Trans Request Chrysler 42RE-48RE

'Microsquirt' Transmission Control development and support.

Moderators: jsmcortina, muythaibxr

Post Reply
midnite88
Helpful MS/Extra'er
Posts: 53
Joined: Fri Dec 10, 2010 10:33 am
Location: Ogden UT

Trans Request Chrysler 42RE-48RE

Post by midnite88 »

Hey everyone, wondering how hard it would be to add code to control Chrysler RE series transmissions. So for a run down on how it works, follow along.

The 42 through 48RE use the same valve body and control procedure. the transmissions only have Three solenoids, and Pressure sensor and a temp probe.
The 42RE was used in all light truck and SUV applications from 1993 through 2001ish This included Jeep Grand Cherokees, Dakotas and Durangos with V8s, Several of the early new gen Hemi's came with 48re's and all the diesel trucks from 93-2007 came with 47/48re's The 47 used cable TV, the 48 used a TV Motor

The Governor Pressure Solenoid is a variable force solenoid that controls up shifts
O/D Solenoid-Self explanatory, engages 4th gear overdrive
L/U Solenoid- Controls torque converter lockup, Due to the design of the V/B, the TCC L/U can only engage in 3rd and 4th gears. With V/B mods, you can accomplish 2nd
lock up. (I do it for the diesel guys quite often and they love it)
Governor Pressure Sensor - This guys is used for closed loop control of the governor pressure solenoid.
Temp Probe---Self explanatory.

How it all works.
1st gear -- Governor pressure solenoid is commanded wide open (Chrysler uses variable current, we have PWM) The factory computer looks to achieve 10psi or lower to get
into 1st gear.
2nd gear -- Governor pressure solenoid is commanded to go to 20ish psi (I say ish because I forget the exact value) to get into second gear. This is accomplished by slightly
closing the valve
3rd gear -- The Governor pressure solenoid is commanded closed or aprox 30psi to gain 3rd gear.
4th gear -- O/D Solenoid commanded on
L/U -- L/U solenoid commanded on

The closed loop control of the governor pressure solenoid is 3D based on vehicle speed and engine load. Factory looked at TPS. The governor pressure increases with vehicle speed just as old mechanical governors used too do. The kick down is controlled via a TV cable and the newer diesel run a TV pressure control motor which can be replaced with a standard cable setup. I believe the Governor Pressure Solenoid should be able to be PWM with the correct frequency. All solenoids are ground switched like most other setups. Depending on year of transmission, some had VR speed pickup, some had Hall Effect.

Ok thats all I can think of for now. Thanks guys!
88' F150 5.0 TFS Heads Comp XE258 Cam....Block now in two pieces
93 Foxbody...under construction Barra 4.0T
94 Jeep ZJ Bone Stock
97 Jeep ZJ Bone Stock
08 Buell XB12R, custom exhaust, soon to be turbo'd and MS3'd :yeah!:
Matt Cramer
Super MS/Extra'er
Posts: 17499
Joined: Thu Apr 16, 2009 8:08 pm

Re: Trans Request Chrysler 42RE-48RE

Post by Matt Cramer »

Had a customer calling me requesting support for this as well. Looks like a totally different form of shift logic.
Matt Cramer -1966 Dodge Dart slant six running on MS3X
midnite88
Helpful MS/Extra'er
Posts: 53
Joined: Fri Dec 10, 2010 10:33 am
Location: Ogden UT

Re: Trans Request Chrysler 42RE-48RE

Post by midnite88 »

Matt, that customer was me, I threw it up here as well as asked you haha.
88' F150 5.0 TFS Heads Comp XE258 Cam....Block now in two pieces
93 Foxbody...under construction Barra 4.0T
94 Jeep ZJ Bone Stock
97 Jeep ZJ Bone Stock
08 Buell XB12R, custom exhaust, soon to be turbo'd and MS3'd :yeah!:
steveh66
MS/Extra Newbie
Posts: 27
Joined: Fri Jun 29, 2012 5:29 pm
Location: Calgary AB Canada

Re: Trans Request Chrysler 42RE-48RE

Post by steveh66 »

I doing the the same thing you are wanting to do with a 48RE. I've got the transmission and building up the controls and have research the logic to what it does.

