Help! E40D limp mode
Frmr Ford Trans Engr
Joined: Aug 1999
Posts: 24,732
Likes: 2,661
From: SE Florida
There is no ground wire on that connector. There are switched grounds that turn the solenoids on and off, and there is signal return, which should NEVER be used for grounding as that could damage the PCM.
Tuned
Joined: Jan 2015
Posts: 476
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Verify your grounds also. There's one from the firewall above the A/C to the bracket supporting the upper intake, there's the negative side of the battery, there's one from the battery to the frame on the passenger side of the engine which also connects to the engine block behind the smog pump, and then there's the one at the battery that connects to the inner fender wall.
Fleet Owner
Joined: Aug 2005
Posts: 23,667
Likes: 301
From: Easton,Ks
The Sig-Return is grounded through the computer to the passenger fender also called the body ground, G101. This is the only electrical ground for the PCM. There is also a case ground pin #20 and is grounded on the drivers fender at G104.
G101:
G104:
/
Fleet Owner
Joined: Aug 2005
Posts: 23,667
Likes: 301
From: Easton,Ks
The frame only needs to be electrically grounded if you pull something like a trailer. If you do not pull anything the frame does not have to be electrically grounded.
That is what the center lug on the battery NEG cable going to the engine block is for.
I did not engineer the Ford electrical system so that is as best as I can do in answering your question.
Fleet Owner
Joined: Aug 2005
Posts: 23,667
Likes: 301
From: Easton,Ks
The MLPS (AKA TR sensor) has nothing to do with the solenoids.
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Frmr Ford Trans Engr
Joined: Aug 1999
Posts: 24,732
Likes: 2,661
From: SE Florida
The only way the solenoids could be the problem is if they all decided to fail at the same time. You know, a union of solenoids. They normally don't discuss with each other when they plan to fail. They are really bad about planning for several to all die at once.
Wiring harnesses, however, can have one wire fail and set a whole bunch of 600 series codes. Especially if the wire to pin #7 has a problem, and there is no power to the solenoids. These symptoms could also happen if each of the solenoid ground side wires (the ones in the diagram labeled with the solenoid they are connected to) fail at the same time. Damage to the harness CAN cause this.
As was stated above the MLPS has nothing at all to do with the solenoids. Stay out of that rabbit hole.
Thread Starter
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New User
Joined: Nov 2016
Posts: 23
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yes I know, but the mlps can cause the transmission to go into limp mode which is the problem I'm having. I know its solenoid related because of the codes but I'm exploring all thoughts lol.
Fleet Owner
Joined: Aug 2005
Posts: 23,667
Likes: 301
From: Easton,Ks
You more thank likely have a bad plug on the passenger side of the transmission or a rodent has ate some of the wiring going to the transmission or someone pinched or other wise messed up the harness to the transmission.
The KOEO part of the codes is an on the spot electrical test of wiring and the voltages in the engine and transmission harnesses. KOEO electrical test codes are not saved in the PCM, just displayed.
The KOEO part of the codes is an on the spot electrical test of wiring and the voltages in the engine and transmission harnesses. KOEO electrical test codes are not saved in the PCM, just displayed.
Frmr Ford Trans Engr
Joined: Aug 1999
Posts: 24,732
Likes: 2,661
From: SE Florida
How would the MLPS set codes for the solenoids? You're chasing ideas that CANNOT cause the symptoms you have.
Fleet Owner
Joined: Oct 2005
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From: Kentucky
An open circuit that is in close proximity to other energized circuits will measure a voltage when using a DVOM. Get an old iron vane VOM or a simple test light.
Fleet Owner
Joined: Aug 2005
Posts: 23,667
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From: Easton,Ks
By the way here is what the book says for those codes.
TC1 ENTER OUTPUT STATE DIAGNOSTIC TEST MODE (DTM)
DTCs 621, 622, 626, 629, 641 and 652 indicate solenoid did not change state when requested by the Powertrain Control Module (PCM).
Possible causes:
-- Damaged solenoid/assembly.
-- Open or shorted harness (internal/external).
-- Damaged PCM.
NOTE:
Use a VOM or DVOM.
VOM/DVOM on 20 volt scale.
Connect negative test lead to STO circuit at Data Link Connector (DLC) and meter positive test lead to B+.
Jumper STI circuit to SIG RTN at the DLC.
Perform Key On Engine Off Self-Test until Continuous Memory DTC have been displayed.
VOM/DVOM will indicate less than 1.0 volt when test is complete.
Depress and release throttle.
Does voltage increase?
Yes
REMAIN in Output State DTM. GO to «TC2».
No
DEPRESS throttle to WOT and RELEASE. If STO voltage does not go high, PERFORM Pinpoint Test Step «QC1». LEAVE equipment hooked up.
TC1 ENTER OUTPUT STATE DIAGNOSTIC TEST MODE (DTM)
DTCs 621, 622, 626, 629, 641 and 652 indicate solenoid did not change state when requested by the Powertrain Control Module (PCM).
Possible causes:
-- Damaged solenoid/assembly.
-- Open or shorted harness (internal/external).
-- Damaged PCM.
NOTE:
Use a VOM or DVOM.
VOM/DVOM on 20 volt scale.
Connect negative test lead to STO circuit at Data Link Connector (DLC) and meter positive test lead to B+.
Jumper STI circuit to SIG RTN at the DLC.
Perform Key On Engine Off Self-Test until Continuous Memory DTC have been displayed.
VOM/DVOM will indicate less than 1.0 volt when test is complete.
Depress and release throttle.
Does voltage increase?
Yes
REMAIN in Output State DTM. GO to «TC2».
No
DEPRESS throttle to WOT and RELEASE. If STO voltage does not go high, PERFORM Pinpoint Test Step «QC1». LEAVE equipment hooked up.