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My O/D light is blinking yellow

170 Views 6 Replies 3 Participants Last post by  amc49
I recently got a 2004 focus zts and I decided I needed to change my transmission fluid judging by the color. I also changed the filter since I wasn’t sure what condition it was in. I thought everything went pretty smoothly but after I test drove it, it was struggling at speeds above 40mph. It was changing gears too fast and for no reason. After a little bit the O/D light started blinking yellow so I pulled over and started checking things, the fluid level is good I checked it on level ground. I’m trying to figure out what could be wrong, it’s never had any problems like this before I changed the fluid. I’m wondering if it might be the speed sensor, I had to unclip it and reclip it in replacing the filter. If I didn’t do it properly could it cause this problem? Has anyone else had anything similar to this happen after a transmission filter change?
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Assuming you ARE checking fluid level with ENGINE RUNNING?

If fluid was black before changing you waited too long and new fluid can make trans worse.

Not a speed sensor, a temperature sensor attached to filter.
 

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Discussion Starter · #3 ·
Assuming you ARE checking fluid level with ENGINE RUNNING?

If fluid was black before changing you waited too long and new fluid can make trans worse.

Not a speed sensor, a temperature sensor attached to filter.
Yes I am checking it with engine running on level ground, the Transmission fluid was dark in color so I’m sure it wasn’t changed when it should’ve been. What are the steps I can take now? I ran a obd scan and got a few codes, one that stood out is P0734 which states “Gear 4 Incorrect Ratio”. Am I going to need a new transmission?
 

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Discussion Starter · #4 ·
Assuming you ARE checking fluid level with ENGINE RUNNING?

If fluid was black before changing you waited too long and new fluid can make trans worse.

Not a speed sensor, a temperature sensor attached to filter.
The scanner grabbed a few codes another is P0751 and it’s saying “Shift solenoid A Performance or stuck off”
 

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Solenoid A is for getting 4th gear (OD). maybe that as it applies to the other code too.

However the fluid change if the cause says more worn parts than anything, that trans is well known for wearing at the driver side end cover of trans to then mess the direct clutch up, which is needed in 3 and 4. The solenoid code may be because of that too, as the code can only report solenoid getting out of normal range, which it will do when the hydraulic circuit it controls goes awry from wear allowing fluid leaks. A line pressure check would likely show that wear.

Mileage on car? A big indicator of end cover wear. Another is reverse slowly bumping up when you first put trans in reverse with cold fluid. INstant firm bump what you are looking for, a second delay and lesser firmness says cover leaks.
 

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I recently got a 2004 focus zts and I decided I needed to change my transmission fluid judging by the color. I also changed the filter since I wasn’t sure what condition it was in. I thought everything went pretty smoothly but after I test drove it, it was struggling at speeds above 40mph. It was changing gears too fast and for no reason. After a little bit the O/D light started blinking yellow so I pulled over and started checking things, the fluid level is good I checked it on level ground. I’m trying to figure out what could be wrong, it’s never had any problems like this before I changed the fluid. I’m wondering if it might be the speed sensor, I had to unclip it and reclip it in replacing the filter. If I didn’t do it properly could it cause this problem? Has anyone else had anything similar to this happen after a transmission filter change?
The problem is that if the car is high mileage or old and the AUtomatic Tranny fluid has never been changed is better not to touch it. THe clutch friction material was suspended on the old oil, thus the smell and consistency. What you can do is try now to add anti slip additive to see if it helps if not you messed it up really good. If the oil is not changed every 30 miles since new then that is a not touch item .
 

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Either way the trans is likely dead worn out. The old fluid was thickened up and had wear particles in it that helped the clutches to grab. Fine, it was running but that far gone the trans will be slipping in another month anyway.

Why most shops will no longer change fluid that has not been done in forever, they do it and then the clean new fluid makes the trans slip and then the driver blames the shop when they did nothing wrong. Driver problem there, not taking proper care of the car.
 
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