Everything you stated is correct but I'll build upon the governor control methodology

What the electronic governor does is it produces one PSI of governor pressure per MPH. The governor in this case works just like a manual hydraulic governor and acts upon the throttle pressure to control shift timing. That's what you're probably seeing.

Electronic governor does some tricks as it increases pressure high when it's in overdrive gear to prevent a downshift which would be the same as coming out of overdrive and into second. This is because Third gear is engaged and on top of third gear overdrive is engaged. Any hydraulic action for the governor would take it out of third gear with the overdrive engaged and then put it into second gear and that would block the over drive so you do a double down shift.

Overall you should be able to control the governor pressure just the same as all the other transmission that her controlled by a mega squirt.
Matt Cramer
Super MS/Extra'er
Posts: 17499
Joined: Thu Apr 16, 2009 8:08 pm

Re: Trans Request Chrysler 42RE-48RE

Post by Matt Cramer »

Had another request come in. This one may be a bit of an oddball, but it also would appear we'd own the market for a standalone controller. There's no other competition for this.
Matt Cramer -1966 Dodge Dart slant six running on MS3X
prof315
Super MS/Extra'er
Posts: 3760
Joined: Sun Jan 18, 2009 3:13 am
Location: Melbourne, FL

Re: Trans Request Chrysler 42RE-48RE

Post by prof315 »

Matt Cramer wrote:Had another request come in. This one may be a bit of an oddball, but it also would appear we'd own the market for a standalone controller. There's no other competition for this.

I have also had a couple of people ask me about these and the 545RFE which is a 5 speed auto in the same family. As Matt says nobody has a controller for this family of transmissions
Linfert Performance/321 Motorsports
SCCA 2019 SM National Champion Crew Chief
SCCA 2023 FP National Champion Tuner/electrical engineer
100s of MS systems built installed and tuned
Support the developers!
guhfluh
Helpful MS/Extra'er
Posts: 102
Joined: Thu Apr 26, 2007 12:07 pm
Location: Louisiana

Re: Trans Request Chrysler 42RE-48RE

Post by guhfluh »

Matt Cramer wrote:Had another request come in. This one may be a bit of an oddball, but it also would appear we'd own the market for a standalone controller. There's no other competition for this.
There was a controller offered by someone for the diesel market. It was possibly Suncoast or AFE? It wasn't cheap and I didn't ever have to have one, so I never pursued it. It is a simple control, as it's really a hydraulic control from 1-3, but since you CAN manipulate governor pressure, you have a little more control there. The overdrive and lockup are controlled by manual switches most of the time with people who don't like the factory control, but I like the ability of automatic programming control that could be adapted to another vehicle and/or engine.
prof315 wrote:
Matt Cramer wrote:Had another request come in. This one may be a bit of an oddball, but it also would appear we'd own the market for a standalone controller. There's no other competition for this.

I have also had a couple of people ask me about these and the 545RFE which is a 5 speed auto in the same family. As Matt says nobody has a controller for this family of transmissions
I do not believe you are correct that the RFE line of transmissions is the same family. The "Fully Electronic"(FE) line of transmissions are "clutch to clutch" type of transmissions, similar to the front wheel drive 40/41/42TE or A604? transmissions where every clutch and band is PWM solenoid applied and one has to be released while the other is applied for a shift.

Support for the RE line of transmissions would be great and should be simple. They are great transmissions based off the TF727 and 904 of old, with overdrive and lockup converter additions and there is a huge aftermarket for all the soft and hard parts of them to build anything from mild to wild, gas to diesel.
'99 Neon, NGC 2.4L, MS2, P&H board, EGT board, turbo, etc... MS2extra3.1.1 currently
Matt Cramer
Super MS/Extra'er
Posts: 17499
Joined: Thu Apr 16, 2009 8:08 pm

Re: Trans Request Chrysler 42RE-48RE

Post by Matt Cramer »

