Ok, I just got my transmission rebuilt and had a HUGE transmission cooler installed, but I want to know exactly how well this transmission cooler is working so I have purchased a transmission temperature gauge from AutoMeter. The guy at the transmission shop tells me that I could splice the wire from the TOT (Transmission Oil Temperature) sensor to the TCM (Transmission Control Module). However, I am pretty sure that the calibration of the TOT sensor is different from that of the the AutoMeter gauge. Does anyone know how I could get this to function correctly?


Also, I have noticed since I had my tranny rebuilt that my O/D Off light flashes for a while each time I start it, but only after it has been driven the last time. And also the shift pattern since I had it rebuilt is greatly different than it was before. I fear the lack of my locking torque converter at low speeds will kill my gas mileage.

The old shift pattern:
1st gear
2nd gear (about 5-10 MPH)
3rd gear (about 20-30 MPH)
Lockup Torque Convertor engauges (20-30 MPH)
Overdrive engauges (about 35 MPH)

The new shift pattern (first set of shifts):
1st gear
2nd gear (2500 RPM regardless of MPH)
3rd gear (same as old pattern)
Overdrive engauges (30-40 MPH)
Lockup Torque Converter engauges (45-50 MPH)

The new shift pattern (2nd and later set of shifts):
Same as old shift pattern but the Lockup Torque Converter does not lock until 45-50 MPH

Any help with these two issues will be greatly appreciated.

 

Install your own temp sensor, don't rely on the stock one. IIRC it's just like the stock coolant temp gauge, cold/normal/overheating, rather than an accurate temperature sensor. Tapping into the circuit could also affect the readings the TCM receives.

Have you checked the trans codes yet?

If OD is engaged, the torque converter will not lock up in 3rd gear, only 4th. If you have OD disabled, then it will lock in 3rd.

 

Ok I understand why you would say that but how should I go about installing this? Should I install it on the cooler line or somewhere else? A guy with an online tutorial suggests that you should drill a hole in your transmission pan and install it there, but in my opinion that is a terrible idea due to leaks, inaccurate readings due to that not being where most of the heat is, etc... If on the cooler, should I install it at the output to transmission cooler or should I install it at the input from cooler? Also, should I install it on the transmission end of the hose or the cooler end of the hose?

I have no consultII tool and for ages I had a broken O/D off switch so I had no way of checking the trans codes, but the guy at the shop used "Modis" to scan the consultII port and it gave a VSS code at first, then he replaced the VSS, but the code came back, and also another code came "ECM<->TCM dataline". He told me that might go away after a week or so, maybe the transmission failure caused them to get out of sync or something.

Well I can see why that should be the case, but for some reason from 80,000 miles (the time I got the car) to 147,000 miles (when I had the tranny rebuilt) it always:
1. Locked up the TC in 3rd with O/D on
2. Shifted to 4th WITHOUT unlocking the TC
3. Locked up the TC in O/D between 30 and 40 MPH
4. Stayed locked up till it downshifts, the brakes are applied, or heavy acceleration occurs
5. Shifted the same every time given the same acceleration.
6. Had no O/D Off light flashing.

But now it always:
1. Locks up TC only in 4th when O/D is on
2. Locks up TC in 3rd ONLY when O/D is off
3. NEVER locks the TC under 45 MPH even if I maintain constant speed
4. Unlocks the TC when the throttle is released even if the brakes are not applied.
5. Stays in 1st for too long on the first set of shifts after starting but shifts out of 1st at normal time after that.
6. Has a flashing O/D Off light upon starting, but only if the last time it ran it shifted into at least 2nd.

 

The TC will only lock in 4th gear. IF OD-OFF is selected then you have a 3 speed automatic with no locking TC.

The TC will lock over 40MPH as long as the tranny temp is up to normal operating conditions. Depressing the brake or heavy accelleration will unlock it.

Your shifting points seem normal to me, I don't see how your TC would lock in 3rd gear, the TCM isn't programmed to do that.

The flashing OD light should be looked into, perhaps go to the tranny shop that did the work or check the tranny codes yourself.

 

Ok, as I said before, after the rebuild it only locks after 40 MPH, but before the rebuild, it always locked between 30 and 40 MPH (usually about 35). I dont think this was anything wrong with it because it did this from 2005 to 2009 (from the first day I drove it) and from 80k miles to 147k miles. Even the FSM says it is supposed to lock the TC between 30 and 40 MPH. Also, as you said, depressing the brake or heavy acceleration should unlock it, it does, but for some reason simply releasing the throttle also does now, but it did not before the rebuild. Anyway, the main things I am concerned with right now are the 1-2 shift pattern and the O/D off flashing and codes.

The problem I have with the 1-2 shift pattern is that for some reason after the rebuild it will only shift into 2nd gear after the engine reaches 2200 to 2500 RPM even with lightfooted acceleration, BUT after accelerating for the first time since starting it, every time after that it does normal, until you turn it off and restart it again.

The problem with the O/D Off light is that it is flashing for a few seconds when I first start it, which simply tells that I have codes from my TCM.

And as I said before the codes I am getting are:

VSS Sensor fault
ECM<->TCM data line fault

The VSS sensor has already been replaced, but the code came back after clearing

The transmission shop tells me that if any codes exist, then the shift pattern may be altered and adaptive learning mode may be canceled and it may go to the default shift patterns and ignore some feedback data lines.

The strange thing about it is that none of these codes or different shift patterns existed until after the transmission rebuild.

Also, I finally got the transmission temperature gauge. The instructions say the same as that online tutorial, that is to drill a hole in the pan and place the sending unit there, but I am skeptical of this idea because:

1. I fear that might cause a leak, or possiblly some welding residue might come loose and ruin the transmission

2. The pan is outside of the area where most of the flow of fluid is and I think maybe there would be an innacurate or delayed reading at this point.

