Overdrive

[95nismo240]

The car is a 95 240sx auto. when i turn overdrive off while driving the rpms dont change or anything, but the overdrive light is turning on. so basically myu overdrive doesnt work. what can cause this??? is it something electrical??

[NISTECH]

First make sure your fluid level is correct. You check your fluid when the engine is warmed up and running. Also the trans wont go into over drive till the trans reaches operating temp.

[NISTECH]

if this isnt the problem you may have a split or leaking seal in the 4th apply portion of the band servo.

[95nismo240]

my fluid is at the right level and i tried it while the transmission was at normal operating temperature. still nothing changes!! what does a split or leaking seal in the 4th apply portion of the band servo mean?? my transmission shifts perfect and strong so i dont know why i would have a problem with the overdrive.

[s13sr20chris]

default is to have od onpress button and get od off(hence the light)your saying with od on(no light) you never get into 4th gear?

[95nismo240]

i know overdrive is always on... i have 4 th gear but the problem is that i cant turn it off. when i push the button the overdrive light comes on but the rpm level istays the same and i still og into 4th gear with it off.

[NISTECH]

well then forget my 4th apply theroy as you wouldnt have forth gear. The TCM is what turns the light on and off so the TCM knows you have turned off the switch. Gonna review the service manual to see possible why its not down shifting.

[95nismo240]

ok thnx nistech

[NISTECH]

You need to perform self diagnosis on the system to see if there are any codes stored. I will post the test proceedure a bit later if you dont know how to do it.

[benemorius]

Just to be sure - can you confirm that you do actually have 4th gear? Is it possible that you always stay in 3rd and only thought that you were in 4th?

[95nismo240]

i read the codes and it throws the park neutral switch and the inhibitor switch.

another thing is when i erase my codes and drive for about 5 min the CEL turns back on again. my CEL is always on!!

yes i do have fourth gear i know i have it for a fact. 60mph is at like 2100 rpms

[NISTECH]

bingo. I didnt mean to check for codes in the ECM. there is a procedure for getting the O/D lite to flash codes. But since you have an inhibitor switch code I believe you have found your problem. The service manual makes mention about the inhibitor switch causeing a problem with shifting. Do you have a service manual to follow the adjustment procedire for the inhibit switch?

[95nismo240]

ya i have a service manual dled onto my computer but i dont have any of the tools or a lift to do it. if i take my car to a transmission shop how much would i be expecting to pay... and would they know how to adjust it??

[NISTECH]

they will likely charge you an hour to an hour and a half to do it. Yes they will know how to do it.