Recently we have been dabbling with converting the (yuck) OBD"1.5 cars to earlier ECM's. Generally have been using the '7727 because it is an easy swap with the waterproof case (I know it's the '7730's brother) and have a current project and would like to try the '7730 (have several of them laying around). Very successful, but have a few questions.

Done both ways, hard wired into the harness and hacking up a 93-95 PCM to make an adapter that allows a "plug and play" situation for easy install and also having the ability to go back to the stock PCM to track down issues.

First, I was wondering, does the code mask have an affect on the pinout diagram? Most cars are DIS and have been using $a1 since it was already setup for no distributor. I want to use the '7730 in the same situation (cams as a DIS package in FWD cars using $a1) and wasn't sure if the pinouts change between years/masks. Using Alldata most of the wiring and pinouts is obvious, but have found a few small discrepancies. Mainly in the wire color and/or the GM designation (ie "430" for ground etc). Seems as though the experimentation has worked in most cases.

So this leads to the second question : The A/C function on the newer cars is different than the older ones. I have a '93 car on the lift now and did a '7727 swap on it, everything works great except for the A/C. The request is working according to datalogs, but with the multiple pressure sensors and having the additional evap temp sensor is confusing me. I really don't want to rig it and have it function like stock (ie, no "hot-wiring" the relays), but how would I go about it? I am sure anyone running a newer motor on an older ECM would have the same problem - like an LSx running off an older ECM.

And finally: From what I understand the 4l60e and 4t60e have a different way of shifting. We have been able to use the '9396 ECM from a 3.4 DOHC (came with a 4t60e) on the FWD cars, but am leery about trying it on a 94 or 95 4l60e (already have used it on the non-e 4l60 since it's really a 700r4, no problems). The 94 and 95 are also two very differnt beasts in the fact that the 95 got an additional trans temp signal - 17 wires vs 16 on the 94.

I am sure with enough time and research this can all be figured out, but though perhaps the best place to go would be where all the PROM guru's hang out!

Thanks in advance,

-john

 

Well, I see the differences in the masks and pinouts after studying the diagrams

This ECM is going in a Fiero with a 3400 and a '95 3.4 Camaro/Firebird wiring harness, quite the hoshposh of parts eh?

Here's the way I am wiring it in case anybody else wants to do something like this...

pin# from the '95/pin # from the $a1 '7730
a1/b6
a2/c9
a3/??? (A/C evap temp signal, not on $a1 '7730)
a5/f14
a6/e13
a8/a11
a15/f6
a17/b5
a18/??? (TCC brake switch not on $a1 '7730)
a22/d15
a29/f15
a30/f13
a31/e16

b2/e8
b3/??? (secondary air pump relay not on $a1 7730)
b4/f7
b6/f1
b7/e7
b11/f9 (for digital EGR only)
b12/f4 (for digital EGR only)
b13/f5 (for digital EGR only)
b14/b1
b15/c16
b16/d6
b19/a9
b20/e15 (dual o2 sensors on '95)
b21/e14 (dual 02 sensors on '95)
b22/e14 (dual o2 sensors on '95)
b23/e15 (dual o2 sensors on '95)
b24/e5
b25/e6
b26/e4
b27/e3
b28/b11
b29/b9
b30/b10
b31/a4 and/or a5 ('95 harness has one 5v ref)
b32/d7

c1/a12
c3/a6
c9/e12
c11/d16
('95 is SFI have to wire the injectors together for MPFI)
c12/c12
c13/c11
c14/c12
c15/c11
c16/c12
c32/c11

c17/d1
c18/??? (no cam sensor on $a1 '7730)
c20/f9
c21/??? (no 24x crank signal on the '7730)
c25/??? (no cam sensor on $a1 '7730)
c27/c8
c28/c7
c29/f16
c30/d8
c31/d9
c32/c11



Still need to study the diagrams more to understand the A/C situation, but does anybody have info on the transmission thoughts?

 

as i understand it, no 730,727 or 749 can control a E trans. this is why guys are getting into the $0 code in the 93ish tbi truck ecm's. 427s maybe? anyways, those can be switched to port injection and run the e trans i believe. just not that hacked up yet.

no need to run A1 for the DIS. so far i've used $8D and code59 with a DIS from a northstart. just gotta change a few numbers in the bin. if you go with either of those i can tell the addresses in the code' plus its on here. just don't know it off the top of my head.


as for the A/C evap temp signal. what kinda signal is it? if its a on off type of temp signal it wouldn't be hard to wire in. or check into the old 60s type of AC setups, they have a temp type that wraps around the low side line and should be an on off that can run a normal relay. but if its the newer style that changes resistance based on temp, then your not going to be able to wire that into the 730s as is. you may be able to rewrite the code to look at it, as if it was a coolant or iat sensor, that is if there's a unused imput that can handle that kinda sensor. but either of those i don't know. if it was me, i'd ditch the evap temp and switch the compressor to a ver displacment type,(thats what i did from a 95 s10) or use the stock one with a cycle switch on the low side.

 

Right. I understand that the '7730 and '7727 cannot run an e trans, sorry about any confusion. I would like to know if the '9396 ECM can run a 4L60e since it does shift a 4T60e, and if not, what are the differences. I am having trouble wrapping my head around the whole shift selenoid/TTC control differences, and the internal trans temp sensor etc.

Thanks for the input for the A/C. There is a way to use the extra pressure signal to trip the compressor relay, but again, just not grasping the idea. Has something to do with grounding the A/C relay through it so if the pressure gets too low, or high, the compressor will kick off. My friend has the Alldata for a few of these cars, but haven't looked at the chassis electrical to see what signals are going where.

 

The "7427" TBI/CPI/MPFI 2.2 ECM can and HAS run a PFI 3.4 and 4L60E with the DIS module. I jumpered the current sense resistors and put it in PFI mode. I had it in a 1987 S15 Jimmy.. 95 Camaro 3.4/4L60e.. Converted the trans to 4x4 and installed the speed sensor from a later 4x4 into the transfer case. It was ALOT of work but ran really well with the 3400 aluminum heads and Crane 272 came.









I initially ran the 3.4 with the 2.8s TBI and the 3.4s DIS....I had swap the fuel pressure regulator and injectors from a 305 onto the 3.4 to get it enough fuel.. It was a tad lean trying to run on the 2.8s 36# injectors and 8 psi fuel pressure.

http://www.youtube.com/watch?v=gdQENVYISPs

 

'7427, not the '7727 though, right?

Hmm, I would like to learn more about this '7427 now.

I know the DIS module can be run by just about any GM ECM since they all have the same bypass, high and low signal. I have been using $a1 simply because it's the stock mask for the FWD DIS cars that have the reluctor pickup for #1 60 degrees advanced.

8psi?!?! LOL, I'm guessing you kept the carb fuel pump?

 

NOPE...It was a TBI 2.8 from the factory...8 psi is what the stock setting was on the regulator...DESPITE THE FACTORY SPEC OF 9-12 PSI... No wonder it ran like crap on the stock settings.

 

huh? what was that John?

 

Stalker!