Help identifying TV cable

[L31MaxExpress]

Good to know. The trans doesn’t seem to be hurting but I was worried it would get chewed up by not downshifting at WOT

I would replace the vacuum hose ends on both ends of the metal tube where it attaches to the intake and modulator. They get soft with age and will cause the modulator to become sluggish to vacuum changes which can hurt the trans.

 

[mwilliams55555]

Looking for some guidance. I have a 1988 c1500 305 auto. I finished some upgrades to the TBI (new injectors and a spacer). I took it for a test drive and can notice some gains, but when I floor it the trans doesn’t downshift into a passing gear. I figured I needed to adjust the TV cable and popped the hood and I don’t see a TV cable. I have two cables coming off of the TBI, the throttle cable and another cable below it that goes to a plastic box on the firewall. Inside that box is a circuit board and a spring tensioned spool. I’m guessing this is the TV cable for that model year, but I do not see anyway to adjust it. When I pull the throttle open, slack on that ribbon doesn’t get taken up by the spool. Anyone else confused?

Easy way to tell difference between the 700r4/4L60 and the 3L80/400, count the bolts on the pan, 16 bolts and looks like a cake pan it's a 700/4l60 type, 17 bolts and looks like it was dropped on 2 golf balls, indentation in bottom of the pan, it's the 400/ 3L80, also it's not a rectangle like the 700/4L60.

 

[Schurkey]

Perhaps a moderator will move this thread to "Transmissions".

^^^ Still valid.

Well, at one time that truck had cruise control.

Yup.

If your column only has D 2 1 you do not have the 700R4, probably TH350 (3L60) since it's a 1500. The square hole on the plate under the throttle cable is where the TV cable would go, if you had a 700R4.

A 350 would have a kickdown cable, probably in the same place as a 700/4L60 would have a TV cable.

Look for a vacuum line going to the trans for your kick down.

Yup--sort of. The vacuum hose would go to the vacuum modulator, not a "kick down". But the vacuum modulator can affect kickdown, indirectly.

There is a vacuum line from the side of the trans to the intake manifold behind the TB.

Easy way to tell difference between the 700r4/4L60 and the 3L80/400, count the bolts on the pan, 16 bolts and looks like a cake pan it's a 700/4l60 type, 17 bolts and looks like it was dropped on 2 golf balls, indentation in bottom of the pan, it's the 400/ 3L80, also it's not a rectangle like the 700/4L60.

He's said that there's a vacuum hose to the side of the trans.

Cannot be a 700 or 4L60, as they don't use vacuum modulators at all. (Significant design screw-up, in my opinion. Better to have a vacuum modulator for 95% of applications, and replace it on the 5% of supercharged vehicles with some sort of mechanical/cable TV arrangement, than to screw-up 95% of your applications with a TV cable.)

Cannot be a swapped-in TH350, as the vacuum modulator is at the rear, AND they'd use a kickdown cable.

Therefore, has to be a TH400-family three-speed auto transmission. They're the only ones with a vacuum modulator on the side of the trans.

 

[mwilliams55555]

^^^ Still valid.


Yup.


A 350 would have a kickdown cable, probably in the same place as a 700/4L60 would have a TV cable.


Yup--sort of. The vacuum hose would go to the vacuum modulator, not a "kick down". But the vacuum modulator can affect kickdown, indirectly.




He's said that there's a vacuum hose to the side of the trans.

Cannot be a 700 or 4L60, as they don't use vacuum modulators at all. (Significant design screw-up, in my opinion. Better to have a vacuum modulator for 95% of applications, and replace it on the 5% of supercharged vehicles with some sort of mechanical/cable TV arrangement, than to screw-up 95% of your applications with a TV cable.)

Cannot be a swapped-in TH350, as the vacuum modulator is at the rear, AND they'd use a kickdown cable.

Therefore, has to be a TH400-family three-speed auto transmission. They're the only ones with a vacuum modulator on the side of the trans.

I read that it was on the back of the tranny after I said it, 350 pan is a small square with a corner cut off, forget how many bolts on pan, been a long time since I had one come through the shop