How do i get the converter locking!!!!

[Deuling]

I have a 1985 K5 with a 700r4 code says 6TKM346H, which says its a 1986 tranny... lol . But anyway I dont think the torque converter is locking up in overdrive, It just doesnt feel right i guess... I know on my van and every other vehicle i have had that if you hit the break around cruising speed (55 or so) i could feel the torque converter let go.. When i hit the break in the Blazer it just slows down, but no change in tranny... I Guess im a little confused. I have read about buying wiring harnesses and stuff but i didnt know if their was a simple way to check something, like the cable. My haynes manual isnt doing it for me. Not enough pictures i guess..

 

[obijuan]

Call bowtie overdrives and pick up their torque convertor lockup kit. It's easy but their pics suck on the instructions. Do it on a weekday to you can call for tech support.

 

[Avery4jc]

How about more information on the blazer...
I know when I bought my k10 it had 38's w/o proper gearing and my 700r did some weird stuff.

 

[Deuling]

How about more information on the blazer...
I know when I bought my k10 it had 38's w/o proper gearing and my 700r did some weird stuff.

1985 K5, 32" x11.5" buckshot maxxis mudders (they are skinny but nasty treads) 3.73 gears with the G80 locking rearend. Np208 T case, edelbrock 1406 carb with e-choke, and edelbrock performer rpm intake (which i am looking to get rid of because its a 1500-6500 rpm rated intake..) But really stock looking

 

[Greg Ducato]

Check to be sure you are getting 12 volts to the transmission connector located on the drivers side of the transmission. With the vehicle running, you should have 12 volts to the "A" terminal, which is furthest to the front and outside on the connector. If you do not have 12 volts, trace it back to the brake switch, which may just be out of adjustment, or it could be a voltage source problem. If you do have 12 volts at the trans, and you have an 1986 transmission, you may have to run a seperate ground from the "D" terminal as this would normally be provided by the vehicle ecm. The "D" terminal is furthest to the outside and rear of the connector, right behicnd the "A" terminal. You can ground it to a pan bolt using a ring style connector for the sake of convenience. Once you have voltage, and a ground, you should have lockup function, if not then it is time to drop the pan and make sure the internal switches are hooked up and working.

 

[Blue85]

^^ What he said.

There are two circuits for lockup, but the 2nd one is for lockup below 4th gear. The first one is basically just a hot wire broken only by the brake switch. Measuring the voltage at the transmission connector separates whether the problem is inside or outside. I have fought the no-lockup several times. Here were the solutions some different times:
1) brake switch was mis-adjusted on the bracket (easy)
2) lockup solenoid had gone bad (replace solenoid)
3) TCC apply piston failed (replace torque converter)

 

[badmix]

My TQ wouldnt lock up because of the vacuum switch on the firewall. Its right beside the brake booster. It should go to ported vacuum source.

 

[Deuling]

Ok thanks guys. My boss is gonna let me work in the shop after work. Its only heated to 50 but idk about you guys but we got a good foot and a half of snow last night lol. So ill take what i can. But if you guys have any tips let me know. Ill check on my phone. Its a pain but better than nothing

 

[Blue85]

Another idea is to call transmission shops. There is a handy tool that plugs into the transmission connector with a little control box that reaches inside the cab. You go for a drive and it shows you what's going on. They may offer this diagnosis for free or a small fee. This is especially helpful for the 3rd gear lockup - you can get by without it for 4th gear since the signals don't depend on the engine.

 

[Deuling]

Ok i may have to try that. When you guys said to check for 12v at the terminal, is that plug a pain to pull off. Just dont wanna break it and be screwed. And to run a ground to d, do i have to splice a wire in?

 

[dabomb6608]

Check to be sure you are getting 12 volts to the transmission connector located on the drivers side of the transmission. With the vehicle running, you should have 12 volts to the "A" terminal, which is furthest to the front and outside on the connector. If you do not have 12 volts, trace it back to the brake switch, which may just be out of adjustment, or it could be a voltage source problem. If you do have 12 volts at the trans, and you have an 1986 transmission, you may have to run a seperate ground from the "D" terminal as this would normally be provided by the vehicle ecm. The "D" terminal is furthest to the outside and rear of the connector, right behicnd the "A" terminal. You can ground it to a pan bolt using a ring style connector for the sake of convenience. Once you have voltage, and a ground, you should have lockup function, if not then it is time to drop the pan and make sure the internal switches are hooked up and working.

When you test it for 12v on the "A" terminal, does it need to be running or just in the on position? Mine doesnt have any power going to it in the on position. Havent tested it with the truck running because i coulda swore i read somewhere it can be in the on position for the test.

