Throttle Valve Cable

The THM 440T4 transmission in this car uses a TV cable to determine shift points. This cable comes from the top of the valve body near the top of the bellhousing, and routs to the throttle arm on the throttle body. Because of the location of the turbo, this area is exposed to high temperatures beyond what the plastic cable could withstand.

Any sticking or binding of this cable will result in altered transmission operation. It can lead to trans failure or at the very least make you think the trans has failed!

The original one had literally melted down and the plastic sheath fused to the cable core effectively locking it. The adjsuter broke next time I stepped on the gas and I had an early shifting-out symptom.

The solution was to fabricate an all-metal TV cable end and extend this up away from the heat with steel tubing for a sheath. These pictures show the solution.

The fitting that mates to the transmission is made of 3/8" steel pipe. The flange is welded on. Onto that is screwed a 3/8x1/8 brass reducing coupling with a 1/8nptx5/15 inverted flare adapter. Into this goes the steel tube cable sheath. The cable core is installed in this picture. The end crimped onto the core fits a wire "hook" protruding from the transmission. When the cable is pulled, this hook is drawn up into the pipe section.

Here you can see the original plastic (and very crispy) cable end, and a close-up of the new one. You can see the co-axial 5/16 and 3/16 steel tubing which forms the new all-metal cable sheath.

Here's the complete customized TV cable assembly, with the original end sitting in the middle of it.

Cable can be seen going between the downpipe and wastegate.

A closer view of all-metal TV cable going between very hot parts!