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16168625 to 700R4 wiring for lock-up

I am doing a 4.3 TBI 700r4 swap into a 1970 Scout 800. I am using a harness and ECM out of a 93+ blazer, number 16168625. I am having a problem finding any info on the wiring for the transmission for the lock-up. All of the pinouts just say to electronic transmission but do not give you any info of which is which or what they do. Want I am trying to figure out is if I can wire the 700r4 to the pcm or do I have to wire it stand alone.

Bill USN-1

F.I. Moderator
I don't remember GM going backwards on the pcms.
The 8625 is a powertrain control for engine and trans and was used for the 4l60e and 4l80e.
I did a search of GM bins for the 8625 and did not find one listed with the 700r4.
That doesn't mean you can't make it work but it would take hacking of the code.
You have a couple options.
Just repin the connectors and run the 7747 ECM since it was designed for the TBI/700r4 or wire the 8625 for a manual and do the 700r4 work around. Either a toggle switch you flip for od or I think there are vacuum switches to control the lu function that guys use when they swap in just the 700r4 behind their stock motor.

Or go back and grab the 4l60e from the donor and bolt it in place of the 700r4 and run the pcm.

Bill USN-1

F.I. Moderator
Checking the 8625 code..there are provisions in the code to use the 700r4 trans.
It would take some trial and error but it could be made to work.
Here is a basic wiring conversion from the 7747 to the 8625. You should be able to look at the applicable 7747 wires used for the 700r4 and apply those to the 8625 wiring.

This one was from fast355:

pcm swap/tuning notes

8746/6965/7747/299 to 427 truck pcm (car showed, trucks very similar)

old pin----new pin-----color------------function

a1--------f6----------grn/wht-------fuel pump relay control
a3--------f16---------dk grn/yel-----charcoal canister purge solenoid
a4--------e1----------gry-------------egr control
a5--------e6----------brn/wht--------service engine soon light
a6--------e15---------pnk/blk---------ignition feed +12vdc
a7--------(1*)--------tan/blk---------tcc/shift light
a8--------f9----------orn------------serial datastream
a9--------a14---------wht/blk-------diagnostic test
a10-------f13---------brn------------vehicle speed signal
a11-------b3----------blk------------sensor ground
a12-------a1----------blk/wht-------ECM ground 1

b1--------e16---------orn------------battery +12vdc
b2--------b12---------tan/wht-------fuel pump signal
b3--------a5----------blk/red--------est ref low
b5--------a4----------ppl/wht-------est ref high
b7--------(3*)---------blk-------------knock sensor
b8--------e12---------lt blue--------a/c clutch signal
b10-------e5----------orn/blk--------park/neutral switch

c1--------(4*)-------blk/pnk---------a.I.r. Converter solenoid
c2--------e7---------brn-------------a.I.r. Port solenoid (diverter in trucks)
c3--------a7---------lt grn/blk------iac "b" low
c4--------a8---------lt grn/wht-----iac "b" high
c5--------a3---------lt blu/wht-----iac "a" high
c6--------a6---------lt blu/blk------iac "a" low
c7--------(5*)-------lt blu-----------high gear switch (in auto trans)
c8--------(6*)-------lt blu-----------power steering pressure switch
c9--------(7*)-------ppl/wht---------crank signal
c10-------b8---------yel--------------coolant temperature signal
c11-------b13--------lt grn----------map signal
c12-------b9---------tan-------------mat signal(8*)
c13-------a15--------dk blue--------tps signal
c14-------e14--------gry------------5 volt reference
c15/d14--a9---------drk grn--------injector "2" control
c16------e13--------orange----------battery (inputed in place of brake switch for tcc to function)

d1-------a2---------blk/wht--------ECM ground 2
d2-------b4---------ppl-------------map sensor ground
d4-------f11--------wht------------est signal
d5-------b2---------tan/blk--------est bypass
d6-------a12--------tan------------o2 sensor ground
d7-------a10--------ppl-------------02 sensor signal
d15/d16--a16-------dk blue---------injector "1" control

swap notes

(1*)= use e2 for a shift light on a manual transmission or e10 for the tcc on an automatic
(2*)= supported by the pcm if optioned in the prom on an unknown pin
(3*)= a.) wire like 1995 p30 step van, esc module output to b7
(3*)= b.) wire like 1995 c10 truck, bypass esc (blue to brown) and use late TBI/tpi 305/350 knock sensor
(4*)= air injection into converter not used on trucks, but pcm has several other un-used outputs (tuning valve, idle kicker)
(5*)= not used by pcm (I like to leave the small connector in place and pin in unused wires)
(6*)= supported by pcm if optioned in the prom on an unknown pin (1994-1995 2.2 s10 wiring diagram anyone?)
(7*)= not used by pcm, remove 3 amp "crank" fuse from fuse box and store in small connector)
(8*)= supported by the pcm, but functionality will need to be enabled in the prom

6965 only- will have a nc relay that the computer grounds to shut-off the a/c compressor when the engine is heavily loaded. The a/c will work either by removing the wire all-togather, or connecting it to pin e3 (a/c cut-off or cpi tuning valve output)

I would also like to mention that the orange serial data wire needs to be relocated from the top row, pin "e" to the lower row, pin "m". You will also need to scan the vehicle like a 1993-1995 g-series van, c-series truck, s-series blazer, etc with auto transmission.

Finally, this is a trick haulin@$$ taught me, if you have a wideband and are looking to get real-time afr put into the datastream, hook the 0-5 volt signal into pin b16 (linear egr pintle position feedback). With some adaption to the aldl definition being used to decode the reading, you can get an afr reading of 10-20:1 or so.
From what I had found, I do belive some of the 700r4's, or at least the 4l60 (non e) was used with this pcm, just cant seem to find a pinout that showed what I was looking for.

The donor vehicals are nolonger available. Every piece of the package came from a different one, the engine I got and was already pulled, the trans is from a 1989 blazer I picked up with a bad motor, the transfer is from a 1991 fullsized jimmy and the harness came from a blazer my cousin scrapped out and pulled intact for me, I think I got the pcm with it, but there is a chance it came from elsewhere also. Talk about a mutt creation asking for a headach :out:

so what I think I am seeing here is that e2 and e13 are where it needs to be connected, just need to figure out which goes where along with break switch input.

Looking at this diagram I don't think it will be that hard.

Break switch to a then playing with the other two to make them work the way I want.

Does this sound about right?
Ok, so took a second to slow down, been a busy day, and looked that over again.

Please give me input and/or corrections on this.

c16------e13--------orange----------battery (inputed in place of brake switch for tcc to function)

I am believing this to be 12v supplied to this point.

Then this:
a7--------(1*)--------tan/blk---------tcc/shift light

(1*)= use e2 for a shift light on a manual transmission or e10 for the tcc on an automatic

I see this as meaning to go from e10 to pin d on trans plug and f on the aldl connector.

Then you wire through the "nc" break switch and that goes to pin a on the trans.

That leaves:
c7--------(5*)-------lt blu-----------high gear switch (in auto trans)

(5*)= not used by pcm (I like to leave the small connector in place and pin in unused wires)

this would be connected to pin b of the trans, and from what I am able to find is I am thinking it should be connected to pin e11, but this is the unknown spot for me.


Bill USN-1

F.I. Moderator
For the tcc I use a standard relay with the 87/87a terminals.
Connect 12v thru pin 30 and it passes thru 87a.
Then connect gnd to 86 and the 12v output of the brake light switch to 85.
Then when you step on the brake it energizes the relay and removes the 12v from pin 87a. This will unlock the tcc when you hit the brake.

See the attached. It has a little more defined.