 

[Greg Ducato]

When you test it for 12v on the "A" terminal, does it need to be running or just in the on position? Mine doesnt have any power going to it in the on position. Havent tested it with the truck running because i coulda swore i read somewhere it can be in the on position for the test.

If the system has a vaccum switch the vehicle may need to be running for power through the system but i may be wrong about that, someone correct me if I am. We always check them running just to be sure.

 

[Greg Ducato]

Ok i may have to try that. When you guys said to check for 12v at the terminal, is that plug a pain to pull off. Just dont wanna break it and be screwed. And to run a ground to d, do i have to splice a wire in?

The plug has a little tab that snaps onto the case connector to hold it in place, it can become brittle so only pull it out far enough to release it. You can splice into the wire already at the "D" position if it has one and run it to a ground, tape up the other end and tuck it into the loom if it isn't going to an ecm any more.

 

[dabomb6608]

It has the vaccum switch on the ds firewall. Guess i will test it when/if i get a chance after practice tonight or in auto class tomorrow.

 

[Deuling]

Just got home from being at work for 13 hours. I was the only one that could make it in besides brett(my boss). I worked till 3 then brett let me work on my truck. Fixed Timing (12* at idle, 8* advance with 15 HG of vacuum) Switched it to Non ported vacuum, and fixed manifold leaks and tranny leak. OMG its like driving a new truck. Breaks work 10 times better because of the vacuum fix, and its quiet as can be in the truck. It had that horrible manifold clicking sound before and i couldnt hear a thing driving.

Even filled her up with premium and a couple people came up to me and said my truck was awesome.

 

[Deuling]

The plug has a little tab that snaps onto the case connector to hold it in place, it can become brittle so only pull it out far enough to release it. You can splice into the wire already at the "D" position if it has one and run it to a ground, tape up the other end and tuck it into the loom if it isn't going to an ecm any more.

Ok so i checked, no 12v. I dont know what the brake thing is. Does it look like a 3" diameter round thing with rubber on it and 2 vac lines in the top?? if so i tried running ported vac to it and i grounded the little tab on the front of it, idk if thats what thats for or not though, i was kinda just b.s. ing it. Didnt change anything, still no 12v. Idk if it was even the right switch thing though lol. If anybody has a pic of it, put a link up or something. Thanks

 

[Greg Ducato]

Ok so i checked, no 12v. I dont know what the brake thing is. Does it look like a 3" diameter round thing with rubber on it and 2 vac lines in the top?? if so i tried running ported vac to it and i grounded the little tab on the front of it, idk if thats what thats for or not though, i was kinda just b.s. ing it. Didnt change anything, still no 12v. Idk if it was even the right switch thing though lol. If anybody has a pic of it, put a link up or something. Thanks

Your brake switch is under the dash and it rests against the brake pedal so that when you depress the pedal, the plunger in the switch moves and activates brake lights or disconnects circuit to the converter clutch/cancels cruise control setting. Some vehicles have two switches to cover all three functions.

 

[smier]

I've been following your other posts, if it's running signifigantly better you should have gained some mpg... I'd really go thru everything carefully, and I'll bet you can find more things wrong on a 25 year old truck. I was struggling with mine not running right for months. It ran ok, but not great. Keep after it, you'll get it. Glad your making some progress!!!

 

[Deuling]

Thanks man will do. Hopefully it starts pickin up now. It just drives better even. Once my carb kit comes in and i get the converter locking it should be a beast. I think it sat for a long time judging by the mud bee nests all over and the brand new tires that are cracked. Not leakin though. I think im gonna get some wide cooper cobras or a nice road tire set once winter is over. My van has the cobras and they are so smooth. Really coushony

 

[Deuling]

Your brake switch is under the dash and it rests against the brake pedal so that when you depress the pedal, the plunger in the switch moves and activates brake lights or disconnects circuit to the converter clutch/cancels cruise control setting. Some vehicles have two switches to cover all three functions.

oh somebody on here said it was by the brake booster lol. I was lookin high and low and that one thing was the only thing i saw haha. I think thats actually the pump for the defroster/heat panels to open up and close cuz the defroster is zip tied open at the moment lol. i couldnt figure it out when i got it, but defrosters are all i need for the winter. still heats the truck good so im not too worried. Thats last on my to do list. Theirs no 12v to the tranny but now (idk if its because of the vac line fixes) its locking up kinda half a$$ed in overdrive, but as soon as i touch the gas a little it downshifts. But i was doin 2000 on my tach at 65 so thats alot better then the 2400 it was doing.