PTNR

iTrader: (2)

The other day my car temp was getting hotter than normal (AC on) and while driving on the highway going up a hill the car downshifted out of overdrive to get up the hill. when i got over the crest, it would not shift back. the tranny was stuck without OD.

Now, this had happened to me a long time ago and i was told by the dealer that the computer somehow misreads the situation and all you need to do is shut the car off and it will reset and work ok. i tried it back then and also this time and it was true. However, this time it happened again right after getting back on the highway (temp was still hotter than normal). so i got off once again and turned off the car. restarted in 5 minutes and noticed the OD light blinked a few times after starting the car. i went back on the highway without the ac on (temp was normal) and the tranny was fine.

It seems the car is getting too hot with the ac on and if the tranny downshifts alot for hills.

any ideas on what the problem could be? fluid? radiator?

what does the blinking OD light signify?

thanks for any help.

OhOhMax

iTrader: (2)

The OD light always blinks when you start the car. You most likely just never noticed it until you started having this problem.

NiSmOVQ35

iTrader: (1)

Get a tranny cooler, my friend had the same problem with his ford, the tranny was getting to hot and acting up .. he got a nice tranny cooler solved all his problems.

Professor

iTrader: (4)

If the od light blinks for abit after the car starts, It requires service, The manual tells you about it, Something to do with the tranny electronics.
I added a cooler to my car, I havent had any probs to date.

PTNR

iTrader: (2)

my OD light does not blink when i start the car. It turns on once with all the other idiot lights on the instrument panel while starting the car and then goes off with all the other lights but it does not blink.

the only time it did blink was when the car was hot and i lost overdrive and i turned it off to reset it. it blinked 2 or 3 times at that point but now it does not blink.

PTNR

iTrader: (2)

just to clarify, does this mean you had the same problem and you fixed it by adding the cooler?

Professor

iTrader: (4)

I havent had the problem that you mentioned, But during the winter i would notice the light would flash for awhile rapidly after i start the car and all the other lights go it it stayed blinking longer. The manual said about service when it did that, Its only done it 3 times in the cold, i havent seen it happen since it got warmer out, Also the cooler with the addition of Lube Gard has given me smoother shifts.

Trurida18

iTrader: (4)

is there great Significance to adding a tranny cooler?

Torgus

iTrader: (10)

a hayden 404 should drop the avg temp by 70F.
Now they are supposed to operate at a certain temp but adding a cooler can't hurt had one on my 4th gen and it never gave me problems...i installed it because of the stage 2 vb mod.

another thing to consider is possibly your stock tranny cooler is getting filled with crude and not cooling the liquid well.

if adding an after market one i would suggest not using the stock cooler unless you 1st blow it out with high pressure to make sure it is REALLY clear on any blockage.

jakesI30

I have this same problem, except is was so bad that it would downshift to 2nd, then not upshift at all, I would pull over turn off car, wait a few minutes and all would be okay, until next hill. I was also getting a ses code of P0720, i changed the vehicle speed sensor (located in trans, behind drivers side tire), 10 minute job, all is well so far. My next move is to install a cooler, just for insurance

OhOhMax

iTrader: (2)

Well then maybe my car is just weird... I've put ~80K miles on my maxima since I got it 3 years ago and it has always blinked for about 2 seconds while the car starts and no problems for me.

PTNR

iTrader: (2)

did you access it from above or below? if it's only a 10 minute job, then i'll want to try this. any pics of the actual location of the sensor?

were the ses light and the tranny problems happening at the same time?
did you have any issues with the car temp running hot?

i have to get to the bottom of the overheating issue. this is what i feel is causing the tranny to have the issue with the OD. It never happened until the engine got hot. The extra load up hills and with AC is making ithe car run hot. got to be a coolant problem or maybe blockage of some kind.


to those who added tranny coolers, did you have the coolant temp gage running hot and that's what prompted you to get the tranny cooler?

808MAX-SPEC

iTrader: (7)

Yesterday I purchased the B&M tranny cooler. I'm hoping to get it installed before the end of the week. Recently my trans has been slipping when I'm on the road for more than an hour in stop and go traffic. Not sure if it's the recent hot weather but I hoping the trans cooler will help.

jakesI30

i pulled drivers side tire, then the inner fender shield, the VSS is located, on the top of the trans,and is held in place with a 10mm, bolt,and a wire connector, put a little oil on the o ring,,slip it in,rebolt there ya go

BlackBIRDVQ

iTrader: (15)

So what good does this tranny cooler do you, when you have a problem with the AC being on ?

