How to understand 80s Silverado/Sierra TCC lockup

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Comments "How to understand 80s Silverado/Sierra TCC lockup":

Author: Makasa
Give it gas and it won't accelerate give a bunch of gas still won't accelerate. then after that it just downshifts into third again.
Author: Zugor
Sir I'm trying to help a friend get his truck ready to install the MSD EFI kit. It chevy truck is a 1984 Would you know if I would still need to install a lock up kit in his trans? Thank you sir!!
Author: Grosar
Can an 87 that has been converted to carb run this vacuum style lockup?
Author: Akinotilar
Ok, so there are three switches inside the trans that will interrupt the signal from terminal A on the trans plug. First one is before the solenoid coil, and it opens on a 4 to 3 shift. Then between the solenoid and the next sw is a temp sw so trans must be up to temp, however if term D is grounded this and the next sw are bypassed. Next the temp sw feeds a 4th gear pressure sw, so it must be in 4th gear unless term D or B is grounded. Term B can bypass the second 4th gear sw, but nothing can bypass the 4-3 open sw but I that is just a pulse, so unless Term B or D is grounded it can only lock up in 4th gear. I'd post the schematic, but I don't have a good way.
Author: Gardagul
P.S. this is a California van with no computer or cats. That's the way 8600 GVW came from the factory
Author: Arara
I have a th350 from an 83 3/4 ton van. I didn’t see a plug on the side. Would love to buy a lock up converter and modify it to work. Any ideas
Author: Mukazahn
Greetings! First I would like to thank you for making these informative videos for all of us backyard mechanics. I watch your video on replacing the TCC solenoid and it was a breeze. I'm working on a 1982 Oldsmobile Toronado with a TH325-4L transmission. Just bought it and I'm trying to work out the bugs from prior mechanics. The carburetor has be switched to a non computer q-jet. It's EGR delete and has a vacuum advance distributor. I ran the check engine light for codes and it showed 12 for no issues. Can I run this set up you are showing here on this TH325-4L. Reading blogs online everyone is talking about needing a toggle switch to perform the converter lockup. Any thoughts on this? Unfortunately, for me these front wheel drive cars like Toronados are hard to find information on because these transmissions are strange animals. Thank you in advance for any insight you may provide.
Author: Zulkigore
did you buy an 80's silverado?
Author: Brazshura
So another words using the vacum switch to control the lockup torque converter ....why can you just use a passing gear switch for a th 400 transmission instead of the vacum switch or a toggle switch
Author: Yozshuk
Hi Tyler. I just came across this video and I'm really excited about how you explain the lock up in these old chevy trucks. I have a 1983 chevy c10 and had no idea how the lock up worked. You have taught me a lot and answered a lot of questions. Now, I have another question for you. My truck originally came with a 305 but in 2006 I put a new chevy 350 crate motor in it. I have had a lot of trouble with vibrations and loss of power 40mph and higher ever since I put that motor in it. I've done all of the expected changes to try and solve the vibration problems...rebuilt transmission, new torque converter, distributor, carb, ujoints, on and on. You mention in your video about a second vacuum switch on the 305 passenger side that looks like the TCC. I have that passenger side vacuum switch and would like to hear more about what it does and if this could be the culprit in making my truck vibrate, lose power. The original distributor did have a wiring harness that came out on the side and clipped into a harness coming from the firewall. I was advised NOT to use that type of distributor and the new distributor does not use that harness, but I do see that the vacuum switch has a wire that looks like it is part of that firewall harness. Have I messed things up mechanically with the new motor and distributor? Am I finally, after years of work, zeroing in on the problem? Thanks in advance for your help Tyler.
Author: Tauhn
My trans shifts into OD fine but feels like it is slipping in OD
Author: Aragor
So I just drive around in drive not overdrive..
Author: Zulur
Hey Tyler, good video. Some of these trucks did in fact have an ecm with a feedback quadrajet. Certain 83-86 models, i believe the california emissions certified trucks. The tcc was controlled by the ecm.
Author: JoJogar
Great video... I have that on my G30 van.. i have replaced the vacuum line to it, but I still don't get lock up but once in a blue moon... Thank you for your explanation
Author: JoJoshicage
You did a GREAT JOB on this video! Very thorough . May I make a suggestion, in your explaining of 2 different vacuum switches, remember to always and only describe the locations of a vehicle as ,front or rear; and not right or left, but as drivers or passengers side. Example your vacuum switch was correct as drivers front side of firewall.
