Nissan Repair: Overdrive doesnt work, brake light switch, nissan altima

Question
Hello Bill,
I have a 1997 Nissan Altima GXE, automatic, 4 cyl, 2.4L with 253,000 miles. For the last 6 months the overdrive hasn't been working. At the time it had stopped working I had the brake light switch replaced.
I had the fuses checked and they're ok. The transmission seems to be working fine, no slipping or anything unusual, just the overdrive doesn't work. Any ideas what it could be? Also, is it ok to drive the car without the overdrive? I do only local driving, no interstates at 55 mph. Thank you.

Answer
Hi there, first let's make sure that the TV cable, (Throttle Valve Cable ) is properly adjusted. If it's too tight, the transmission thinks that is on passing gear and it will stay on 3rd gear (D). When you engage o/d, the ECM grounds the torque solenoid wich in turn locks the torque converter and it will turn with the same RPM as the motor's. (You will see the tach RPM drop). So we will need to find out if the ground cable is working properly and it is not open or broken between the ECM and the solenoid and also to find out if the ECM, (Electronic Control Module-the computer) is actually trying to ground the torque solenoid. I understand that these tests cannot be performed by a person that has no previous experience on troubleshooting, that is why I recommend a look at the problem by a qualified technician. It is perfectly alright to drive the car locally without overdrive and in stop-go-passing situations. The overdrive helps save on fuel on the highway and under light load, as the motor does not have to work so hard.