Was looking over the description of this transmission in Alldata, and it looks as if there may have been a missed opportunity here. Had Chrysler designed the valve body so the overdrive could engage in 1st gear, this would have been a 5 speed transmission, with a gear halfway between the existing 1st and 2nd. Engaging the overdrive in 2nd would be the same ratio as 3rd. But there is a hydraulic interlock that only lets the overdrive engage in 3rd.
Matt Cramer -1966 Dodge Dart slant six running on MS3X
guhfluh
Helpful MS/Extra'er
Posts: 102
Joined: Thu Apr 26, 2007 12:07 pm
Location: Louisiana

Re: Trans Request Chrysler 42RE-48RE

Post by guhfluh »

Matt, that may be how Chrysler achieves the dual ratio 2nd gear of the 545RFE transmissions, one for upshift and one for downshift passing. I have never looked into it that closely.
'99 Neon, NGC 2.4L, MS2, P&H board, EGT board, turbo, etc... MS2extra3.1.1 currently
kaputnik
MS/Extra Newbie
Posts: 6
Joined: Thu May 06, 2010 3:45 am
Location: Germany

Re: Trans Request Chrysler 42RE-48RE

Post by kaputnik »

Maybe it is of interest, there are 2 SAE Papers (1999-01-1260 [0] and 1999-01-0755 [1]) available about the 45RFE, which is architectural identical to the 545RFE and i think also to 68RFE.

I read the 1999-01-0755 Paper and they explain quite in deep how to control it, including pulswidth for pressure control pwm, plots of gear changing with all kinds of signals in it and so on. They explain alot of the control strategy, for example the line pressure target is around the point of barely no slippage using the 2 speed sensors and so on. It for sure more in deep than the Chrysler FSM.

[0] http://papers.sae.org/1999-01-1260/
[1] http://papers.sae.org/1999-01-0755/
HEMI 5.7 + FAST92mm + MS3 + MS3X
gfolsom
MS/Extra Newbie
Posts: 15
Joined: Thu Mar 01, 2012 4:21 pm

Re: Trans Request Chrysler 42RE-48RE

Post by gfolsom »

Naive question, are you working with the Microsquirt box to add the Mopar control like the existing GM control or with the GPIO board? I saw the adds for the microsquirt work on the main forum list and then thought I read this effort was GPIO based somewhere.
Matt Cramer
Super MS/Extra'er
Posts: 17499
Joined: Thu Apr 16, 2009 8:08 pm

Re: Trans Request Chrysler 42RE-48RE

Post by Matt Cramer »

gfolsom wrote:Naive question, are you working with the Microsquirt box to add the Mopar control like the existing GM control or with the GPIO board? I saw the adds for the microsquirt work on the main forum list and then thought I read this effort was GPIO based somewhere.
If this is implemented, it would be intended for the MicroSquirt but cross over to the GPIO.
Matt Cramer -1966 Dodge Dart slant six running on MS3X
apalrd
MS/Extra Newbie
Posts: 14
Joined: Sun Sep 13, 2015 7:54 pm
Location: Flint, Michigan

Re: Trans Request Chrysler 42RE-48RE

Post by apalrd »

guhfluh wrote:Matt, that may be how Chrysler achieves the dual ratio 2nd gear of the 545RFE transmissions, one for upshift and one for downshift passing. I have never looked into it that closely.
The 45RFE,545RFE,65RFE use a gearset and controls derived from 42TE, completely unrelated to the 48RH. The gearset in 42TE ties the 1-2 ratio step to the R ratio, and the RWD platforms needed a steeper R ratio without a large 1-2 step. The RFE adds an extra planetary and clutch into the 4-speed gearset, which essentially splits the 24 brake into two different points (2C and 4C).

The 66RFE and 68RFE (behind the 6.4L Big Gas and 6.7L Cummins truck engines respectively) has a modified gearset (two connections are swapped and the tooth counts are different), which spreads out all 6 gears and they shift as sequential 6 speeds. However, the R ratio is much higher (~4.5 vs ~3).