3. I fear that drilling on my oil pan might void the warranty on my transmission rebuild

I feel that putting the sending unit in the output line to the cooler would be a much better idea if this is possible. Anyone have any thoughts about this idea?

Still alot of work I have to do on this car but not exactly sure what to do or how I should do it.

I will keep you updated on the codes I find and if any shift patterns change.

 

The TC will lock up in third if OD is off:


OP: how long ago was the trans rebuilt? If you have questions or concerns, why not bring it back to the shop that did the work?

 

Interesting - I've never had my TC lock with OD off, even on the highway.
Where did you get that table from?
4th gens don't have the comfort and power switch.
4th gens don't have shift range D3 or D4 either.
I think the owners manual specifies the OD OFF mode as well with no locking TC.
Are you looking at a 3rd gen shift table? That car had those tranny modes if I'm not mistaken.

 

Nope, that's from the A32 FSM. It's specified the same way for the A33, IIRC. Just another case of Nissan not bothering to reword things, I guess.

 

Have been communicating with the shop on nearly a daily basis. That is how I am getting the codes, but they just keep telling me to give it a week or two and maybe it will fix it's self, then the guy adds "Unless you feel like tearing your whole dashboard out." I dont know why, but for some reason, every since the transmission failed, the TCM has been doing wierd things. At first the guy at the transmission shop suggested that it is probably just in Adaptive Learning Mode, but then I noticed the flashing O/D Off light and since then I have been unable to find a solution. I dont know why, but for some reason when the transmission failed, it seems to have "confused" the TCM and caused the shift patterns to change and some codes to appear that I cant seem to get to go away now.

BTW, I got the transmission rebuilt a little over a week ago.

 

The A32 doesn't have any sort of adaptive shift controls. As you can see from the table above, the shift points are pretty much statically set. They'll change a bit based on coolant temp, throttle position and engine speed of course, but they shouldn't change at all otherwise.

What were the exact codes again? Flash count, not your description.

Another easy thing to try is make sure the connections on the trans are all clean and tight, no corrosion or anything in there.

 

as far as an oil temp guage, just use the sending unit that comes with the guage, I believe you can screw it into the tranny case by the oil pan, or tap in to the line thats coming out of the tranny to see what temps it sees before it gets cooled off by the radiator.

As far as the tranny codes go, we need the exact codes before we can point you in the right direction. It might very well be your tranny computer acting up, even though the 4th gens are not prone to TCM failure, some 5th gens are, so you never know. Are you taking it easy on the rebuild? You can't abuse it for at least 1-2k miles. Have to give the internals time to wear a bit.

 

Not sure the flash count, not really sure how to do that with the TCM, the only way I know how to get a flash count is with the ECM/MIL, I have been giving you the codes the transmission shop tells me I have. As I said, I have a huge transmission cooler now, so maybe it is overcooling? I dont know yet because I havent installed the gauge yet.

Where is there a place to screw it into the transmission case? I hope there is no drilling involved in this because I fear voiding the warranty, or even worse, damaging something inside. I was thinking maybe installing the sending unit in a place where it sees the temp just before cooling would be the best bet, maybe somewhere inline with the cooler in a T joint or something. After it is broke in, I will probably be pusing this transmission to it's limit quite a bit so I need to know the temp at all times, not with a 1-2 minute convection current delay caused by the sending unit being outside of the main flow area. And yes I am taking it easy. I will research the org a little to see if I can find how to get the exact flash codes as I have not been doing that myself, the transmission shop has been getting that through the consultII port with a "Modis" and telling me the description, not the codes.

I will keep you guys updated.

 

Here are the diagnostic steps:


Going from the trans shop to you to us is just going to cause a lot of confusion. You are driving the car, correct? Why not just pull the codes yourself?

 

Makes since to me! I have already started the car with O/D off, waiting for it to warm up. Will get back with you soon.

 

Ok, I tried it, but there is a problem. In the instructions you gave me it says:

Turn ignition switch ON (do not start)
Move selector to D
set overdrive OFF
turn ignition ON

It never said to turn it off. Because of this error I am unable to make this work. Do you know when between these steps I am supposed to turn it off?

 

your tranny is not rebuilt properly and it will fail again, probably after warranty expires.
i've had bad experiences with rebuilt units including flashing od lite at start up, weird shifting etc., until i went with a low milage used factory tranny.
my advice: get it diagnosed somewhere else.

 

This transmission shop is the oldest, most experienced shop in town, and the guys who work there have lots of awards from colleges they have been to every year, the Better Business Bureau even gives them good feedback and says they are recommended.

Does anyone know anything about the error in the diagnostic procedure yet?

 

Ok I have an update.

The man at the transmission shop suspects my revolution sensor is bad because he replaced the VSS but the code came back and he says that is almost the only thing that should cause that without making my speedometer glitch. He says also there was a recall or something on the TCM wiring harness and it was never replaced with the updated one. Also, he says the A/C evaporator coil in 4th gens tends to leak water onto the TCM and he says my TCM appears to be very dirty which could suggest that mine has this problem and maybe my TCM needs to be replaced because it may have got wet over the years.

I will take my car back to the transmission shop at 10:00 tomorrow and they will replace the revolution sensor. Then maybe it will be better.

But I can tell you that something is definately still wrong because it sometimes drops into failsafe for no known reason, and even one time it kept shifting between O/D and 3rd over and over just before dropping into failsafe.

I hope the new rev sensor fixes this.

 

a/c evap is nowhere near tcm, but let us know if they resolve this.