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David Gieswein
David Gieswein,
Category: Transmissions
Satisfied Customers: 103
Experience:  Automotive technician at Doug Gray Dodge/Chrysler/Jeep
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I have a 2006 Nissan Pathfinder, I just recently bought it

Customer Question

I have a 2006 Nissan Pathfinder, I just recently bought it and shortly after it, it ran P 1772 and I lost reverse and second gear used my code reader to erase the code and it went back to normal and then a few days later I while was driving it kept falling out of gear it would just rev up when pressing the excelorater I just used the code reader to erase the new code PO507 every time it happened and it went back to normal, I ended up doing a tranny flush and replacing the screen, after all that it was driving fine and now it's having trouble going into overdrive and on some days I don't have overdrive at all when I turn overdrive off I don't have any problems at all but no light or code running at all it's not contaminated as far as I know as it's clean and it is bypassed at this point I have done 3 different relearn procedures since doing the tranny flush. I'm at a loss on what to do and the next step to take
Submitted: 1 month ago.
Category: Transmissions
Expert:  Jay replied 1 month ago.

Hello my name is ***** ***** thank you for your question.

What codes are you exactly getting now?

Customer: replied 1 month ago.
It's throwing no codes
Expert:  Jay replied 1 month ago.

If it is throwing no codes, then you have a mechanical issue causing your problem. Not electrical. So you have a internal issue with in the transmission which will eventually require transmission repair or replacement.

Expert:  Jay replied 1 month ago.

I worry more with no codes. At least if there was codes, it could possibly be solenoid or a Valve body. But when there is no codes, that means it's a mechanical issue I am afraid.

Customer: replied 1 month ago.
I realize that but I'm trying to get more insite on things to try and do. E.g. Procedures, things to try...
Expert:  Jay replied 1 month ago.

Well the steps would be to do line pressure tests. Stall tests, then drop the valve body and do air checks for each gear to see which gear is causing the loss of pressure for overdrive

Expert:  Jay replied 1 month ago.

This way, when you take the transmission out, you know what area to inspect for your exact issue.

Customer: replied 1 month ago.
You say it's machanical but could this have anything to do with throttle position sensor or vacuum leak or excelorator petal
Expert:  Jay replied 1 month ago.

No.. Not at all.

Customer: replied 1 month ago.
accelerator pedal position sensor
Expert:  Jay replied 1 month ago.

I know what you meant. No a APP sensor will not keep overdrive from operating. If you had a issue with the APP sensor, you would certainly have codes.

Customer: replied 1 month ago.
but im asking that cause when I had the 1772 code the low coast isn't coming on anymore since I have done the tranny flush
Expert:  Jay replied 1 month ago.

That is for the low coast solenoid valve. That is electrically controlled by the TCM. If your not getting that code any more, the flush may have cleared out any debris that may have been in the solenoid.

How many miles on the truck?

Customer: replied 1 month ago.
224000
Expert:  Jay replied 1 month ago.

You flushed the transmission with that many miles?

Customer: replied 1 month ago.
changed the strainer screen
Customer: replied 1 month ago.
No 224000km not miles
Expert:  Jay replied 1 month ago.

So that is around 139k miles. You should never flush a transmission with over 100k miles. That could do internal damage if the transmission has not been serviced properly

Customer: replied 1 month ago.
Well I had no choice as the tranny fluid looked like a mud puddle
Expert:  David Gieswein replied 1 month ago.

Hello my name is ***** ***** I can help you. I have reviewed your previous talks with Jay. From the last statement about the tranny fluid looking like a mud puddle, there is a very high chance the radiator went out before you bought it and contaminated the trans fluid. This is a common issue with the mileage you have. Once that happens you can kiss the valve body goodbye and most of the time the trans as well. My recommendation would be to find another trans with lower mileage. We use LKQ.com at our dealership and have had good luck. If you have any questions feel free to ask!

Customer: replied 1 month ago.
That's what I was thinking that they coolant and trans fluid mixed and they fixed the rad but never changed the trans fluid i did the bypass anyways just so I didn't run into that issue if that was the case it's funny way better now since doing the flush the only issue that has surfaced now is that it doesn't want to engage in over drive it revs up a bit before engaging and in order for that to happen you have to press then gas down a bit if that makes sense
Expert:  David Gieswein replied 1 month ago.

The problem is that the TCM is a part of the valve body. Once coolant is introduced it somehow damages either the valve body or the TCM. I have seen the TCM short out and take out the entire BUS network until you unplug it. You can replace the valve body, however, you need to check the price of a valve body vs. a entire trans assy. If you do just replace the valve body, keep in mind you will have to have it programmed at the dealer. The cost should be 1.5hrs to replace valve body + .5hr to program TCM. Plus addition of more fluid to refill the trans. If the valve body still doesn't fix the issue, then the trans will have to be disassembled and a possible replacement of the overdrive clutches will be necessary. It is a tuff decision I know. However, if you just replace the trans, you stand a better chance of illuminating comebacks. Replacing just the valve body is rolling the dice, most of the time you will lose. I have tried replacing the valve body only to have to put a trans into it later cause the issue didn't get fixed.

Customer: replied 1 month ago.
Could it be electronic?
If I drive it with the over drive off will it hurt the tranny?
Expert:  David Gieswein replied 1 month ago.

If you drive it with the overdrive off you will not only damage the trans further but make your engine work at higher rpms. If you are trying a temporary fix you can go to autozone and buy some Lucus trans additive. Maybe it will help fix the issue for now. You may have a valve sticking somewhere not applying enough pressure to the friction clutches. It is worth a shot!

Expert:  David Gieswein replied 1 month ago.

I am logging off for now but will be back on tomorrow.