You don't want to engage overdrive in 1 to get an intermediate ratio, because then the 1-prime to 2 shift requires doing 2 shifts together (shifting the main box 1-2 and shifting the overdrive OD-Direct). Any mistake in timing could land you in 1 or 2-prime for a period of time.
kingcrunch
Helpful MS/Extra'er
Posts: 49
Joined: Mon Jun 09, 2014 5:03 am

Re: Trans Request Chrysler 42RE-48RE

Post by kingcrunch »

Just for the record:

I am interested in either config (42-48re and 545rfe) too!
midnite88
Helpful MS/Extra'er
Posts: 53
Joined: Fri Dec 10, 2010 10:33 am
Location: Ogden UT

Re: Trans Request Chrysler 42RE-48RE

Post by midnite88 »

Havent been on in a while, still interested in this as now I might be looking to do a 46RE behind a 1954 241 Red Ram hemi with a couple hair driers just for fun. 8) Still thinking the Gov solenoid could be controlled via PWM. My only drawback is...I dont know code! There is another stand alone for the RE line called the Anteater by Firepunk Diesel, I've checked out the system and downloaded the tuning software....less than amused to say the least. Very, very basic controls, but the one leg up they have is it does work. How well I dont know.
88' F150 5.0 TFS Heads Comp XE258 Cam....Block now in two pieces
93 Foxbody...under construction Barra 4.0T
94 Jeep ZJ Bone Stock
97 Jeep ZJ Bone Stock
08 Buell XB12R, custom exhaust, soon to be turbo'd and MS3'd :yeah!:
guhfluh
Helpful MS/Extra'er
Posts: 102
Joined: Thu Apr 26, 2007 12:07 pm
Location: Louisiana

Re: Trans Request Chrysler 42RE-48RE

Post by guhfluh »

midnite88 wrote:Havent been on in a while, still interested in this as now I might be looking to do a 46RE behind a 1954 241 Red Ram hemi with a couple hair driers just for fun. 8) Still thinking the Gov solenoid could be controlled via PWM. My only drawback is...I dont know code! There is another stand alone for the RE line called the Anteater by Firepunk Diesel, I've checked out the system and downloaded the tuning software....less than amused to say the least. Very, very basic controls, but the one leg up they have is it does work. How well I dont know.
Another thread bump....

I'm still interested in this. Currently there are still only 3 aftermarket control options for the 42 through 48re transmissions, two at ~$800 and one at ~$1300 with a while new valve body required. There is still no factory TCM tuning offered. I'd love to have a cheaper alternative.

One maybe "new" thing to note is there is a need to vary the governor pressure control maps with fluid temperature, as the viscosity change seems to mess with the shift points quite a bit. It may also be due to fluid leakage rates and/or tolerance changes in the VB, but it's just something to note that would need to be added to the code.
'99 Neon, NGC 2.4L, MS2, P&H board, EGT board, turbo, etc... MS2extra3.1.1 currently
madman4
Helpful MS/Extra'er
Posts: 42
Joined: Wed Feb 23, 2005 7:27 am

Re: Trans Request Chrysler 42RE-48RE

Post by madman4 »

Ouch, 6 years ...

Is the 42-48 RE project down ?
Have a Right Foot ???

USE IT !!!
ryan99alero
MS/Extra Newbie
Posts: 1
Joined: Sun Jul 09, 2023 12:53 am

Re: Trans Request Chrysler 42RE-48RE

Post by ryan99alero »

I'd be down as well for a transmission controller for the Mopar world that always seems to get left behind. I've been wanting to build either a 408 stroker or just build a boosted 360. Then go with either a MegaSquirt, Holley Terminator X or a HalTech Elite 2500. I believe I read somewhere the Holley Terminator can control the 46RE. I'm wanting to integrate this all into something like Automative Grade Linux or Android Auto. I plan on putting like a 17" display where the Stereo, HVAC, Drink tray and so on are. Also will replace the instrument cluster with a digital panel as well. AGL can control both panels.
96 Dodge Ram Laramie
318 4x4 Extended Cab
INDY/IMM Ported heads
SCT Tuner
Comp Cam: XR264HR-14
Post Reply