Trans shifting problems
Post Fiend
Joined: Dec 2009
Posts: 15,505
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From: Livoina,La
Neutral safety switch, Transmission range switch (TRS), and Manual Lever postion switch (MLPS) is all the same thing it's just called different things depending on where you go to get it
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From: Spanaway
I'm thinking you (Fixitman) may be right. I snipped the wires going to the #1 & #2 shift solinoids. I then hooked up a couple of toggle switchs to the trans side of the wires so that I could act like the computer and contol the shifting. The trans shifts perfect.....now I am sure that it is an electrical problem. Since I have ohmed the harness and changed all the sensors then the trans control computer is all that is left. I still wonder about one thing tho'......gas engine vehicles have the trans control within the engine ECU. The diesels have it seperate. Most E4OD's have a turbine speed sensor for the input speed. Diesel does not. So does the ECU communicate with the TCC and get the input speed from the crank sensor.....Hmmmm?
Last edited by autotech2; Sep 7, 2011 at 09:50 PM. Reason: Direct to fixitman
Frmr Ford Trans Engr
Joined: Aug 1999
Posts: 24,698
Likes: 2,620
From: SE Florida
No E4OD has a turbine speed sensor, gas or diesel. That didn't start until the 4R100.
Diesels only had a separate control module when mated to the diesel IDI engine. That was because the diesel IDI was a mechanical engine, not electronic. There was no engine computer. Starting with the 95 Powerstroke engine the E4OD controller was in the same control module as the engine.
That control module (called the PCM) controls all the solenoids including the shift solenoids and the TCC.
You have this posted in the Powerstroke forum, but it looks like you have a '92. The '92 does have a separate TCM because the engine does not have a computer.
Diesels only had a separate control module when mated to the diesel IDI engine. That was because the diesel IDI was a mechanical engine, not electronic. There was no engine computer. Starting with the 95 Powerstroke engine the E4OD controller was in the same control module as the engine.
That control module (called the PCM) controls all the solenoids including the shift solenoids and the TCC.
You have this posted in the Powerstroke forum, but it looks like you have a '92. The '92 does have a separate TCM because the engine does not have a computer.
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From: Spanaway
No E4OD has a turbine speed sensor, gas or diesel. That didn't start until the 4R100.
Diesels only had a separate control module when mated to the diesel IDI engine. That was because the diesel IDI was a mechanical engine, not electronic. There was no engine computer. Starting with the 95 Powerstroke engine the E4OD controller was in the same control module as the engine.
That control module (called the PCM) controls all the solenoids including the shift solenoids and the TCC.
You have this posted in the Powerstroke forum, but it looks like you have a '92. The '92 does have a separate TCM because the engine does not have a computer.
Diesels only had a separate control module when mated to the diesel IDI engine. That was because the diesel IDI was a mechanical engine, not electronic. There was no engine computer. Starting with the 95 Powerstroke engine the E4OD controller was in the same control module as the engine.
That control module (called the PCM) controls all the solenoids including the shift solenoids and the TCC.
You have this posted in the Powerstroke forum, but it looks like you have a '92. The '92 does have a separate TCM because the engine does not have a computer.
I have three diesel trucks a 1992 F250 4X4 Dually with an auto 6.3 no turbo. A 1994 F250 2WD with a 7.3 Turbo and a 5speed trans. And a 1996 F250 4X4 7.3 Turbo Non dual wheels. (actually 4 if you count my 1991 UD Rollback Tow truck inline six with a 5 speed.)
I HAVE BEEN AN AUTO MECHANIC SINCE 1979 AND HAVE HAD MY OWN SHOP FOR THE LAST 8 YEARS. ASE MASTERTECH WITH L1. 3 YEARS AGO I BOUGHT 50% OF A CAR LOT THAT DEALS IN MOSTLY 5TH WHEEL TRAILERS AND OTHER RV'S HENCE THE PULLING TRUCKS. I HAVE A PRETTY FAIR UNDERSTANDING OF DIESEL ENGINES AND SYSTEMS BUT HAVE NEVER HAD CLASSES AND IT IS SOMEWHAT NEW TO ME.
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From: Spanaway
YOU SOUND LIKE THE GURU I'VE BEEN LOOKING FOR. QUESTION, WHEN I HOOKED UP THE SWITCHES AND WENT FOR THE TEST DRIVE WHEN I WAS IN 4TH GEAR AT 2500 RPM I WAS ONLY GOING 45 MPH. DRIVING AT 30 MPH IN 3RD GEAR IT ACTES LIKE IT POPPED INTO N. AFTER MESSING WITH THE TRANSFER CASE SHIFTER I WAS ABLE TO GO AGAIN. QUESTION IS......DO YOU THINK THAT MAYBE THE TRANSFER CASE CAN BE THE WHOLE PROBLEM? DOES THE SENSORS IN IT GIVE THE PCM REQUIRED INPUT TO SHIFT? I'M PULLING IT IN THE AM AND GOING TO DISMANTLE IT AND DONT WANT TO BUY A PCM IF I DON'T HAVE TO.
Last edited by autotech2; Sep 10, 2011 at 09:07 AM. Reason: Too clarify
Cargo Master
Joined: Jul 2010
Posts: 3,014
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I'm going to let Mr. Kovalsky take this one, lol.
Edit: I also would politely suggest that you disengage your caps lock before making any further posts.
Edit: I also would politely suggest that you disengage your caps lock before making any further posts.
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Frmr Ford Trans Engr
Joined: Aug 1999
Posts: 24,698
Likes: 2,620
From: SE Florida
The only input to the PCM from the transfer case is the switch that tells the PCM if the transfer case is in 4x4 low. If it were to tell the PCM it is in 4x4 low when it is not the trans will shift to a higher gear much too soon. It cannot make it go to neutral.
PCM failures do happen, but they are very, very rare.
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From: Spanaway
The one in the firewall is the PCM. That controls the engine and transmission. The one on the wheelwell is the injector driver module. The PCM tells that what to send to the injectors.
The only input to the PCM from the transfer case is the switch that tells the PCM if the transfer case is in 4x4 low. If it were to tell the PCM it is in 4x4 low when it is not the trans will shift to a higher gear much too soon. It cannot make it go to neutral.
PCM failures do happen, but they are very, very rare.
The only input to the PCM from the transfer case is the switch that tells the PCM if the transfer case is in 4x4 low. If it were to tell the PCM it is in 4x4 low when it is not the trans will shift to a higher gear much too soon. It cannot make it go to neutral.
PCM failures do happen, but they are very, very rare.
Thanks Mr. Kovalsky.....you have been very helpfull!
Last edited by autotech2; Sep 10, 2011 at 09:25 AM. Reason: Additional info
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From: Spanaway
Just in case anyone is following this post........I brought it to the dealer thinking it was the computer and decided to let them diagnose the problem. They said it was in the trans so I installed a known good used trans and the same symptoms where there. I brought it back to the dealer and the said it was in the transfer case. I was skeptical but replaced the TC anyway and it solved the problem. Anybody out there have a clue as to HOW?
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