Hmmmmmm

 

Reminds me... Better put in a new speedo cable while I'm down there. I think I'm just going to hook up a couple of switches. One that flips the circuit open when I hit the brake and a manual toggle switch near the shifter. Maybe I'll even be creative and use the dremel and make it look like it's supposed to be there.

Not sure if my Haynes guide has the wiring diagrams so could someone direct me to a link for the wiring diagrams?

 

Are there just two terminals comming off that TCC and is it just a wire soldered between the two and what gage wire was used.

 

I'm interested in that myself, now. What the hell do they have hooked up there?

 

Hi,
Just been pointed to this post (life's been busy lately, but I'm still about!). For a stock '81, with no wiring mods & just the computer removed/dead then the fix is simple. If you leave the TCC/EGR relay in place on the firewall then all you need to do is simulate what the computer used to do...... which is simply connect an earth wire to earth. I can't find my notes on it but the wiring in mine (& 2 others I looked at) didn't match the pics posted on the previous page & in the manual regarding the internal trans stuff.
This is how mine (& 2 others) were wired up:

A permanent 12v is fed via the connector on the trans to the TCC solenoid (how it works in the trans is a complete headache, you just need to run 12v through it to get it to work, so don't worry about what's going on in there!). This 12v needs to be earthed for current to flow & the solenoid to kick in & lock up the converter. The earth path from the trans goes to the TCC/EGR relay on the firewall &, when the relay is switched, it gets earthed. So, when the relay switches then the TCC will lockup as there is a completed circuit (the earth wire from the trans is tan/black & goes to pin E on the relay & comes from pin D on the trans. However, the connecter for the trans harness has a plug just to the rear of the d.side valve cover & the pin numbers don't match! Pin D on the trans goes to pin B on the connector plug. Confused yet?! The earth path FROM the RELAY is a black/white wire connected to pin A.).
So that's the circuit for the trans taken care of, it switches on/off TCC lockup by switching a relay. The relay switching is quite simple. All a relay does is throw a switch inside itself when a little coil energises due to current flowing through it. The switch in this case is used for cutting/supplying power to the trans. To switch the relay a current has to be fed via another 2 pins on it. 12v is supplied to pin C on the relay (ppl - purple(?) wire) but the nifty thing is that this isn't a permanent 12v - it comes from the TCC brake switch ie when the brake is on then this 12v is switched off & the relay won't be switched (or will be switched off it it was), unlocking the TCC. The earth path for this 12v is out on pin B via a black/tan wire to the computer. So, when the computer wants lockup it connects this wire to earth. A small current will flow through it (as long as the brake isn't on) which will then switch the relay. Switching the relay will allow current to flow through the trans & lockup will occur (assuming the trans is working OK).
To remove the computer's function you can either connect the wire to it directly to earth (as I've done with my Th220-4r) or hook it up to a switch that connects it to earth so that you can choose when the converter can lockup (but still be unlocked whenever the brake is pressed).
Effectively there's 2 circuits. One supplies power to the trans & is turned on/off by the relay. The other circuit is the one that switches the realy on/off. This circuit is broken by both the brake light switch & by the computer, so both the brake light switch & the computer can switch the realy off by cutting power to it. Hope this makes sense?
Here's the nice bit. There's a TCC diagnostics connector in the harness. It took some searching, but I found it under the right console side cover. It's about level with the ashtray & is a black plastic connector about 3/4" long (I think?). At each end a black/tan wire comes out of it & there's no way that it pulls apart. But there's an exposed spade terminal in it that should (with an AVO) buzz out to show a direct connection to pin B of the TCC relay. The other wire from it runs to the computer. Hooking in to this test point will save chopping wires about, just run a wire from this test point directly to earth (for permanent lockup) or run it to a switch that will earth it when thrown. Hopefully that will get the TCC lockup up & running (plus you'll also have an idea of how it works - apart from the tricky bit inside the trans!). What I've done with my 200-4r is effectively connect the wire directly & permanently to earth. The TCC locks up about 1 sec after the trans shifts into OD & that's fine with me. An OD trans needs to be manually shifted down into 3 as the vehicle slows, so having the converter permanently locked in OD isn't a problem as I've manually downshifted before the engine starts lugging. I can't remember if the Th350C downshifts into 2 before the revs drop enough for it to lug with the converter locked? I guess the thing to do would be to suck it & see.
I've got a pic I've done in a Word doc that I can email (or could somebody host it????), which shows how mine (& 2 others) was wired as stock. Wire colors are meaningless as every wire I looked at was a uniform dirty grey-brown!
Inside the trans is a pressure switch that's wired in series with the solenoid. What this does (I've been told) is to cut the circuit at low pressures. Low pressures occur in the low gears & at low speed in top gear. This makes sense as it will prevent lockup in the first 2 gears (can't see how the computer could determine what gear the car is in - & it can't base it on vehicle speed as it might be doing 70mph in 2nd gear. It could look at rpms & vehicle speed to work it out, but that seems a bit complicated for the simple system used in '81. Plus it'd make rear ratio changes a pits, so it makes sense that the pressure switch is to preven lockup in low gears).
The wire that goes to pin C on the transmission connector didn't go anywhere in mine, it's just an extra wire that doesn't do anything.

