E4OD lockup issues
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Senior User
Joined: Nov 2012
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From: Central Iowa
E4OD lockup issues
So on my new to me 1992 F350, I've been having an issue with lockup.
Transmission has clean fluid and at the correct level, and shifts up and down on time every time, through all gears.
However, there is no lockup in third or fourth, unless the throttle is at 80-100%. As soon as there is less throttle than 80% or so it unlocks immediately. There are no codes and no flashing O/D light. Like I said all shifts are on time as expected.
I replaced the speed sensor in the differential as it was bad. My RABS light is still on. Speedometer works fine with no cutouts or intermittent operation. Cruise also does not work (but that may or may not be related). There are no LED lights on the truck, and brake lights work as intended.
I've replaced the FIPL and set it to 1.2v at idle, engine off key on, and WOT is ~3.8v.
Still, the torque converter will only lock at WOT or nearly WOT. This is true for both O/D and 3rd (disabling O/D via switch).
The transmission operates flawlessly apart from this one issue.
Any ideas or things to check?
Thanks in advance!
Transmission has clean fluid and at the correct level, and shifts up and down on time every time, through all gears.
However, there is no lockup in third or fourth, unless the throttle is at 80-100%. As soon as there is less throttle than 80% or so it unlocks immediately. There are no codes and no flashing O/D light. Like I said all shifts are on time as expected.
I replaced the speed sensor in the differential as it was bad. My RABS light is still on. Speedometer works fine with no cutouts or intermittent operation. Cruise also does not work (but that may or may not be related). There are no LED lights on the truck, and brake lights work as intended.
I've replaced the FIPL and set it to 1.2v at idle, engine off key on, and WOT is ~3.8v.
Still, the torque converter will only lock at WOT or nearly WOT. This is true for both O/D and 3rd (disabling O/D via switch).
The transmission operates flawlessly apart from this one issue.
Any ideas or things to check?
Thanks in advance!
Thread Starter
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Senior User
Joined: Nov 2012
Posts: 192
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From: Central Iowa
Figured out the lockup issue.
I was aware of LEDs causing issues. I didn't think this truck had LED lights on the rear as they looked like incandescent housings and lenses (you know how you can usually see the LEDs clearly). Well I figured I should check and see if a filament collapsed in a bulb, opened up the light and it was a non-replaceable LED fixture. Go figure. Got a load equalizer (6ohm) and installed it in series on one side. Fixed my lockup issue AND turned off my RABS light.
The clue? With key on and ALL lights off, the rear lights had a very faint glow. Apparently the computer check has enough voltage to very slightly illuminate LEDs, which we already know don't load the circuit enough and causes the TCM and RABS system to see a fault.
Oh well. It works now.
One question though, the shifts and lockup seem just a hair early. Its in O/D by 35MPH and it'locks up almost immediately. Is this normal on these?
I was aware of LEDs causing issues. I didn't think this truck had LED lights on the rear as they looked like incandescent housings and lenses (you know how you can usually see the LEDs clearly). Well I figured I should check and see if a filament collapsed in a bulb, opened up the light and it was a non-replaceable LED fixture. Go figure. Got a load equalizer (6ohm) and installed it in series on one side. Fixed my lockup issue AND turned off my RABS light.
The clue? With key on and ALL lights off, the rear lights had a very faint glow. Apparently the computer check has enough voltage to very slightly illuminate LEDs, which we already know don't load the circuit enough and causes the TCM and RABS system to see a fault.
Oh well. It works now.
One question though, the shifts and lockup seem just a hair early. Its in O/D by 35MPH and it'locks up almost immediately. Is this normal on these?
Elder User
Joined: Sep 2018
Posts: 735
Likes: 8
From: NC
that does seem a little early, mine under normal accel will shift into OD at about 42 mph and will stay in OD down a bit lower than that if I am light on the throttle, if I give it anything more than the lightest push it will down shift into 3rd again then go back into OD 42 to 45 ish. If I am in stop and go traffic in town (max speed limit around here in town is 45) I shut off OD
Fleet Owner
Joined: Oct 2005
Posts: 20,789
Likes: 1,753
From: Kentucky
Do you have larger than stock tires? If so, did you change the calibration constant in the PSOM?
Logistics Pro
Joined: Aug 2014
Posts: 3,570
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Figured out the lockup issue.
The clue? With key on and ALL lights off, the rear lights had a very faint glow. Apparently the computer check has enough voltage to very slightly illuminate LEDs, which we already know don't load the circuit enough and causes the TCM and RABS system to see a fault.
Oh well. It works now.
The clue? With key on and ALL lights off, the rear lights had a very faint glow. Apparently the computer check has enough voltage to very slightly illuminate LEDs, which we already know don't load the circuit enough and causes the TCM and RABS system to see a fault.
Oh well. It works now.
Fleet Owner
Joined: Oct 2005
Posts: 20,789
Likes: 1,753
From: Kentucky
The OP's 1992 F350 does not have the high mount third brake lamp. It's only a cargo lamp.
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Senior User
Joined: Nov 2012
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From: Central Iowa
While lockup works I've got a weird issue with quick unlock and back locked randomly. It appears to be related to my MFS, as each time I turn on the turn signal either direction it messes with the torque converter lockup. Wonder if I need to put a load equalizer on the right side too in addition to replacing the MFS.
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Elder User
Joined: Sep 2018
Posts: 735
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From: NC
No 3rd brake light on this truck.
While lockup works I've got a weird issue with quick unlock and back locked randomly. It appears to be related to my MFS, as each time I turn on the turn signal either direction it messes with the torque converter lockup. Wonder if I need to put a load equalizer on the right side too in addition to replacing the MFS.
While lockup works I've got a weird issue with quick unlock and back locked randomly. It appears to be related to my MFS, as each time I turn on the turn signal either direction it messes with the torque converter lockup. Wonder if I need to put a load equalizer on the right side too in addition to replacing the MFS.
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