Before you spend $$$ on a tranny cooler, you should CLEAN out your radiator and AC condenser. What happens is they are both radiators, AC condenser is HOT when you touch it. Its a heat exchanger / radiator, and it needs airflow to cool it of. Ever notice your AC works better when the car is moving vs bumper to bumper traffic ? Its all bout the airflow....

When the airflow is compromised due to debris on the condenser and what not..... there is no airflow going through the radiator. Radiator sits BEHIND the condenser and has fans attached to it. By default they will not turn on, unless you are going less than 35MPH (some are more some are less speed) because the ECU thinks there should be enough airflow to cool the radiator/coolant down.

So clean out your radiator, or check for airflow restriction.

Professor

iTrader: (4)

Hmm my rad fan runs full time when the ac is on, When it gets hotter, the other fan kicks on, it sounds like a jet turbine when both are going on high speed, it seems they have 2 speeds.Even when iam going 70mph the fans are on.

BlackBIRDVQ

iTrader: (15)

You got a problem then, they are not supposed to be on at 70MPH. ECU tells em not to turn on till the speed is below certain speed- around 45.

Bufflomike

I am assuming the heat has put the trans into a safe mode since running your transmission in OD while very hot may cause excessive wear to the friction discs. I worked in a tranny shop for 8 years and we would see some trannies wiped out by towing uphill in OD. I have also seen a 5th gear weld itself to the shaft many times due to excessive heat.

SuperStasiu

iTrader: (3)

How about just changing your tranny fluid on a regular basis and also check the level of your tranny fluid if its not shifting into gear or wont go back into overdrive could be due to low fluid levels?

PTNR

iTrader: (2)

my tranny fluid is good and i also think that the excessive heat made the tranny come out of OD. i also agree with the fact that obstructions will kill the airflow. i will check for any obstructions tonight.

jakesI30 - thanks for the info on how to change the sensor.

BlackBIRDVQ,

if i check and there are no obstructions, what else could be causing the car to run hot? should i change the coolant and flush? i know the coolant level is good and it was changed and flushed about 3 years ago at the dealer.

BlackBIRDVQ

iTrader: (15)

You are not supposed to flush your coolant every 3 years... its supposed to be done more often. I change mine 2 times a year, its not expensive and its easy to do it yourself.

If you continue doing 3 year coolant flushes... at this rate you will be needing a water pump in about 2-3 years. Only reason they start to leak is because of lack of maintenance.

Tranny shift points are based on throttle, engine temp, load on engine and speed. If the coolant temp gets too hot, TCM goes into safe / limp mode.

Before you do any kind of tranny coolers and other not needed BS, you should really start looking at maintenance side of things... like cooling system condition.

foodmanry

iTrader: (15)

PTNR...my 2k auto exhibited the same thing, but I was not having any cooling issues. In fact my cooling has been excellent. But the tranny would kick out of OD going up a long hill and not go back into OD on the down hill. It did this 3 times and two of those times I just shut the car off and turned it back on to reset and it worked. The third time I had to let the tranny cool down and actually did this by pouring water on it for a few minutes. It was fine after that.

I installed a tranny cooler a few years back after getting VB mod and have traveled up and down the same hill I experienced issues with before. I haven't had an issues since the tranny cooler install.

I do agree with BlackBird...get your cooling system maintained and working efficiently then monitor the situation before doing anything. You really shouldn't need a tranny cooler unless you have a modified tranny (VB mod).

PTNR

iTrader: (2)

thanks for all the info guys. i will change my coolant and flush ASAP. i'll let you know if all is well.

PTNR

iTrader: (2)

flushed and changed coolant.

All was ok for several days then one hot day in traffic with the AC on, the temp started creeping up again. I cut off the AC and the temp dropped back to normal. Cut the AC back on and within a few minutes it creeps up once again. This only happened on this one hot (85) day since i changed the coolant but the rest of the time it seems fine.

Anything else to check?

BlackBIRDVQ

iTrader: (15)

See post #15.

Radiator flow blockage.

Professor

iTrader: (4)

Problem solved, was a bad tempswitch/sender thingy lol

PTNR

iTrader: (2)

i checked and there is no blockage of air flow. maybe inside the radiator? but i had it flushed....?

NJYTHRD

hmmmmmmmmm

BlackBIRDVQ

iTrader: (15)

Did you check for accumulated dirt between the CONDENSER and RADIATOR ? Z32 300ZX are VERY notorious for dirt between the 2 and the car will start to overheat as soon as the AC will be kicked on.