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NB. To determine if the TCC lockup is working OK in the trans then you can jump the earth from it directly to an earth point. This earth is the wire from pin D on the trans, which goes to pin B on the connector & then joins to pin E on the relay. You can either jump into it with a probe or do what I did. I unpluged the connector next to the firewall on the end of the harness to the trans & then used a short length of wire to jump Pin A on both halves of the connector (so 12v was still getting to the trans). I think I used a couple of matchsticks to hold the wire in the connector - use something as it's a 12v supply & could short out if the wire falls out. For earthing it I stuck a long wire into pin B (D??) in the socket FROM the trans ie the part of the plug with wires going down to the trans, not the 1/2 connected to the harness along the firewall. The next bit's good. Run this wire through the drivers window and hand the bared end to a passenger (I used the GF, as usual ). Run the car up to about 60mph & ask your passenger to earth the wire. I got the GF to kneel over the seat & touch it on the NEGATIVE post on the battery (make sure you explain clearly which one is negative!). You may want to adjust your mirror for this part If the trans internals & the short harness to it are OK then the TCC should lock when the wire is earthed.
For anybody having problems with the stock system, here's what I found wrong with mine: the computer wasn't requesting lockup at all. Ever. It took me about a year (I'm a bit slow at times!) but I eventually realised that it stopped locking up sometime after I swapped out the speedo for a 140mph unit & also fitted a 180 stat. It could be that the VSS in the new speedo doesn't work (so the computer is saying "Hey, we ain't moving, I'm not locking the converter") or the coolant temp isn't getting hot enough (so it's saying "The trans fluid probably isn't warm enough yet, I'll hold off requesting lockup"). The problem for me was that I didn't realise that it had stopped working, not until fuel costs were getting stupid did I notice. BUT, connecting power directly through the trans didn't get it to lockup either (& nearly caused an accident as I was concentrating on the view in the mirror ). After fitting the OD trans I pulled the pan off of the old 350c. I'd already changed out the solenoid & pressure switch & not got it working, so had a spare evening to see what I could find. Under the TCC solenoid is a little fluid passage that's crucial for TCC lockup to work. My one was full of gunge. It's amazing how much extra you can see when the trans is on a bench & you're looking at it with a beer in hand, instead of laying under a car in the dark with fluid dripping all over your head! I thought it was a bit of a coincidence for the confuser AND the trans to go wrong at the same time, but a trans expert has told me that it could be due to the computer not requesting lockup. After that happened, the passage wasn't used for high pressure fluid so the slag & gunge floating around inside just sort of accumulated in it & blocked it solid.

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Hope this helps!

 

I'm back (needed a coffee after that last post!).
A relay is used in a system partly to prevent heavy electrical loads passing through switches & thin wires, etc. The TCC/EGR realy supplies power to 2 systems, but mine didn't have the EGR stuff when I bought it, so only power for the TCC was going through it. I measured the resistance of the new TCC solenoid I bought & worked out that current flow through the system was small, but I've forgotten what it was (0.5A???), so I reckon the relay can be bypassed completely.
To wire it up the simplest way possible you just need to connect the wire from the TCC brake switch to pin A on the trans connector & then run the earth wire from the trans to an earth, or to a switch if you want the manual option. Here's how I'd do it (or about what I did with my OD trans as it needed different wiring):

