2001 Pathfinder transmission woes

[pathfinderwoes]

My 2001 Pathfinder 4WD with 168K miles has recently started experiencing transmission problems. At highway speeds the transmission felt "jittery" At the same time I received code P0744 (Torque Converter Clutch Ciruit Intermitent) . Went to Nissan dealership - they replaced the solenoid and changed the trans fluid. Within a couple days, same condition occurred. I was hoping it would only affect overdrive - but when i switched out of OD, within a 10 minutes at highway speed the ride would again become rough (in 3rd gear). Any thoughts of things to try short of a trans overhaul/replacement?

[MinisterofDOOM]

Sounds like it might just be a problem with torque converter lockup actuation. Might be a bad solenoid, or a problem with signal to it.

[alms24sebring]

Torque converters themselves don't go bad do they? It's pure mechanical. Although I don't know exactly where the tq converter clutch solenoid is.

[Towncivilian]

A transmission "flush" is usually nothing more than a fluid exchange using the transmission's own pump, and is something you can do at home to avoid the labor charge. You don't want a shop potentially adding solvents, cleaners etc during the exchange process, anyway.

To do a cooler line exchange:

• 1. Disconnect the transmission cooler return line (passenger side) and secure into a container that can hold 3 gallons or so
• 2. Have a helper turn the engine on while you watch the container; after roughly 2 quarts have been drained, shout for your helper to turn the engine off. At this time, add 2 quarts of ATF through the dipstick, and repeat this step until you have exchanged all of the fluid (9 quarts - may as well exchange 10 quarts).

[alms24sebring]

If you read it he said he got it flushed.

168k sounds like about the life of a trans

[Towncivilian]

Oh, I think the OP edited the post and I had replied to his previous revision.

Did you get a complete fluid exchange or just a drain & fill (or pan drop amount)?

[Chris.m]

Torque converters themselves don't go bad do they? It's pure mechanical. Although I don't know exactly where the tq converter clutch solenoid is.

My torque converter "shattered" after I went over a bump. It then sent pieces of metal into half the gears.

[pathfinderwoes]

Thanks for the posts back - to better clarify what was done (I hope it clarifies it)

I was told the dealership performed a complete fluid exchange along with new filter. I also had the solenoid replaced (tourque converter lockout solenoid) that the error code referred to.

I guess it could have been a bad replacement solenoid but i imagine that is wishful thinking.

[pathfinderwoes]

One shop I went to looked at the code and said all they would do was to to simply replace the transmission...they said it wasn't worth their time troubleshooting the problem.

[Towncivilian]

Did you get a 1yr/12k mi warranty on the work that Nissan performed? Perhaps you can have them replace the solenoid again, and if that doesn't fix things then maybe it is time to look for a new transmission or a quality rebuild by a reputable trans shop.

[MinisterofDOOM]

A solenoid or circuit issue isn't going to be corrected by a fluid flush. It's an electronic problem. Since you've already replaced the solenoid with no improvement, I'd start looking at the electronics that control the solenoid.

Stay far away from the shop that told you they'd rather replace than diagnose. The error code and your syptoms support each-other, and both point to a relatively simple electronic problem. Replacing the entire transmssion without first doing some basic electronic diagnostics is ludicrous overkill. Blindly throwing parts at a problem is the first sign of a bad mechanic.

[yeldogt]

The lockup mechanism do go out just like anything else.

Changing the fluid is often recommended in the hope that maybe introducing fresh solvents in the new fluid will free up anything that may be stuck in the solenoid/ valve ........ this is normally wishful thinking.


I would return to Nissan and at the very least get a definitive answer as to the transmissions likely problem. They should at least know the different operations for a particular code.

[ARKQX33V6]

From experience I have noted solenoid problems with the transmission from a fouled solenoid from debris in the fluid.

That said, there are times that a fluid exchange will actually clean out the mechanical parts of the operational solenoid. But solenoids are electro-mechanical devices controlling hydraulic actuators that rely on hydraulic pressures. Many things can take place.

All told these devices need an input signal, electrical or electronic, that signal must be strong enough and long enough.

The electrical actuator must respond and be strong enough to operate the mechanical parts of the solenoid. Too slow mechanically will increase amperage electrically and reduce magnetic pull and reduce voltage, this can take out primary voltage source or pop a fuse.

The mechanical solenoid must be strong enough to activate and quick enough as it changes direction in the hydraulic flow. Too slow an action slows the reaction hydraulically and the electrical signal quality.

Hydraulic flow must be quick, pressure rated and volume flow high enough to do the work that the pressure of the fluid is supposed to do.

So you can see that a simple solenoid can get very involved with the thing that it operates.

If when going from 1st to 2nd the set of solenoids are hung up even for a short time the output can be felt by the operator of the car and with a sloppy shift; the first thing the operator does is give it more gas. This increases the pump RPM and increases the flow possibly to the max that the relief valve is set and that jittery feeling.

As was said earlier, sometimes a fluid exchange will fix this because the crap in the fluid is removed, sometimes!

Some shops do not want to play with transmissions, some do, those that do should be trained and full of know how. Hydraulic mechanisms are complex, control with electronic, computer, and various voltages add to the complexity but to a knowledgeable person it takes time, patience and a bit of testing and it seems that companies do not want to train these people, because they might leave for an additional $1 an hour.

This is the plight of today's modern high tech world. A lot of companies think it is better to replace than to repair because their cost go lower when less training is needed. Rebuilding a complex thing compared to replacing that complex thing....