Author: Male
What if you swapped in a edelbrock carb.
Author: Zululkis
I think im just gonna install a oil pressur switch and wire my + to it up to that plug amd the other wire to ground and let the trans pressure do it on its own
Author: Mucage
Actually, you can wire it to have constant power and it will lock in 2nd, 3rd, and 4th on its own and unlock by itself in first gear. The way the valve body is, the converter will not lock up in first gear. I have mine set up this way, but I added a relay coming off of the brake light switch so when I step on the brake, it cuts power and unlocks the converter. I've been driving my 89 S10 with the original transmission like this for the last three years. It has 210K miles on it and three years ago is when I put a 350 in front of that transmission.
Author: Gara
Question. My 84 C10 has a shudder only in lock up, under very slight load. Any temp. Bad converter? Should I just just disconnect the lock up and keep rolling? I would like to keep the lock up.
Author: Shaktile
Of course being that the internet is world wide, some places overseas the drivers side could be of different side . Anyway wow what a great video, you impressed me ,THANK YOU SIR.
Author: Majinn
And show color of wires to confirm right switch and or circuit.
Author: Dourr
Years ago I had an old 1990 Cavalier, and I had to replace the lockup solenoid.. was easy fixed the stalling when coming to a stop.. I remember have to backup to unlock it.. lol
Author: Mitilar
Another enhancement would confirm , pull some tape off wires near plug end
Author: Tygoll
Excellent explanation, never had one of these but good to know.
Author: Vigul
do you have to have the check valve on there for it to work?
Author: Feshura
Thanks I got mine working ? For the distributor with vacuum do you hook up to
Author: Shaktimi
You are Great. Thanks!
Author: Kagakora
Trans seem extremely confused all the time
Author: Shakahn
I'd appreciate any feedback on this as I may be missing something I don't know.Update:Ok so I have completely redone my lockup system now and here is what I have done and found out.1. The power for the lockup comes from one of the plug type connectors on the top of your fuse panel.2. That wire goes to the brake pedal sw which is on the passenger side of the steering column just under the dash (remove the little middle dash panel)3. From the brake peddle it goes to the Vacuum sw (on the firewall next to the Brake Booster) There is ANOTHER Vac sw on the Passenger side, that is tip in Vac for spark control and is NOT part of TCC.4. This is where it goes south. The wire from here goes to the Transmission, AND the EGR bleed valve (above the EGR valve on a brkt on the engine). and there is another wire that come back from the transmission for what IDK.ANYWAY here is what I did. I took the wire from the Vacuum sw and bought a new connector for the transmission, wired the switch leg from the Vac sw to the 4th gear pressure switch (inside the Tans pan back Drivers corner right by the Accumulator I think it's 2nd gear Accumulator not sure), from there I went back to the trans connecter on an different pin and back inside the cab, AND the same wire from the 4th gear pressure sw to the TCC solenoid valve ( inside the trans pan in the front just to the drivers side of middle) then took the black wire from there and put a ring terminal on it and put that under the mounting bolt for the Solenoid.The wire inside the cab is the same as solenoid power so I hooked t to an LED indicator so I know when the solenoid is energized.Now after driving for a while I noticed that using Tip in Vacuum for the Vac sw source caused way to many lockups and unlock cycles and since I don't like wearing out the TCC clutch I switched it to manifold vacuum which does not go away just because I let off the throttle when I'm goin down a hill at 75 MPH which I like, no need to unlock for that. I am still considering getting rid of the  Vacuum switch all together as I think then it would cycle even less, and if I step on it it's going to kick down to 3rd and unlock anyway. Currently I get a little flutter out o fit just before it kicks down since the governor pressure is just below kick down pressure when the TC unlocks and that changes engine RPM and then that changes governor pressure and Engine Vacuum which then relocks the TCC then it kicks down and unlocks on the 4th gear pressure sw. all this is too complicated for and old hardwired control system, so in the end I think I'll just use the Brake peddle and the 4th gear pressure sw for controls.Hope this helps anyone working on this. If not visit my page and message me and I'll try to get back to you.
Author: Goltijas
Why won't it stay in OD when I want to accelerate it's does nothing just feels like it's slipping???

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