Author Topic: 4l80e standalone computer help  (Read 4994 times)

Offline Irish_Alley

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4l80e standalone computer help
« on: June 10, 2015, 07:12:43 PM »
what i want to know if i can just simply swap wire harnesses from the 84 k30 to the 91 v3500. the 84 was set up for the cummins and the 91 had a 350/4l80e. i know the transmission was part of the fuse block connection but i have a stand alone computer for that. so all i need is wiring harness to the engine from the 84 to work in the 91. it should fit no problem i just cant find a diagram for the 84. i think im going to have to physically inspect each wire to make sure theyre the same but im not near the truck or wires now so im just putting it out there
heres the 91

Edit now i need to figure out how to wire up the 4l80e tcu from a 1991 k3500 with a 6.2
« Last Edit: June 13, 2015, 10:09:05 PM by Irish_Alley »
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Offline Irish_Alley

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Re: Re: 91 v3500 vs 84 k30 fuse block
« Reply #1 on: June 10, 2015, 07:31:18 PM »
i should add both trucks are bare bones no ac, no cruise or anything fancy
84 with a single tank
91 dual tanks
« Last Edit: June 10, 2015, 07:48:04 PM by Irish_Alley »
If you can’t tell yourself the truth, who can you tell it to?~Irish_Alley

When you have eliminated the impossible, whatever remains, however improbable, must be the truth ~Sherlock Holmes

Offline Irish_Alley

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Re: Re: 91 v3500 vs 84 k30 fuse block
« Reply #2 on: June 11, 2015, 11:25:38 AM »
well the connections are two different styles and arnt compatible. i need a diagram for both so i can make one out of the 91 plug.
If you can’t tell yourself the truth, who can you tell it to?~Irish_Alley

When you have eliminated the impossible, whatever remains, however improbable, must be the truth ~Sherlock Holmes

Offline zieg85

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Re: 91 v3500 vs 84 k30 fuse block
« Reply #3 on: June 11, 2015, 11:29:21 AM »
Underdash harness for a 91 Suburban do you?  I remember taking it out, if I still have it, consider it yours if you need it.
Carl 
1985 C20 Scottsdale 7.4L 4 speed 3.21
1986 C10 under construction
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Offline Irish_Alley

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Re: Re: 91 v3500 vs 84 k30 fuse block
« Reply #4 on: June 11, 2015, 02:55:26 PM »
no, but i appreciate it. im going to have too wire the 91 fuse block to match the wires on the 84. i know some wires were removed on the 84 think i only counted 12 in the 84 vs 17 on the 91. the wires on the 84 are basic i.e. temp sensor, fuel solenoid kill switch (ignition 12v), starter wires, alternator wires and maybe something else im missing. i know there was a wire running under the cab maybe fuel sending unit wire. it shouldnt be too hard just need to see what wires correspond on the 91 to the 84 block.
If you can’t tell yourself the truth, who can you tell it to?~Irish_Alley

When you have eliminated the impossible, whatever remains, however improbable, must be the truth ~Sherlock Holmes

Offline Irish_Alley

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Re: 4l80e standalone computer help
« Reply #5 on: June 13, 2015, 10:12:24 PM »
ok think i got the wire harness figured out. from what i was told the wire colors are the same so i just need to cut and attach each wire from my 84 to the 91.

now i have to figure out which way to go with the 4l80e, i have two TCUs one from tci but its from the mid 2000s so it still has the floppy drive. so i need a pc with win xp and a floppy drive.

next i also have a tcu from a 91 k3500 6.2 4l80e. i think this will be my best bet just need to figure out how to wire it up
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When you have eliminated the impossible, whatever remains, however improbable, must be the truth ~Sherlock Holmes

Offline roboticjunky

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Re: 4l80e standalone computer help
« Reply #6 on: June 14, 2015, 02:28:59 PM »
Go to TCI and download the drivers and software. The gray box is the older TCU and the red box is the newer one. http://www.tciauto.com/tc/ez-tcu-downloads

Once you download the program. Go into the program and go to the menu bar and click Help and click Help again. Now, it will show you the TCU manual and it has the wiring set up for the 4L80E (the pins and wire colors).

Main things that need to be wired up is TPS sensor, Brake light, rpm signal, rpm ground, +12v Ign. switched power, ground, Input speed sensor, Output speed sensor, and the main plug on the transmission.
1987 V10 Silverado 350 HSR