700r4 help!

nitrouspete

nitrouspete

Forum Member
so were building a 1985 k5 blazer in my shop right now. its got a 700r4. ive been looking for a replacement wiring harness for the TCC 4 prong connector but have came up empty handed. i need it to function just like factory. its just a daily driver truck nothing special.

thanks in advance for anyone's help! REP WILL BE GIVEN!
 
i did see the plug is available, but i mean where the wires run to and the switch i do not have. i was wondering if they offered an entire kit.

thanks gearbox and tooslo!
 
i know i can get the plug, im more talking about some sort of factory piece that will make the trans tcc work just like factory.
 
Bowtie overdrives has a tcc lockup kit as I'm sure other's do as well. I want to say that you can hard wire it up as well. One of the wires gets it's ground from the ecm, if it had it, another is a 12v switched input which if I recall would make it lock up in all but 1st. In factory form there is an internal pressure switch that tells it that it is in high gear to lock up.

Supposedly the shop in CA that built my last one did something internally to make it lock without any electronics.

Rich, please correct me if I'm wrong. It's been a very long time since I looked into it for my own.
 
Ok, so here's what I found; looks like the tan/black goes to the aldl connector, light blue is input from the ecm (ground), and the purple is to the brake switch which would be the 12v that would get cut with the brake depressed.

Once again, correct me if I'm looking at this incorrectly.

700R4 Wiring0001.jpg
 
its all good man. i found a harness yesterday after work at a junkyard, and im hoping that i can use it and the routing i found it in. haha
 
These early versions of 700r4's (before 1987) were somewhat of a pain in the ass. (besides being very light duty)
The harness not only sends power down to the TCC solenoid, but it also sends ground signals back to the ecm for 3rd and 4th
The electric portions were some what unreliable. When they failed, you would loose tcc apply. If this happens and you jump on the freeway for several hours in 4th you melt the low planetary.
When I overhaul one of these units, I drop a check ball in the snout of the TCC solenoid. This disables the electrical control of the TCC apply, and now the tcc is applied strictly off the tcc shift valve in the valve body. Leaving all of the electrical components in place keeps the ecm from throwing dtc's. This prevents all possible failures from the electrical side of the tcc apply.
Bottom line is this=Make sure your TCC applies/works properly when your done.
 
Detroit Gearbox said:
These early versions of 700r4's (before 1987) were somewhat of a pain in the ass. (besides being very light duty)
The harness not only sends power down to the TCC solenoid, but it also sends ground signals back to the ecm for 3rd and 4th
The electric portions were some what unreliable. When they failed, you would loose tcc apply. If this happens and you jump on the freeway for several hours in 4th you melt the low planetary.
When I overhaul one of these units, I drop a check ball in the snout of the TCC solenoid. This disables the electrical control of the TCC apply, and now the tcc is applied strictly off the tcc shift valve in the valve body. Leaving all of the electrical components in place keeps the ecm from throwing dtc's. This prevents all possible failures from the electrical side of the tcc apply.
Bottom line is this=Make sure your TCC applies/works properly when your done.
Click to expand...

If it dosent work, sounds like ill be bringing you a valve body..haha
 
If you go electric lockup make sure you have the right brake switch. IIRC You need one with a normally closed pin in addition to the normally open pin. NC opens the circuit and unlocks TCC. The NO side works the brake lights.

Sent from my DROID BIONIC using Tapatalk
 
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