GM TV cable adjustment


Do it or die!

This TV cable adjustment is not a hard one but… and this is a big BUT, If you don’t do it or muck it up you will kill your trans in real short order!

Function of the TV Cable: Many people believe that this is a detent downshift cable and that this is the only function that the cable performs. In actuality, the TV Cable controls line pressures, shift points, part throttle downshifts and detent downshifts. The cable functions similarly to the combination vacuum modulator/cable systems found on other automatic transmissions.

Many GM vehicles are equipped with  automatic transmissions that use this TV cable. This is short for Throttle Valve cable which controls the shift characteristics of the transmission. This cable connects the transmission with the carburetor or fuel injection throttle body linkage. It is critical that you properly adjust the TV cable any time the transmission or any other parts, carb, intake have been disturbed for any reason. There is some geometry involved that needs to rock solid and dead on. The adjustment is a quick fix, and no tools are required.

Before we get to the adjustment here are some critical notes.

TV Cable setup

If you are retrofitting your  700R4/2004R transmission in place of a different model transmission (i.e. TH-350 or TH-400) you need the right cable and bracket combo. you need a cable designed for the 700R4/2004R transmission. The TH-350 and older TH-200 cables are designed differently and will not work. A salvage yard cable may work but be forewarned: There are about 30 different length cables found on stock vehicles and a cable that is too short in your application will not work. Also, used cables could have a number of problems as well, including stretched cables, damaged sheathing or housings or mutilated cable ends.

If this is a trans  conversion or update you need a bracket that will allow the TV Cable to mount to the carburetor/throttle body. TCI® carries two brackets: TCI® 376700 works with Rochester Quadrajets, Carter AFBs or Edelbrock Performer carburetors. TCI® 376800 works with most Holley carburetors. If you are using a Chevrolet TBI/TPI induction system, then correct brackets can be obtained from a salvage yard or a local car dealership.

First, Locate the TV cable that goes to the engine. Usually it is just below the throttle cable itself. If you follow this cable back a bit you will find the mount bracket and immediately on the other side of this bracket will be a quick release tab. Refer to the service manual for a diagram if you are unsure of its location.

Next, Press the adjustment tab on the slider and hold it while pushing the cable into the slider as far as it will go. Release the tab.

Now, Get in the vehicle and press the accelerator as far as it will go. The TV cable will self-adjust as you do this. once this self adjustment is done a quick check for any hangups or binding is a good idea.

Finally, Test drive the vehicle and check that it shifts from first to second gear at 15 to 20 mph, from second to third at 25 to 30 mph and from third to fourth at 40 to 45 mph. If the cable is adjusted too loosely your transmission will exhibit soft, stacked shifts (not spread out). DO NOT CONTINUE DRIVING VEHICLE IF THIS HAPPENS! Immediately readjust cable.

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