Hello All,

I am new here (sorry I skipped the introduction forum). I have a very neglected, but never abused 1990 300ZX 2+2 Auto with 113K miles. I drive it quite frequently and all I have done to date is replace the fuel filter, do a fuel system cleaning, changed the oil and added Mobil high mileage synthetic and had a trans service performed. Last week while driving the car at about 60MPH, it shifted out of lockup and into third gear. As you know, this blows because in an auto car that means you are now doing 3600 RPMs. This is when I sent her to Nissan for a trans service. Well, now the car shifts like new, but still has it's where it will downshift back into third. It is random, but happens every day. Sometimes when I am turning at speed like an off ramp and sometimes after I have driven the car for a while and leave the store. It's random at best. It can't be the trans itself (I am wrong more than not..lol). Could this be a simple ground issue? Or a solenoid? I thought I'd ask before I spent money to see if anyone has had this problem. The car is 20 years old and replacing the old wires with a new grounding kit seems like a needed addition regardless of weather that is the problem or not. If you had similar symptoms, what was your fix?

Thanks,

William

Mine used to just shift out of overdrive while at about 45 mph, but not that often. Eventually reverse went out (usually the 1st thing to go on the autos), and I got it rebuilt. Hasn't done it since. You should try changing the trans fluid and internal filter, as the reason mine went out was a buildup in the filter restricting flow to the torque converter. Hope this helps!

Oh, and welcome to NICO!

Thanks Ace,

I had Nissan perform the trans service and change the filter screen the day the problem started and the shifting on the car is excellent until this problem starts. Sometimes, I can park the car for a couple minutes and it goes back to normal. Also, when it goes back into third, it won't shift any lower than 3rd either. Temperature does not affect the problem, it has done it both hot and cold. This is why I'm thinking it's something electrical.

William