700R4 Manual Lockup Switch. 83' K5 Blazer. Pics.

buddyantunez1

Well-Known Member
Joined
Feb 26, 2013
Location
Raleigh, NC
Need some help on wiring up a manual lockup switch to regain torque converter lockup on my 83' K5. I don't feel like going through the factory wiring, since it's been through a few owners and most likely hacked up by now.

So obviously I have a non-ECM 700R4, and I just want to know the most simple and crude manual switch on the dash to lock the converter when cruising in 4th gear on highway drives.

I want this truck to be a beach/concert cruiser, and with 35's and 4.56's(CUCV 1 tons), I can only get to about 60 with 4th gear.

So does anyone have a simple answer or wiring diagram to get lockup working again? I already have an LED switch on the dash to use.


Couple pics of what I'm working with. Just installed the CUCV 60 and 14 bolt, rear shackle flip kit, and 35's.

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This looks like the simplest way to wire it up... Just want to confirm with someone before setting it up.

switch_wiring_1A.jpg
 
LOL I wish I could get to even 70 in 4th. Yes, overdrive works, just not lockup.

I can count out each gear, and in 4th, turning 2200 rpm I'm doing around 60 mph.

If i had the stock 3.73 gears, I could prob get close to 80, but not with the 4.56 CUCV's and only sporting 35's.
 
The converter still slips in 4th, so I need to get into lockup so I don't burn up the trans on extended highway rides to the beach and Walnut Creek.
 
Not running in lock up will NOT harm your trans. It just adds a little fuel mileage. Not being able to get over 60 ? Why?
 
did you put this PARTICULAR 700R in? you can mess one up bad / do funky things if the TV cable isn't setup correctly. summit sells a kit for cheap that allows this to happen- I wasn't aware that you can do it with factory wiring. you can then lockup in 3rd and 4th with a ground as shown above, super handy. tie it into you brake switch to open the circuit when you stop/slow down.

also, FWIW I can (and do) run 100mph (confirmed by GPS) with CUCV axles (stock 4.56:1) and 36"s = you got something bad going on. at 65mph Im only turning 1800 rpm. is this a diesel transmission???? they act all kinds of funny when put behind a a gas motor. its a simple swap of the governer springs to settle it back down.

o_O take it out of low range???
I drove around all weekend one time with mine in low... sounds dumb but with an auto, a happy high revving motor and loud stereo it happened.
 
buddyantunez1 said:
I can only get to about 60 with 4th gear./QUOTE]

buddyantunez1 said:
I can count out each gear, and in 4th, turning 2200 rpm I'm doing around 60 mph.
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You just need to let that engine scream. If you look at a chart (I think this one assumes 65mph with a 1:1 final drive) you will see that your overdrive seems to be working properly by bring your RPMs down from the upper 2000's.

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GPS's @ 62mph, in 4th gear, my truck was turning 2300 rpm or so. Yes, it COULD do more than that, but i'm not revving a stock 350 past that for long periods of time.
 
I got the truck with the motor(350 crate swapped), trans and tcase already in. I swapped the axles and went to 35's. I can count each gear and the truck grabs all 4 gears, just not lockup. Any way the tcase has been geared? I've confirmed the truck is in 2Hi.
 
buddyantunez1 said:
GPS's @ 62mph, in 4th gear, my truck was turning 2300 rpm or so. Yes, it COULD do more than that, but i'm not revving a stock 350 past that for long periods of time.
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it aint a ford dude, rev it up
 
A stock 350 will be fine cruising at higher rpms than that. Gas mileage won't be great, but it isn't going to hurt the engine. Stock small blocks through the 60s and 70s with 4 speed manuals or th350s (1:1 high gear) would cruise anywhere from 2700-3200 rpms going down the highway. It will be loud and it won't be great on gas, but it isn't going to destroy the engine or anything.
 
At 65mph, you should be turning 2100rpm with the converter locked. Give or take a little for a variance in tire size. That's perfect. Unlocked, could be 300-400 rpm more, depending on how good of shape the transmission and converter are in.

I actually have a 700R4 lockup setup, I think. You can have it if you want it. I always locked mine manually. It was second nature and I never forgot about it. I'd lock it in 3rd and let it shift locked. Helped me pick up speed with a lowly, naturally aspirated, 6.2 diesel.
 
I'd probably take you up on that!

I tested a manual switch on my 700r4 and no luck. Switched power to Pin A, ground to B and D, or either one, and nothing. So I'm sure something is up inside the trans or the converter needs to be replaced if I want lockup.

65mph at 2100 sounds perfect! Yes, I'm turning 2400 or so to attain that now. The water tamp creeps up to 210 or so, but it doesn't seem like it's hurting anything. I'd love to get 70mph out of it at 2300-2400 in lockup. That's perfect cruising speed from Raleigh to ILM in a lifted Blazer.
 
You could always drop a 160 degree thermostat in it. It'll run about 180 degrees or so. I'll go swing by the shop and make sure it's still where I think it is. I'll keep you posted.
 
Yeah, it has a 180 in it now. Going to a 160 with summer coming up, doesn't sound like a bad idea.

What all do you have? Converter, wiring inside the trans, ect?
 
The external lockup harness is all I have left, I think.
 
For a crude "harness" I've already tried putting a switched power source to Pin A, Grounded B, and Grounded D as well. Tried just grounding B, and Just grounding B, and none of them worked. I think it's an internal issue or the converter is not setup for lockup
 
I'd probably replace the internal wiring harness as well. If that doesn't work, then it's a non-lockup converter.
 
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