1990 c3500 transmission question

[7beast]

Hey fellas I have a 1990 c3500 rollback truck and my question is: does my truck come equipped with a th400? Or which transmission? I got it with the original drivetrain sitting on the ground and it looks like a th400 but I don't see the section where the speedo cable would enter.. someone please help

[Accelo]

It shouldn't be a 4L80 as Production was from 1991 to 2013.
The THM 400 has a square governor cover on the side and a vacuum modular.
The 4L80 has a large plugin as it is shifted by a computer.
The 4L80 is also longer and is the top one in the picture.
There were lots of variations in the tail shaft between years.
If it's a 4x4 the speedo is on the transfer case and there isn't a tail shaft.
Cheers.

[Just call me Sean]

It doesn't have a cable, the speedometer is electric. You would have to post a picture of the transmission for us to identify it.

[7beast]

Ok I see, and yes there is a connector plug on the driver's side tail shaft it's 2wd.. anyone know what the wire colors would be? The wires were ripped out of the plug and it's kinda hard to tell on the harness of the truck .. 🤔

[ChevyTech]

Originally Posted by 7beast

Ok I see, and yes there is a connector plug on the driver's side tail shaft it's 2wd.. anyone know what the wire colors would be? The wires were ripped out of the plug and it's kinda hard to tell on the harness of the truck .. ��

The 1990 wiring service manual shows in section A on page 66 & page 67:
With RWAL the Vehicle Speed Sensor wire colors are Green/black and Purple/white
Without RWAL (Rear Wheel Antilock) it shows a three wire sensor with Pink/Black, Black/White, and Brown

[7beast]

Originally Posted by ChevyTech

The 1990 wiring service manual shows in section A on page 66 & page 67:
With RWAL the Vehicle Speed Sensor wire colors are Green/black and Purple/white
Without RWAL (Rear Wheel Antilock) it shows a three wire sensor with Pink/Black, Black/White, and Brown

Ok awesome! Good info thanks alot for your input sir. And yea my truck has a 2 wire connector so i guess that means it's not equipped with RWAL.. By any chance can u or anyone please tell me which color wire goes to the pcm and which one goes to the DRAC module? Or cluster whichever one it goes to..

[Just call me Sean]

That means it does have RWAL.

[7beast]

Originally Posted by Just call me Sean

That means it does have RWAL.

Oh darn your right I totally read that wrong thanks for pointing that out.. any clue on which wire goes to what?

[ChevyTech]

Originally Posted by 7beast

Ok awesome! Good info thanks alot for your input sir. And yea my truck has a 2 wire connector so i guess that means it's not equipped with RWAL.. By any chance can u or anyone please tell me which color wire goes to the pcm and which one goes to the DRAC module? Or cluster whichever one it goes to..

You're welcome!

As Just call me Sean said, that means it does have RWAL.

Both the VSS wire go to the DRAC module. On the way to the DRAC they go through a 10 wire connector which has 2 rows of 5 wires, which is in the area of the ECM .

[7beast]

Originally Posted by ChevyTech

You're welcome!

As Just call me Sean said, that means it does have RWAL.

Both the VSS wire go to the DRAC module. On the way to the DRAC they go through a 10 wire connector which has 2 rows of 5 wires, which is in the area of the ECM .

Cool, im gonna have to get down there and figure out which wire is what under the truck. The wiring looks like it was torn off at the transmission for some odd reason. The vss plug is connected to the vss sensor but the wires have been ripped out..