Out with the JTEC, in with....

[34blazer]

So since my studies into code has stalled, and my career/family life isn't very flexible, I abandoned any hope of tuning the JTEC currently in my '97 Ram SS/T. I've had the week off for Christmas and started doing some research into some GM based PCM options for the truck. The 0411 would be an ideal swap but its hard to find anything in the boneyards over here and its probably outside my budget for another couple of years. I thought about MS but that would only take care of the engine, not the trans. Started looking through the dodge forums to figure out how difficult it would be to find a way to control the 46RE, found out it may be surprisingly easy. Apparently the those are 518 series(727 with OD?) and don't have a lot of electronics. So far I'm finding there is a pressure solenoid/transducer; 3-4 shift solenoid, and OD solenoid. There is also a common modification to convert the pressure solenoid to a GM EPC, since the mopar part isn't self cleaning and has a tendancy to "flood" causing a "no shift" condition.

That got me thinking, what if I find a '7427(?) and use $OD? It may be OBDI but I don't care, smog exempt!

Will $OD be compatible with the multi port EFI?

Trans controls, it seems like adapting that to the 46RE shouldn't be an issue?

Im not totally sure, so Ill ask a stupid question, but ill be able to use my Osty 2.0?


I have a PDF version of the factory service manual, I wish it had pinouts for the JTEC consolidated on one page though, anyone have some?

My plan is to build a discrete adapter harness using a bricked or busted JTEC, keep all the connections contained within the JTEC shell and install the GM ECM inside the cab. This way it appears to be OEM. Looks like all the gauges will work, and the ABS is totally separate, iirc it doesn't even have a BCM. Anyone have a busted JTEC they wanna get rid of?

Soooo, opinions? Thanks in advance!

[34blazer]

Just grabbed the $OD xdf, holy crap!

[dave w]

The '7427 PCM can run MPFI. See attached document.

I'm wondering if maybe the Dodge computer can be tricked into operating the transmission with only the necessary inputs (Ign, Bat +, Bat -, VSS, TPS and ???) from the '7427 PCM.

My most recent experience '7427 / MPFI system conversion is with a Vortec 5.7 liter.

dave w

[34blazer]

Yeah I believe so, there are people using MS piggy-backed to a Mopar JTEC or factory JTEC to retain trans controls. I want to use trans controls since the shift points are low, like 4800 iirc. I figured the 7427 would be able to control the 46RE since it uses a governor pressure solenoid and a 3-4 shift solenoid. If I could disable the 1-2/2-3(?) shift in $OD I think it may just work. But im no transmission pro.

*edit* Thanks for the doc as well!!!

[34blazer]

Im confident Ill be able to figure out the engine side of the set-up. Trans controls I need help on. Open to any advice!

[delcowizzid]

you could use a 1227165 ecu and the aussie $12P custom code http://pcmhacking.net/forums/viewtopic.php?f=27&t=356 .it has 4 user definable outputs that can be triggered by all manor of values .they operate at 32hz and are pwm outputs so can set to 0-100 D/C im sure they could be setup to control pressure and the 3-4 shift and tcc lock if all the other shifts are done by the gearbag itself.the xdf and adx are FULLY defined with every setting availiable.its also real time tunable down the aldl with an FTDI chipset based aldl cable and an NVram inside the ecu

[34blazer]

Only problem with that is the governor pressure control and feedback circuits. I suppose part of $OD could be patched?

That would be awesome if I could use 12P!

I found a 46RE service manual, and a 4L60E service manual. If the line pressures are similar, tuning shouldn't be too much a problem.

[34blazer]

Looks like i'll have to use the part of the logic the energizes 2/3 solenoid to operate the 46RE's 3/4 solenoid in conjunction with the manual OD switch in the dash of the Ram.

Now i'll have to figure out how the rest of the shift logic works within $OD, and figure out how its going to act since it doesn't have to actuate a 1/2 solenoid. Maybe a resistor to simulate a solenoid in the circuit and try to match up to the shift patterns, i.e. TPS vs. speed vs. load? Line pressures and feedback circuits seem to be identical.

Am I on the right track?

[34blazer]

List of vehicles with the '7427?

[dave w]

List of vehicles with the '7427?

1995 GM Full Size Pickups, Suburbans and Tahoe's with V8 engines (5.0, 5.7, & 7.4) using either 4L80E or 4L60E.

dave w

[34blazer]

1995 GM Full Size Pickups, Suburbans and Tahoe's with V8 engines (5.0, 5.7, & 7.4) using either 4L80E or 4L60E.

dave w

Wow, that's slim pickins for that ECM. I hope I can find one around here LOL.

[34blazer]

Looks like Im on my own with this swap too.

Got some TO's to study!

[JeepsAndGuns]

The 7427 came in more than that. It was in 94-95 model trucks (fullsize and compact) fullsize vans and astro vans too. If it comes from a astro or a S10/S10 blazer, it will have a V6 memcal and you will need to locate a V8 one.
You could also use a 16168625 from 93 models. Its basicly the same and will run $0D just fine. (I have done it)
Ebay is usally flooded with these PCM's if you can not find one local. Also, I may have a extra one with a V8 memcal if you still have trouble finding one. Or if you can only find a V6 one, I have a couple spare V8 memcals.

[34blazer]

Since the current dizzy doubles as the cam sensor, is there a swappable dizzy I can use with a traditional reluctor?

Thanks!

[dave w]

Since the current dizzy doubles as the cam sensor, is there a swappable dizzy I can use with a traditional reluctor?

Thanks!

The '7427 does not need a cam position sensor. The '7427 needs distributor reference pulses, one per cylinder. The '7427 distributor reference pulse are sent to the 8 pin ignition module. The '7427 use a 40 pulses per driveshaft revolution for the VSS input to control an "E" Transmission.

Not sure this post helps?

dave w