Good afternoon, SF. Who's got knowledge on automatic transmissions?

Ex-GF and I have remained good friends, and she emailed me last night. The subject line read, "Help," and frankly that scared the crap out of me. I was already looking for my shoes before I got started reading the content of the message. But I digress....

She's got a 2001 Nissan Pathfinder LE. VQ-series V6, automatic. She loves her PF (230K miles) about as much as I love mine (268K miles).

The symptom (and the real reason for her message) is that when she puts it in reverse, it doesn't move at all. She's about a two-hour drive from me, so I can't really get my hands on it, but she asked me for help and I offered to learn whatever I could for her. She said it drives fine going forward, but won't move backward.

I asked her this morning if it accelerates as it should, and whether it will move forward when the shifter is in the "1" or "2" positions. I asked if the multifunction indicator light is on (and if she's had the codes read), and if the overdrive light is blinking at all.


I know diddly about automatic transmissions, really, but I do know there's a solenoid in the system somewhere. Working in electronics daily, I've asked her to check all the fuses and any relevant relays. Beyond that, I'm not sure what tests an average owner (Well, she's above average! Plus she's smart, and she's mechanically inclined.) can do on her own before having to spend a pile of money on testing.

As stated before, I know she loves her PF and (despite influences from others) is in no way ready to trade it. I'm hoping there's a simple and relatively inexpensive fix. I recognize it's hard to diagnose from across the Internet, but I do appreciate your help. Thanks, all.

https://www.2carpros.com/quest...on-will-into-reverse


Maybe that?

She needs to find an honest transmission repair place with the tools to accurately diagnose the problem. It may or may not be fairly minor and as we all know, some shops will try to sell the whole transmission rebuild which may not be needed. We took our 2005 Buick to a nice honest local repair shop and spent $500 for diagnosis of a very rough shift, two solenoids, and new fluid and filter. It sure beat $3000 for a new transmission. Hunt for recommendations on a shop in her area. Make sure they are Nissan familiar.

It might help if you ask her this: When you put it in gear, you know how it feels? You can definitely feel a movement when you move from Park to Reverse, from Reverse to Neutral, from Neutral to Drive, Neutral to Reverse. Sort of a "torque down" movement and feeling.

If she can articulate this it might be helpful to diagnose the problem. This will indicate if the transmission is actually going into reverse, or not, and will steer you in the correct diagnostic direction.

Best wishes to y'all.

See if she can check the fluids. Nissan has had a problem with ATF mixing with coolant in the radiator before. You would see a milkshake in the rad or the trans fluid. If so, its a definite goner, not worth the cost of repair.

If that checks out, it is probably the band in the transmission. There is a band that engages when reversing. That can let go and you lose reverse gear. Usually cheaper to replace the trans than fix it.

I don't think she'll get out of it for less than $1600 at best so she'll have to decide if it's worth fixing a 17yr old truck.

Oz, thank you for the link. I read that same page last night.

Gene H: I'll be looking for a shop in her area... I'm hoping it's a fluid/filter thing (though she did tell me that at least the fluid level is good).

OKCGene: I know the sensation you're describing. She's mechanically-inclined, and if I can get her by phone soon I can ask her about that.

Scurvy: I know the "pink milkshake" issue you mention. I believe (not certain, admittedly) that was an issue with the 4.0-liter engines in the R51 series (our '01 and '02 are of the R50 series). Is it worth fixing? She and I would probably say, "absolutely."

My (limited) experience is leaning toward the pump. Many transmissions modulate the hydraulic pressure in the pump. Park & Neutral is 0 PSI. Forward gears are 65 - 80 PSI. Reverse is 120 - 140 PSI. The higher pressure is needed to compress the reverse clutch pack to engage the planetary gearset. If it drives fine in all forward gears and has no load (no decrease in RPM) in reverse, perhaps it only puts out 100 PSI or so. It is possible for the gearotor style pump to lose pressure over time.

I've rebuilt one truck transmission that was axeploded inside and have repaired several Nissans that wouldn't shift.
The Nissans needed the soleniods to come out and their strainer filters cleaned out.
After that it's leaking pressure internally somewhere.
It has the Jatco RE4R01A.
Same one in my wife's 300ZX

You can unplug all the sensors on that transmission and it will still back up.
I hate to tell you this but it's toast. Age coupled with miles says it's a gonner.No way will that be a cheap fix. Not knowing your area but don't be surprised to hear $2500+

quote:

Originally posted by ScreamingCockatoo:
It has the Jatco RE4R01A.

