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2003 Mercury Sable DOHC
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Discussion Starter #1 (Edited)
2003 sable DOHC, 97k, I bought it last year at 84k.
Asking for advice on rarely occurring transmission flashing light. Finally I was able to read the code - P0741. It actually said "TC Clutch slip above expected" . (my regular obd didn't read a code. I had with me an Autel ML629, and that found the code with the description above).
I had another discussion on this in this forum - it happens rarely, only on long trips, after a few hrs on the highway, and if I stop and turn the engine off and on, it doesn't happen again for the rest of the trip, even if I drive another 600 miles.
It never happens on short trips. Also: absolutely no hard shifting or anything like that. Just the light and the extra RPM when the light is on.
This time I came out of a gas station after 4 hrs of driving, merged on the highway by flooring it (situation required it), so I pushed it into very high RPMs, and then set the cruise at 74mph. Looking at the tachometer, the rpm was just a tad under 3000, which is not normal for my car at 75mph. I usually hit 3000rpm at or above 80mph. I thought it was odd, and right at that moment the flashing tranny light came on. I pulled over, read the code above, turned the engine on and off, and it never happened for the rest of the trip, nor since.
Important detail: it did the same last summer but I couldn't find a code with my regular OBD and torque pro app. It was the same on every single trip above 4hrs. I changed the fluid and filter, added an extra magnefine inline filter, and went back on a 10 hr trip. Light didn't come on at all during the return trip, so I thought it was fixed. Now, 6 months later, here it is. So it temporarily got fixed after I dropped the pan and changed the fluid and filter.
I had already checked the electric harness and all wires are ok, I have a new 90degrees angle tranny vent, and a tranny extra cooler. Fluid level ok and in good condition.
So, what next? Change the fluid again completely? A flush? Torque converter itself? TCC solenoid? Can I just leave it like this and turn the engine off/on and move on the 2 times a year I travel out of state (it )?
Any directions or personal experiences would be very very appreciated. Thank you
 

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Personally I'd just leave it alone until the code stays on permanently. It's a lot of work to chase this issue. Since you've already changed the fluid and filter, there's only two possibilities. One, there's an issue with the TCC solenoid or its regulator valve on occasion and it's not properly locking up the torque converter clutch. Possibility two is that the converter clutch itself is wearing out and soon you'll lose lockup completely. There are also other rare possibilites involving the valve body or the pump shaft/stator shaft, etc. But most of these still revolve around mechanical wear that you can't do anything about without a rebuild.

If you want to try removing the main cover plate over the valve body/solenoid pack, and preemptively replacing the TCC solenoid, this will show you which one you need to replace. But other than swapping that, I would stick to my original advice and just leave it alone with as intermittent as it is. https://atracom.blob.core.windows.net/bulletins/2005/july/atb935.pdf

You can remove the main cover plate with the transmission in the vehicle, although you will have to remove the transmission mount and lift the unit with a jack slightly to gain the necessary access.
 

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2003 Mercury Sable DOHC
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133 Posts
Discussion Starter #3
Personally I'd just leave it alone until the code stays on permanently. It's a lot of work to chase this issue. Since you've already changed the fluid and filter, there's only two possibilities. One, there's an issue with the TCC solenoid or its regulator valve on occasion and it's not properly locking up the torque converter clutch. Possibility two is that the converter clutch itself is wearing out and soon you'll lose lockup completely. There are also other rare possibilites involving the valve body or the pump shaft/stator shaft, etc. But most of these still revolve around mechanical wear that you can't do anything about without a rebuild.

If you want to try removing the main cover plate over the valve body/solenoid pack, and preemptively replacing the TCC solenoid, this will show you which one you need to replace. But other than swapping that, I would stick to my original advice and just leave it alone with as intermittent as it is. https://atracom.blob.core.windows.net/bulletins/2005/july/atb935.pdf

You can remove the main cover plate with the transmission in the vehicle, although you will have to remove the transmission mount and lift the unit with a jack slightly to gain the necessary access.
Thank you a bunch! That is in line with what I was thinking, and a confirmation from an experienced person is what I needed. Hopefully it will be this intermittent for a long time.
Many thanks for the detailed response and info!
 

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2003 Mercury Sable DOHC
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133 Posts
Discussion Starter #4
Personally I'd just leave it alone until the code stays on permanently. It's a lot of work to chase this issue. Since you've already changed the fluid and filter, there's only two possibilities. One, there's an issue with the TCC solenoid or its regulator valve on occasion and it's not properly locking up the torque converter clutch. Possibility two is that the converter clutch itself is wearing out and soon you'll lose lockup completely. There are also other rare possibilites involving the valve body or the pump shaft/stator shaft, etc. But most of these still revolve around mechanical wear that you can't do anything about without a rebuild.

If you want to try removing the main cover plate over the valve body/solenoid pack, and preemptively replacing the TCC solenoid, this will show you which one you need to replace. But other than swapping that, I would stick to my original advice and just leave it alone with as intermittent as it is. https://atracom.blob.core.windows.net/bulletins/2005/july/atb935.pdf

You can remove the main cover plate with the transmission in the vehicle, although you will have to remove the transmission mount and lift the unit with a jack slightly to gain the necessary access.
Thank you a bunch! That is in line with what I was thinking, and a confirmation from an experienced person is what I needed. Hopefully it will be this intermittent for a long time.
Many thanks for the detailed response and info!
 

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My son's 2001 Taurus had somewhat similar issue, but worse to where the tranny light stayed on and tranny locked up to move at a slow crawl with NO power. Issue was wiring harness adjacent to catalytic converter which got burnt and shorted when he hit a bump or shifted from neutral into drive which caused a 'bump' which moved the wires around to short (all insulation burned off). This can only be seen from below, and was ez to fix after seeing what was going on. Hope this helps :)
 

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2003 Mercury Sable DOHC
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133 Posts
Discussion Starter #6
My son's 2001 Taurus had somewhat similar issue, but worse to where the tranny light stayed on and tranny locked up to move at a slow crawl with NO power. Issue was wiring harness adjacent to catalytic converter which got burnt and shorted when he hit a bump or shifted from neutral into drive which caused a 'bump' which moved the wires around to short (all insulation burned off). This can only be seen from below, and was ez to fix after seeing what was going on. Hope this helps :)
Thanks for the tip! I will get under there and take a look, just to make sure.
 

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2003 Mercury Sable DOHC
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133 Posts
Discussion Starter #7
Short update: I thought back trying to identify when the light would come on, and there is a pattern. It happened only after: 1. some hrs of driving and 2. a high rpm shift from 3rd to 4th (ex. getting on the highway, or being on cruise going up a steep hill, and the car shifts into 3rd at 4500 rpm to maintain the speed).
As a result, on the return trip yesterday (550 miles), I was cautious when merging on the highway, and no flooring it. What do ya know, the light never came back, and the TC locked correctly every time. Hopefully it will last for a long(er) time without me needing to change anything. I will update if anything else happens.
 
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