2006 M35X P1774 Transmission Code

[aidan2474]

So I did a search and I only found two threads specifically dealing with this issue. One did not have a resolution and the other thread had a fix of topping off the trans fluid.

What had happened was,....
Driving to work this morning on the highway feeling all good about my car with a 168k miles, as I just replaced the driver side wheel hub & bearing assembly all by myself, so it was a smooth ride doing about 70-75 with the intelligent cruise control working working again from the hub replacement. Then outta nowhere the trans slammed hard into neutral (WHAM!, car shakes), rpms shoot up and then the check engine light goes on. Rpms come back down and I am decelerating down the road in neutral even though I am in drive.
I hit the gas pedal and nothing, just the rpms went up , no engagement. I pull over on the shoulder, come to a stop, put the shifter in park and think for a minute on what to do next. I didn't want to turn the car off initially, so I put it back in drive, felt the trans engage and started to pull forward, unfortunately only first gear was available, it would not upshift. I then pulled back over and restarted the car. This time when I put it in drive and pulled away it drove like nothing was wrong, even though the check engine light remains on.
At lunch just now I went to Autozone and they pulled the P1774 code with no recommendations for fixes.

Hoping someone/anyone has some knowledge or interaction with this issue and some recommendations on how to fix.
Found these two articles, but not much use to me as a shady tree mechanic.
http://www.atraonline.com/gears/2007/20 ... _01_12.pdf
http://www.infinitig37.com/TSB/1ST25.pdf

[Ilya]

Something like this you may need to get a diagnostic from the dealer...could be anything.

https://www.autocodes.com/p1774_nissan.html

TCM? PNP? Vehicle Speed Sensor?

[Costee]

Actually, this is just another variation of a well-known (inevitable?) problem. It's the Achilles heel of our transmission (RE5R05A) one way or the other as the mileage increases. Specifically, it's a circuit issue in the TCM which is embedded in the valve body. You have three options: 1. Repair the TCM, 2. Replace the TCM, 3. Replace the valve body. There is a TSb on this issue (ITB10-006a) and typically the recommendation is to replace the valve body. There's a fourth but less likely option: the low coast brake solenoid valve which is the reference of P1774. It could be bad, but the case usually is that the circuit feeding it is bad. The FSM says the code "is not only caused by electrical malfunction (circuits open or shorted) but also by mechanical malfunction such as control valve sticking, improper solenoid valve operation." I wager it's an electrical malfunction. For an idea of what this is all about see this
https://www.youtube.com/watch?v=GAveITCubOQ

[aidan2474]

Wow , Great posted info and what an amazing, informative video. Thank you for that Costee!

It seems pretty simple, enough so that it looks like I could attempt it. I just got back from talking to a couple shops, one transmission shop and another mechanic , the trans guy said that its more than likely water in the transmission and its probably corroded. They would install a new valve body and re-route the cooling so no radiator fluid would contaminate the trans. They will not fix or repair any issues with the current parts, they will only install new valve bodies. They wouldn't even install a new TCM, quoted me around $3500 and then said that it would probably need to be programmed and they might have to get the nissan dealer to program it. The other shop said basically the same thing, they will only install new parts that come with a warranty as they do not want to get involved with customers who ask them to fix something that they cannot warranty. (as a side, I just had this same situation happen last week for my wife's car, which needs a new A/C condenser as the clutch went, quoted me $1400 total, also needed a new tensioner and ac belt, again would only get all new parts and associated parts, A/C drier, ect... as they need those accessory parts to be able to warranty the work.)

Luckily my wife works with a guy who is part owner of a shop and he said he would try to fix the issue with the TCM.

[tjdionson]

I'm currently in the process of "hoping" to fix my P1772 code on my 2007 m35. I have the valve body off and out and will try to replace the low coast solenoid. I really hope its not the TCM.

[tjdionson]

I have a question. Apparently there are 3 different types of low coast solenoid that come in our cars: "nachi", "mitsubishi", or "bosch". From the looks of it, it looks like my car comes with the nachi brand, but I'm having a really hard time looking it. I only see the bosch or mitsubishi brand. Does anybody know what the ohm ratings are on each? I was hoping the bosch and nachi were interchangeable. I tried to look at the part numbers on the solenoids but did not yield any results when i do a search.

[tjdionson]

Nvm, i think i found my answer. Read the comments on the youtube video.. lol "Sonnax says 'the Bosch, Nachi and Mitsubishi low coast solenoids can be freely interchanged. All three are 20-40 ohms. The odd 15-20 ohm solenoid was only used on Infinity up to August 2005'.
Will order tonight from ebay.

[Costee]

I'm currently in the process of "hoping" to fix my P1772 code on my 2007 m35. I have the valve body off and out and will try to replace the low coast solenoid. I really hope its not the TCM.

Since you have the valve body out why not verify that the circuit in the TCM has not been breached before deciding on getting a new solenoid.

[tjdionson]

I'm currently in the process of "hoping" to fix my P1772 code on my 2007 m35. I have the valve body off and out and will try to replace the low coast solenoid. I really hope its not the TCM.

Since you have the valve body out why not verify that the circuit in the TCM has not been breached before deciding on getting a new solenoid.

I would but I don't know how to :/.. would I be able to take it a mechanic to get diagnosed?

[Costee]

Watch the video
https://www.youtube.com/watch?v=GAveITCubOQ

[tjdionson]

Replaced the solenoids and fixed the problem!!! Smooth shifting now

[tjdionson]

Replaced the solenoids and fixed the problem!!! Smooth shifting now

[Costee]

Replaced the solenoids and fixed the problem!!! Smooth shifting now

How nice. Good you didn't have to go through the TCM trauma.
PS. Could you provide a link to the source of the solenoids. I only know of Rostra.
Thanks.