Snip off the wire on pin C of the relay connector. This should be ppl (purple? Brown on mine - like every other darn wire I looked at) & is the 12v supply coming from the TCC brake switch. Then go to the connector in the harness coming up from the trans & snip the wire on pin A (pnk/blk - this was the permanent 12v supply). Then connect the ppl wire to the connector so that it goes down to the trans. You've now got 12v going to the trans from the TCC brake switch ie. step on the brake & the TCC will unlock. Then take the wire on pin D (B?) on the connector (which goes to E on the relay) & connect it to an earth (for permanent lockup when in top gear) or route it via a switch in the cabin to earth (so you can manually unlock it). To make things easy I'd cut the wire from D (B?) on the trans harness connector & then cut the wire on pin B of the relay connector. Join the wire that was on B of the relay to the connector to the trans on pin B (D?). You've now got the earth from the trans connector running through the wire that used to go directly to the computer ie. the one with the handy diag connector in it under the centre console. Either fit a switch in the cabin (that diag connector would make it simple to fit a switch in the console cover) or just connect the wire directly to earth. Make sure that the computer is disconnected as, if it's messed up, it may be connecting that black/tan wire anywhere!
When cutting wires from connectors always leave a small length in place from the connector so that you can solder wires to it (or go back to standard if you ever want/need to).
An alternative is to take the wire from pin D on the trans directly to earth & connect the ppl wire to pin A on the trans as I've described above (which will give lockup whenever in 3, apart from when the brake is pressed). A manual switch could be easier to fit in the ppl wire? This wire is in the cabin as it goes to the brake switch, so it might be easy to get to so that a switch can be fitted in it. Then the brake switch, & the new switch, can be used to cut power to the TCC. It doesn't matter if the manual switch is fitted in the feed to the trans, or in the return, but I'd see what the easiest wire to get to is. What I remember of adjusting the TCC brake switch is that it's a job for a 3 handed contortionist, but the wire from it might be in an easy to reach position?
NB. the above is assuming that the EGR system has been removed. Mine had, but doing the above snipping of wires will stop it working if it's still on there. If somebody can host the pic I've got it should make all the ramblings a lot clearer!

 

I put a TH350C in my 68 chevy truck. Put a line from the fuse block, through a toggle switch on the dash, then to the plug in the tranny, the other line was ground and went directly to the frame. The toggle was normally in the off position, but I would engage the lockup when at crusing speed and had a direct drive for what it was worth. I did have one problem though I did not put a grommet in the hole through the firewall for my + wire and it ended up shorting out. That was my dumb mistake. fixed that and worked great.

 

Check out Paul, free pic hosting, essentially.

Basically it all makes sense, however, pictures would certainly help! Haha. I have to thank ya much as you made it sound pretty simple with the wire splicing. I want to go with the brake and manual switch method, as I don't drive it every day any more, although my egr is still there, I don't know how much longer it will stay there! Also, I drive in 3rd gear around town a lot as it just kinda hums at 1k rpm doing 30 mph. Don't want lock-up at that speed!

Now here's a question, when I hit the brake, how will I make it flip my manual switch off? The way you describe it, if I hit the brake the tcc will disengage, but what about when I let off the brake? Will it re-engage?

 

