Help identifying TV cable

[GoToGuy]

Rather than just guessing, why don't you get the service manual for your year. Download it here in forum.
You know, if you don't know what it is, don't touch it.
With that you could look at the RPO codes and actually know what your truck is equipped with.

 

[Blue-88]

Rather than just guessing, why don't you get the service manual for your year. Download it here in forum.
You know, if you don't know what it is, don't touch it.
With that you could look at the RPO codes and actually know what your truck is equipped with.

Thanks

 

[L31MaxExpress]

TH350 was no longer an option after about 1984. The 3 speed option was a TH400. On TBI trucks there is not a mechanical switch for kickdown. It is done of the TPS and ECM through a Kickdown Relay (Uses the TCC output pin on the ECM). If you no longer have kickdown, first place to check is that your throttle cable can fully open the throttle body.

 

[someotherguy]

"3L80" 3-speed automatic / 1:1 final drive, TH400 with the new naming convention.

Ditch the TBI spacer. It's probably interfering with cable travel.

Richard

 

[Schurkey]

If I'm not mistaken you can adjust shift points by changing weights and springs on the governor but, someone else will have to confirm that.

Yes. The governor controls shift points, with some added input from the modulator.

But apparently kickdown is set by the computer. In the old days, the "self-adjusting" switches would go out of adjustment and need to be reset. But I guess that's no longer a concern with these.

 

[L31MaxExpress]

Yes. The governor controls shift points, with some added input from the modulator.

But apparently kickdown is set by the computer. In the old days, the "self-adjusting" switches would go out of adjustment and need to be reset. But I guess that's no longer a concern with these.

There is a relay that sometimes goes bad. It is identical to the early style fuel pump relay with the large oval weatherpack connector. On the 87 G20 305/TH400 setup I had the kickdown relay and fuel pump relay were one the same bracket on the firewall. The fuel pump prime terminal was also in the same spot.

 

[Erik the Awful]

If I'm not mistaken you can adjust shift points by changing weights and springs on the governor but, someone else will have to confirm that.

Yes. The governor controls shift points, with some added input from the modulator.

The shift points are a balance between the governor and the vacuum modulator. You can adjust the shift points if you swap to an adjustable vacuum modulator.

ATP Automotive JX-66 ATP Automatic Transmission Modulator Valves | Summit Racing

Free Shipping - ATP Automatic Transmission Modulator Valves with qualifying orders of $99. Shop Automatic Transmission Modulators at Summit Racing.

www.summitracing.com

 

[Schurkey]

Yeah, you can adjust the modulator within fairly tight limits. It's unlikely that there are many OEM modulators out there that are still functioning, but even the OEM modulators are adjustable. You may have to break the spot-weld holding the adjustment screw, though.

Nice thing about the OEM modulators is that they're altitude-compensated (which is why they're so much bigger than the cheap aftermarket units.)

The much-better way is to adjust the governor.

TH350, TH400, and TH700/4L60 all use the same governor calibration kit.
www.summitracing.com/parts/bmm-20248

B&M 20248 B&M Governor Recalibration Kits | Summit Racing

Free Shipping - B&M Governor Recalibration Kits with qualifying orders of $109. Shop Automatic Transmission Governor Recalibration Kits at Summit Racing.

www.summitracing.com

 

[Erik the Awful]

On a side note, I run the TH400 in my big-block Cadillac powered Jaguar with no kickdown switch. The motor's a torque god and downshifting only slows it down. The TH400 has no problem running that way.

 

[Blue-88]

On a side note, I run the TH400 in my big-block Cadillac powered Jaguar with no kickdown switch. The motor's a torque god and downshifting only slows it down. The TH400 has no problem running that way.

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