You need to check that out. Condenser gets hot during AC operation as its used for radiating the expanding gases (which get HOT) inside the AC system. I don't want to get into the HOW the AC system works, but the system has 2 sides- HOT and COLD side, and condenser is on the hot side. When that condenser gets hot, and there is junk between IT and the engine radiator- the engine starts to overheat. Thats why your problem is ONLY when the AC is on - blockage to the radiator.

Does that make any sense ?

nismopc

iTrader: (3)

Weaksauce. No content. Great post!

PTNR

iTrader: (2)

makes perfect sense. any tips on how to access the area in between? i did not check there and i'm not sure how to get at it. i'll have to look at it closely. thanks for the info.

BlackBIRDVQ

iTrader: (15)

You can remove the radiator hold downs that are on TOP of the radiator support and then you can gently push the radiator TOWARDS the motor. This should open up more room between the condenser and the radiator.

Get a medium pressure- pressure washer and gently clean it- trying to avoid hitting the condenser and radiator with high pressure water as much as you can.

Bent up fins on radiator don't flow too well.... You could also try a Shop Vac with a slim adapter to suck all that dirt out.

Reizy

iTrader: (48)

PTNR, I have the same problem. My 02 gets hot going up hills or with the ac on. Ive never had it to the point where it kicked me out of overdrive. Ill pull over when the temp gets way up there, I dont think its healthy running my engine that hot.

I started troubleshooting this with a coolant flush. Did everything recomended on the org, flush with 10 gallons of distilled and finished off with a gallon of Toyota red. Didnt make a difference. Next I went to the thermostat. A $12 part and easy swap that I was hoping would fix it. Nope. Like you, Im running out of options. The flow through the radiator is good, the heater core seems to put out lots of good heat. I assume the fins on the pump are good and pushing water as I get good heat and coolant flows out of the radiator with the cap off when rev'ed up. The fans come on when they are supposed to. The radiator cap is good. My best guesses are air bubbles in the system (which I would think would work themselves out to the expansion tank after a few drives), too much friction in the cylinders increasing temps, or added heat transfer from the oil cooler and stock tranny cooler? Let me know if you get any resolution or if anyone has a solution.

raybone97-I30t

iTrader: (1)

i had that problem, i took it to a dealer (before my .org days), they replaced the thermostat and it was fixed. worth a try.

PTNR

iTrader: (2)

well, now that it got hot outside again...

for the first time since i posted last year, it popped out of OD while running hot once again. it seems to be only when the temps are extreme.

to those who had similar problems, has anyone ever found an answer?

808MAX-SPEC

iTrader: (7)

I took BalckbirdVQ's advice and cleaned the radiator and AC condenser. Trans slips were less frequent so I held off on the installing the cooler. However, I experience a major slip yesterday so I'm going to clean the radiator and condenser again, flush the fluid and install the cooler. Can't believe almost a year went by.

Scottwax

iTrader: (8)

If your car is actually running hot (as in the temperature gauge reads higher than normal), you have a problem with your cooling system. If the cooling system hasn't been properly flushed (not just drain and fill) in a while, start there. Make sure the thermostat and cooling fans are working properly. Check for obstructions in front of the radiator/condensor and also in between the two. You find the cooling problem, you should fix your transmission problem too.

PTNR

iTrader: (2)

that's exactly what i am thinking but i tried almost everything you mentioned and still had a problem last year and now that its hot outside, again this year. flushed, checked for obstructions and found none, fans working as they should. i did not replace the thermostat and i'm thinking maybe the radiator could be an issue. i have 185k on this car.

any ideas?

pinakbet

My car exhibited the same problems as you describe. I also initially thought it was something to do with the heat. The longer I drove, the more prone it was to slipping out of gear and the engine revving high.

I'd pull over to let the car cool, and I noticed the O/D light blinking as soon as I restarted it. You're supposed to be able to tell what the problem is according to the blink pattern. Sorry I don't have a link.

After a while, the car finally threw a PO720 code. Vehicle speed sensor. I replaced it, and the problem has since been gone. Incidentally before I installed the new sensor I had also put in a trans cooler. This only delayed the problem exhibiting itself during a drive.

Here's a link that helped a lot:
http://picasaweb.google.com/cefiro.calsonic

Find a OBDII scanner and get latent codes pulled even if there's no SES light.

Hope this helps, good luck!

Scottwax

iTrader: (8)

Could need a new radiator with that many miles. You can find them online for $135-150. About an hour to replace.