I took my 70 GS455 in to my favorite Buick repair shop last week to have the transmission leaks taken care of. I ordered a kit of "external seal up gaskets/O-rings. The main leaks were from the speedometer housing, oil pan, tail shaft and dip stick. I got it back Friday and all oil leaks have been fixed but, the Turbo400 has two problems that were not there before the car went in. 1) The kickdown is now inoperative at any speed. (It has worked flawlessly up till the shop visit) 2) The full throttle shift points are now occurring at 4800 instead of 5500 RPM. About 6 months ago, I went through the governor mod procedure and had shift points set at exactly 5500 in both upshifts and it was working perfectly every time. I'm taking the car back on Monday but want some ideas of what could have happened during the leak repair effort that could cause one or both of these issues? I hate to have to deal with "Well, we didn't do anything that could have caused that" response and hope the shop will take care of the issues since I've been dealing with them for over 25 years. I just want to get some ideas from some knowledgeable transmission authorities before taking the car in.
The kickdown could be the external case connector terminal on the driver's side not connected, or the wire to the solenoid on the back side of the case connector inside the transmission do not get re-connected when the or ring was replaced. If the kickdown switch is not connected, that can cause early upshifts as well. Check the modulator hose for good connection and vacuum leak. Corrected. This would cause late upshift... Those are the most likely issues since the rest of the car was not involved.
Just the fact that the kick down is inoperative will cause the transmission to short shift, so that is 2 effects from the same cause. Check to see if the wires are connected to the transmission, and at the gas pedal.
It’s been a long time since I had a similar problem, but I ‘think’ there’s a fuse for the kickdown also… Patrick
Yes, it’s the fuse that protects the kick down, radio, and power accessories. Radio works so fuse should be good.
It's something stupid simple like: the cable is disconnedted on one end or the other or vacuum modulator tube didn't get reconnected. They'll find it right away, they're face will turn red and they'll apologize.
I'd check the plug on the trans before getting too excited about it. They probably left it unplugged.
Looks like it’s connected but I can’t reach it. The good news is that my tranny that has leaked from numerous places ever since I’ve owned it is now dry as a bone.
Ray, If they replaced the rubber 0-ring on the pass thru plug that you show in the picture, it then very likely that they forgot to hook the wire back to it internally. No need to get under the car to diagnose this.. just unplug the two wire connector at the detent switch at the gas pedal, and test the brown/white or black/white wire to ground to see if it is an open circuit. The yellow or pink wire in that connector powers the switch. Sorry for not knowing exactly the colors of the wires, it's probably been a decade since I have fooled with that circuit. With an ohm meter, you should be able to read the resistance of the solenoid coil. JW
Thanks Jim. Actually did run it back to KDK and Rob had indeed left the wire off when he replaced both the O ring, the pan gasket, and all the other external leaks. That’s the good news……,the bad news is on my way home the kickdown still doesn’t work! When I get a moment next day or so, I’ll troubleshoot the wiring including your suggestion and post back what I find. In the meantime I’ve got a kickdown switch, a case 2 prong pass through connector, and a new detent solenoid to cover all the bases.
The modern kick down switches, which look the same as the old ones are garbage in my experince. My original lasted 53 years. The replacement less than 2. I paid extra this time for a Lectric Limited branded switch, but it looks identical to the cheap one, so we shall see.
Ray, Just run a jumper wire from the battery positive terminal, and touch the connector on the side of the transmission. If the solenoid is working, you'll hear a click every time you touch the connector. That way, you know whether the problem is still inside the pan, or upstream towards the gas pedal switch and/or wiring.
You can test connectivity of the system before running jumper wires etc. First I would use a test light with the key on to check and see if there is power coming through the harness to the switch above the gas pedal. If there is power, then. With no external noise in the work area turn the ignition to the run position, reach under the dash and pull the activation switch above the gas pedal reward to activate the kickdown, listen for a click in the transmission. If there is no click then use the test light to see if there is power going through the switch to the other wire going to the transmission. If there is power then it is possible the wire on the inside the connector on the transmission is not connected properly.
Thanks, Dave. I'm familiar with the test procedure but won't be able to get to it until the weekend. I want to have the case connector, kickdown switch, and new detent solenoid here just in case one is bad although I suspect it's something simple.