Hi,
Keeping the EGR makes it a little bit more tricky if you want to tidy up the wiring/firewall, etc. If you just want to get the TCC working then pull off the console LHS cover & find the little black diag connector/block/thingy under there. Get an AVO to buzz it through & make sure that you've got the correct wire (should get continuity to the wire on pin B on the TCC/EGR relay). I'd recommend pulling the connector off of the relay to buzz it through as you're never quite sure what's connected to what otherwise & you might get a false reading as there's a path via some tortuous route in the wiring of the car. To identify the TCC/EGR relay just look at the little bracket stuck on the firewall directly in front of the drivers seat. From memory there should be a pressure sensor (MAP???) & a couple of relays. The one you want is the one with wires connected to all pins except D. There's also another relay there (AIR?) which has different pins wired up.
So, once you're sure that the little black plastic thing is the correct test connector, you just need to do what the computer did with it ie. connect it to earth when you want lockup. I'd cut the wire, myself (mainly because I never traced it back to the computer so it could be joined to some other wire, etc, etc). Then connect the end that heads towards the front of the car to earth. That'll give lockup whenever in "3". I was going to mount a switch in the console cover (near the ashtray) & connect the wire to one side of it (as it's so close it should be easy to do). The other side of the switch will just need a wire run to a decent earth point (there must be one under that console somewhere). So now you'd have lockup when in "3" with the option to turn it off with the switch.
The TCC brake switch will still be in the circuit as it's still supplying power to the relay (which is still being used with the above wiring). Whenever you step on the brake the TCC will unlock, whether you want it to or not. I've adjusted the TCC switch on my brake pedal to be very sensitive & it cuts the power as soon as the pedal is depressed very slightly (Sensitive? Depressed? After adjusting that TCC brake switch, you will be. Also sore :lol). I haven't fitted a manual switch as I'm happy for the converter to lock whenever I'm in OD but if I gently touch the brake pedal the converter will unlock, locking back up again when I take my foot off of the brake (this is an easy way to check that the converter is locking).
As the EGR system is controlled by the computer, using the same relay as the TCC, I'm not sure what doing the above will do for the EGR system (mine was never connected so I never had to find out). I'm guessing that it'll work OK apart from 2 things. The first is if you're hurtling down the road with the TCC set to unlocked with the manual switch. This will probably stop the EGR from doing whatever it should be doing. A problem? Don't think so, they run fine without EGR connected! The second is that if you start fom cold & immediately let the TCC lock then the EGR system could start working before it should (the computer seems to wait for coolant temps to rise before switching in the TCC lockup & I'm guessing that also applies to the EGR as the wiring for the 2 systems looks common). Will this be a problem? I don't honestly know. All I can suggest is trying it & seeing what happens. If there's a problem (maybe exhaust gas injected when cold will cause stumbling?) then you could just set the manual switch to the unlocked position until the engine warms up. Or..... if you're careful about where you cut the wire you can always put it back to stock! Actually, that wouldn't be a bad idea, if the wiring on yours is different to mine then I could have fed you a complete bunch of BS As I said earlier, mine was the same as 2 others, but mine also had 2 extra solenoids/relays on a bracket at the rear of the p.side valve cover. All other '81 owners I've asked only had 1 & it was called the EGR bleed solenoid (or something like that). Mine had an extra thing doing something with the EGR system so I really haven't a clue what's going on with EGR, which is why I think you'd best check that it seems to work OK after doing the mod. Or just pull it all off - there's a lot less vacuum pipes/wiring to worry about if you do!!!
If you IM me your email address I'll send you the pic I did of the stock wiring (so you can check yours is the same before cutting wires).

Edit: LOOKOUT!!!!! The TCC diag connector is under the LEFT console side cover, NOT the right as I said earlier (wrote it all from memory & I was facing the back of the car when I was doing it and, well, you know how it is, left, right, forward, backwards, it's all relative...

 

After driving tonight, I think for the quick fix I may just let it lock up when ever I put it on 3. So I just basically jumper a that one wire to ground and it does that, correct? I'll hook up a switch when I want to dig out wires a bit.

 

Yep, that should do it As long as all the wiring is still in place then that would be the easiest way to do it.
Email on its way

 

Curious, the way we jumper computer power supplies when we want them to turn on without a computer is we stick a paper clip in to the two holes we need jumpered, while it's powered off. You say the diagnostic plug has both of the wires needed, so would that be feasible? Or would there be problems with such a crude and easy method? You know us confuser technicians, always trying to cheat.

 

Ok I'm digging under my center console and I found a thing that looks like a diagnostic connector. It has 5 wires, though, and they're green, orange, yellow, red and brown. Is this what I'm looking for? If so, which two wires do I connect?

 

Ooop wrong one, found the right one, now! It has 2 black, 1 white, 1 blue, and 1 brown. Which two do I splice together?

 

It looks pretty simple the way it's explained.

http://www.smokemup.com/tech/700r4.php

 

That says Pin A to Pin D... lets see what colors those are!

 

I THINK I got it, but how do I tell if it's locking up? I apparently got something hooked up because the check engine light is on again! I connected the Black with the white stripe to the brown with the white stripe, I hope that's the right ones!

 

On my 1980 when the shop hooked up the wrong wire to the trans I got a "choke" light and my gages went dead (no check engine light). It could be that you are grounding the wrong wire.

 

UK paul i have to save to read

 

hrm my tach is working fine just not sure how to tell if it's locking up or not.