That's good info, SC. Thank you for that! A quickie Google surf led me to a PDF that suggests it may be as simple as the control linkage being out of whack. More research to do! Could this also be as easy (relatively) as removing and cleaning those filters?

21bubba, does your first sentence tell me that there's something that could be unplugged temporarily to get her going for a couple of days? Or am I misunderstanding?

quote:

Originally posted by vthoky:

quote:

Originally posted by ScreamingCockatoo:
It has the Jatco RE4R01A.

That's good info, SC. Thank you for that! A quickie Google surf led me to a PDF that suggests it may be as simple as the control linkage being out of whack. More research to do! Could this also be as easy (relatively) as removing and cleaning those filters?

21bubba, does your first sentence tell me that there's something that could be unplugged temporarily to get her going for a couple of days? Or am I misunderstanding?

I think what bubba is trying to say is that if you had a good working transmission, you could unplug everything and it will reverse.

quote:

Originally posted by Shifferbrains:

quote:

Originally posted by vthoky:

quote:

Originally posted by ScreamingCockatoo:
It has the Jatco RE4R01A.

That's good info, SC. Thank you for that! A quickie Google surf led me to a PDF that suggests it may be as simple as the control linkage being out of whack. More research to do! Could this also be as easy (relatively) as removing and cleaning those filters?

21bubba, does your first sentence tell me that there's something that could be unplugged temporarily to get her going for a couple of days? Or am I misunderstanding?

I think what bubba is trying to say is that if you had a good working transmission, you could unplug everything and it will reverse.

That's what I meant.

I have a very good friend that has built transmissions for about the last 20 years. He said there is no way to tell unless you dig into it, and at that point, with that much mileage on the trans you just rebuild it if she wants to keep the car. If she wants to sell it and get out cheap than that is another topic. But usually, when a trans has one problem at that kind of mileage everything else is close to worn out too and the clearances are on the wide side of spec best case scenario.

Only comment I can make is some long past experience... why rebuild it? Just replace it with an already rebuilt or new one... much less time on the rack.

The reverse sprag is probably toast.
Unfortunately the Jatco is not an easy rebuild as you have to get tools or make tools to snatch out a few parts.
But it's not impossible.
I'm crafty enough to rebuild it myself.
Maybe $400 in parts.

quote:

Originally posted by ScreamingCockatoo:
I'm crafty enough to rebuild it myself.
Maybe $400 in parts.

[Wishing ExGF and the cockatoo tree were each closer to me....]

What's a sprag?

I've found there's a good shop near her home, so that's a good thing. I'm hoping (as is she) that it can be rebuilt or replaced without major hassle.

I've had a rebuilt engine put in an old Nissan truck long ago, but never dealt with a rebuilt transmission. Based on last night's surfing, it looks like parts kits are not terribly expensive -- I'm guessing the labor is the booger. Anyone got ballpark costs on rebuilding one or installing a rebuilt one?


I know if I were in her shoes, I'd repair the trusty Nissan before replacing it. I think she will, too.

At this point I think you can estimate a range of $300 to $3000 for the job and nothing closer until someone competent diagnoses it.

quote:

What's a sprag?

Sprag clutch

If this, or something like it, is the problem, and I don't doubt it is, the transmission has to be taken out and broken down. It is not an in-the-vehicle repair. No shop worth their salt is going to put that transmission back together with the rest of the old, 200,000 mile parts still in it.

Unless this 230K miles and 17 year old truck is absolutely perfect except for the transmission. It's not worth what it will wind up costing to fix.

Thanks, egregore!

I know it's 17 years old and got a pile of miles on it... but I know what its "true worth" is to her. (Essentially, the same as mine.).

Heck, $3K to fix it is still far better than $20-30k to replace it. I've had mine since its odometer showed a mere 251 miles, so I know its care and condition. Hers, we bought with just under 100K on the clock -- based largely on how well mine had held up at that point -- but I believe she's taken good care of hers as well.