	#3
krue Designated A-hole! Join Date: Mar 2003 Location: South Mississippi Posts: 36,450	Re: 4l80E questions Only code it shows is a temp. sensor voltage, don't remember the number off the top of my head. __________________ "If it ain't broke, fix it 'til it is!" Being stupid ain't illegal. We're Still Debt Free Except for the House!!! www.daveramsey.com 70 GMC SWB Stepside project "Green Booger" soon to be 6.0l/4l80e 93 S-10 "Poppaw's Truck"

01-23-2018, 03:32 AM	#4
krue Designated A-hole! Join Date: Mar 2003 Location: South Mississippi Posts: 36,450	Re: 4l80E questions Anyone else? __________________ "If it ain't broke, fix it 'til it is!" Being stupid ain't illegal. We're Still Debt Free Except for the House!!! www.daveramsey.com 70 GMC SWB Stepside project "Green Booger" soon to be 6.0l/4l80e 93 S-10 "Poppaw's Truck"

01-23-2018, 03:42 AM	#5
ls1nova71 Registered User Join Date: Dec 2009 Location: Independence Mo Posts: 4,117	Re: 4l80E questions Limp mode is 2nd and 3rd, but if you say it doesnt have power going to it when the key is on, then you need to figure that out since that's probably the problem. Check all the fuses. __________________ My '72 short bed build. http://www.ls1tech.com/forums/conver...6-0-4l80e.html 5.3 swap into my RUSTY '71 C10 http://ls1tech.com/forums/conversion...71-c-10-a.html

01-23-2018, 07:54 AM	#6
krue Designated A-hole! Join Date: Mar 2003 Location: South Mississippi Posts: 36,450	Re: 4l80E questions The plug does have power with the key on. __________________ "If it ain't broke, fix it 'til it is!" Being stupid ain't illegal. We're Still Debt Free Except for the House!!! www.daveramsey.com 70 GMC SWB Stepside project "Green Booger" soon to be 6.0l/4l80e 93 S-10 "Poppaw's Truck"

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