Overdrive not engage - Grand Vitara Suzuki Cars & Trucks

The erratic jumping in and out of overdrive (O/D) on your 2006 Terrano 3GMR with a 3.2L engine could be caused by a few different issues. Here are some possible causes and fixes:

1. Faulty speed sensor: The speed sensor provides input to the transmission control module (TCM) to determine when to engage overdrive. A faulty sensor can cause the TCM to think the vehicle is going too slow or too fast for overdrive engagement. A mechanic can test the speed sensor and replace it if necessary.
2. Low transmission fluid level: Low transmission fluid level can cause the transmission to shift erratically or not engage overdrive. Check the transmission fluid level and add fluid as necessary. If the fluid level is low, it's important to also check for any leaks that may be causing the fluid loss.
3. Worn or damaged overdrive band: The overdrive band is responsible for engaging and disengaging overdrive. If the band is worn or damaged, it may not engage properly. A mechanic can inspect the overdrive band and replace it if necessary.
4. Transmission control module (TCM) issues: The TCM controls the shifting and engagement of overdrive. If the TCM is malfunctioning, it may not engage overdrive or cause erratic shifting. A mechanic can test the TCM and replace it if necessary.

It's recommended to have a professional mechanic diagnose and repair the issue, as the transmission is a complex and vital component of the vehicle.

Engaging your overdrive depends on the specific type of vehicle you have. Some vehicles have an automatic overdrive, which can be engaged by pressing a switch, while others have manual transmission. In these cases, the overdrive is engaged by moving the gear stick into the overdrive position. Refer to your vehicle's owner's manual for further information and guidance.

P1740 Torque Converter Clutch or Overdrive Solenoid ...

https://www.engine-codes.com > p1740

Faulty Torque Converter Clutch (TCC) and Overdrive (OD) Solenoid. ... Torque Converter Clutch (TCC) and Overdrive (OD) clutch are tested when the Powertrain Control Module (PCM) requests TCC engagement in 3rd gear and Overdrive. The P1740 code will set if expected RPM drop is not

overdrive is best used at around 60 k or around 2,500 rpm and over
using any lower only increase fuel consumption which is opposite to it's intended purpose

Overdrive engages at speeds between 40-45 mph, you should leave it on most of the time, you can disengage overdrive only when towing or going on hilly terrain

Does the car have a button on the shifter handle somewhere to disable overdrive? Also, there is a plug on the transmission that must be plugged in to engage overdrive so check to make sure it is plugged in correctly.

I have a similar problem... No overdrive.. Will only work with a computer reset...disconnect battery... then overdrive works but eventually reverts back to no overdrive.... Computer based problem... My transmission was checked fine

not usually close to the ac it is likely eithor the od button is dosconected burnt or blew a fuse

rarely is the selinoid a fault


but if you know where the selinoid is run a direct line to it using speaker wire engage it and see if it works
if it does try and track the circut failing that run a line arround it and make it manule

has the vehicle speed sensor been replaced? that is what controls when the trans shifts into od

There is an electronic sensor on the outside of the transmission.Change the filter and fluid and replace sensor.The sensor costs around $150.
"High speed" probably is over drive,so if it is turned off,it can't engage.I have found that cutting the overdrive switch on and off can cause excessive wear and tear on the overdrive. 

Regardless have the car scaned for a any codes thay is causing the problem. Just trying to keep the cost of repairs down by know exactly what the ECM has in it's memory for any malfunction that is creating your overdrive from engaging.
Good luck and hope this helps