Overdrive will not engage

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.

no country told
no engine told
no vin told
these facts lets helper now the exact transmission there. which I go GENERIC answering now.
fails hot and cold engine.???
PRNDL , R and L work ok?
no BORA here at all USA.
all our cars here 2002 are electronically shifted
and the tests on car are mostly the same
as other poster said fluid levels but also not smells burnt or looks like tar.
A/t box filter not clogged. if is may work hot trans.
all fuses checked good as in ALL
no tranny leaks end to end.
engine has full power, Low and REVERSE? not told
drive never hits, 4th gear, so that can be simple.
WE next scan the PCM(tcm) and see if there are solenoid, or pressure sensor or pressure control valve errors.
if all that pans out (means good)
we then do the transmission pump pressure port tests.
in all gears PRNDL , per service manual (a tool)

also some cars this old , not here.
still had TV cables (throttle body to tranny cable)]
that if rusty, stuck or frayed they can stick out and
4th gear can not be reached because the tranny thinks the driver is wanting passing gear. 3rd.!!!


on newer boxes the TV cable is gone forever.
and TCM computes load and throttle demand purely by electronics. so if sensor lie so must box fail.

I answer for doing tests not guessing
but no transmission told. or country
some of these cars use ZF box.
maker.

1. ransmission fluid: Low or dirty transmission fluid can cause a range of transmission issues, including loss of reverse and overdrive. Check the transmission fluid level and condition, and consider flushing and replacing the fluid if it is dirty or low.
2. Transmission filter: A clogged transmission filter can restrict the flow of fluid through the transmission and cause issues with reverse and overdrive. Consider replacing the transmission filter and flushing the fluid to see if this resolves the issue.
3. Shift solenoid: The shift solenoid is responsible for controlling the flow of fluid through the transmission to engage different gears. If the solenoid is faulty or damaged, it can cause issues with reverse and overdrive. Consider having the shift solenoid tested and replaced if necessary.
4. Valve body: The valve body is a complex component within the transmission that helps to control the flow of fluid and engage different gears. If the valve body is damaged or worn, it can cause issues with reverse and overdrive. Consider having the valve body inspected and replaced if necessary.
5. Internal transmission damage: If none of the above issues resolve the problem, there may be internal damage within the transmission that is causing the loss of reverse and overdrive. In this case, it may be necessary to have the transmission rebuilt or replaced.

It's important to address these issues promptly to prevent further damage to the transmission or other components in your Chevy Silverado

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.

normally most overdrives wont work unless proper fluid levels are maintained..check fluid level on stick and add to full..if still having issues, replace filter in trans pan and refill to full.if still having issue time to replace..good luck

first thing to check is transmission oil level and quality. If that is fine than your looking at either a valve body problem (valve body is what controls the selection of gears) or possibly a problem with the bands on the planetary gear set, they can be tightened in certain models. However i dont think it is the bands.
Does the overdrive only engage 4th gear? or does it feel like the gear ratios are different between overdrive and normal before the problem happened? some overdrive buttons engage final gear and some do as much as change gear ratios like in a cvt (contantly variable transmission) and some just change the timing in the gear changes to provide more rpm/power.
My best guess is that the valve controlling the overdrive in the valve body has failed and therefor you dont get a response from the transmission (i.e no gear shifting when overdrive is selected)

4th gear failure is a common problem with this transmission, assuming it is an automatic. You should have the vehicle checked for codes by a qualified repair center with the proper scan tool. Also, check fluid level and condition. More often than not, the trans loses 3rd and 4th gear, as these are working off the same set of clutches. 3-4 clutches apply in 3rd, and when the 4th shift is made the 2-4 band applies giving you overdrive. If you have no engine braking in manual 3rd, you definitely have a mechanical failure, no 4th could be an electrical, or mechanical fault.

Check your transmission fluid level and/or have the fluid changed. If problem persist have a transmission professional at a dealership or transmission shop service it.

First thing to do is check the fluid level if that ok you may want to think about having the transmission filter and fluid changed, there are other possibilities but check these first

There isn't anything wrong with your car. This is perfectly normal. I have a 2000 ES300 as well as other people that I know and it operates in the same way. Overdrive doesn't mean the same thing for every car or transmission. In our case overdrive is simply a reference to the top gear which is 4th gear. When you switch overdrive off(which is depressing the button causing the O/D OFF dash light to illuminate,) the highest gear becomes 3rd because you turned 4th gear or overdrive off. The application scenario for this is usually mountainous terrain where a lot of uphill driving makes it more feasible not to up shift into 4th gear while ascending and descending. It will not switch back to overdrive or 4th gear until you re-engage it by turning the overdrive back on or repressing the button. Again, when the O/D OFF dash light is illuminated, overdrive which is 4th gear is off and the highest gear will then become 3rd. It will never shift into 4th gear while this light is illuminated or overdrive is off. When you press the button and the O/D OFF dash light is NOT illuminated overdrive is on and therefore it will shift into 4th gear as usual. This applies to all 97-2001 ES300's and probably any other car you drive tat exhibits this same type of change when overdrive is turned off.