Hey guys I installed 2 new 9a SFE fuses in my Trans Fuse Box area for my 66 f85 and it has blown twice in a week. This is the fuse for the variable vane and the kickdown. Any idea where the short may be coming from, could it be a bad solenoid inside the tranny. Thanks and I apprecaite your insight.

 

It could be anything from the fuse box to the transmission. The only way you will figure it out it to get out the multimeter and start testing the wiring and components.

 

Since that wire runs by the exhaust I'd start looking there. Sounds like a short to ground.

 

Disconnect the wire from your trasmission and see if you get 12v and if the fuse pops with it disconnected. This will eliminate all the wiring from the fuse box, through the switch on your linkage. The only other thing that comes to mind is if your is the round assy on your throttle linkage, possibly it came apart internally and is shorting inside.

If everything checks good without the trans hooked up then its at/ or in the trans.

 

Thanks for the help guys. Still havent figured it out, only played with it a few times. Now blows fuses as soon as the car turns on. I checked to see the wires going from the carb linkage down to the tranny and they are not exposed or touching any metal, never hit exhaust. I also disconnected all the wires at the carb linkage and the fuse was fine, then I connected the 12v red wire and the fuse was still fine and upon connecting the double yellow and back (vane and downshift) wire the fuse blew. I am starting to think its the round throttle assembly mechanism, any ideas if they sell this piece or what would be involved in rebuilding the one I have. I really miss my downshift and switch pitch I think its a great feature.

 

I've rebuilt mine and it's not that hard to do if you're willing to try. My only caution would be you're not going to find replacement parts for it readily. So if you take it apart and a piece is totally fubared you'll have to fix it somehow on your own. Mine was in relatively good shape when I took it apart and I only found one contact that was rubbed through so I just put a spot of solder on it and fixed it that way. It's more intimidating than it really is but at some point you'll have to remove a staked tab and figure out how to replace it, I used a screw and washer. In the 4th picture you can see the soldered contact in the upper right.

 

More pics. In these you can see the screw replacing the staked connection on the backside of the switch itself.

 

I sent you a PM back and I was just thinking that you can also bypass the throttle assy through a couple of toggle switches and see if the fuse still blows! This would eliminate it.

Also If you have an ohm meter you can ohm out all three contacts to see if they are shorting to the housing.

 

Experimented yesterday for a few hours with a body and a multimeter. Short is def coming from the tranny. We tested wire going to tranny and was showing overload and still blowing fuse. After disconnecting connection at tranny fuse remained fine. Must either be a shorted wire in the tranny or a bad solenoid which I have had a hard time finding.

 

The wire may have worn through and is shorting out to the tranny itself or the solenoid is stuck.

 

Dropping the pan tonight, hopefully its just a wire as I have not been able to find a solenoid anywhere. I am hoping that one of the 2 internal wires will be visibly worn. If not I will remove the solenoid and try to clean it out. Is the solenoid pretty easy to access.

 

You'll see two solenoids when you drop the pan. The top wire on the connector is the S/P wire, bottom is the downshift.

 

TripDeuces,
After a nice long messy night yesterday we got the kickdown to start working again but not the s/p. Upon removing the pan I noticed the detent/kickdown wire was cracked and easily able to short, I removed the solenoid along with wire and resealed it with heat shrink tubing. The stator wire looked intact and fine so I connected the wires back to the case connector and tried a new fuse and agin it blew instantly. I then individually connected the detent wire and the fuse did not pop. So how do you get to the stator wire solenoid it appears to be behind the torque converter and I was not in the mood to remove the tranny or torque converter. Having a kickdown is good enough for now but I would like to have the switch pitch work down the road.

 

http://www.buickperformance.com/switchpitch.htm

If you look at this article there is a picture of three front pumps about 2/3 way down. The one on the left is the S/P unit and you can clearly see the solenoid facing toward the front. Unfortunately it requires removing the front pump.

It appears your tranny is getting too hot. Back in April I had mine open and the wires looked great after a few decades of service. Very pliable and no breaks anywhere. As far as a new solenoid Phoenix Transmissions http://www.phoenixtrans.com/ is now doing S/P TH400s. Maybe they can hook you up with a replacement. GL to you and keep us informed on how you make out.

Are you sure it's the solenoid and not the throttle assembly itself? They do go bad as evidenced by mine. I now have my S/P controlled by a momentary switch for on or off but plan to use a delay timer relay in the future. It will activate when the brakes are applied and after a set delay (2-3 seconds) will go back to low stall. That way I bypass the throttle assembly all together. Another alternative is Bruce Roe who makes a control box for the S/P that is a little more involved.

 

Yea its def at the tranny. I ran the throttle wire connected but off at the tranny and not pop fuse also the multimeter was showing good 12v while opening throttle and WOT at the throttle linkage. Also As soon as I connected the wire back to the tranny after not popping the fuse with it disconnected, it burned up in a second or two.