Toyota 1999 overdrive

Last week, I noticed that the light for my “O/D off” was no longer lighting up when I pushed the button to toggle it.

Well… neither is the light for “D” - as of two months ago. The other shifter lights (P. R, 2, & 1) do work. It would be simple to just say that it’s time to pull the cluster and replace both bulbs. Actually, I would replace ALL of them while I’ve gone to the trouble of pulling the cluster. After 21 years, all these bulbs are on borrowed time.

But maybe this isn’t just a dead bulb?

Now, when I push the button to toggle O/D on or off, I don’t see a change in RPM on the tach at a steady highway speed on level ground . So regardless of the light, it’s clear that nothing is changing when I toggle the button controlling the overdrive. Unfortunately, I never paid enough attention to tach vs speedometer to know what RPM I should have at a given speed with O/D on. My hunch though is that O/D is currently ON.

A few weeks prior to noticing this problem, I did turn off the O/D to help with braking when was towing a relatively heavy trailer into a river canyon, so I know that the warning light was working then.

I assume that a dead bulb would not affect the functionality of the toggle button. Am I right on that?

If I am, then I have to presume some other electronic problem has occurred, maybe just that the switch has failed. Are there any ways to test the switch? I have a continuity tester light, so where would I go to access whatever wiring supplies the switch? Could this be controlled by a fuse? Or has something more complicated happened with the electronics controlling the O/D, or the transmission itself?

Is there anything obvious that I’m missing here?

Thanks for any help.

Do you have a CEL lit on the dash? If so I believe it was a P07xx code that drove a close friend of mine to buy a new shift solenoid pack for his 99’ Camry V6. It had a 7 something code related to the O/D solenoid functionality. It became a major problem because the cars complaint about O/D actually lit the CEL which prevented him from getting inspected. So I replaced the solenoid pack under the trans pan. He was told not to try and target the solenoid in question because as you replace one…the others start to go in succession so I replaced the whole thing at once. Problem solved.

His did not present with the same symptoms as yours with the indicated gear selected lights going out. That function is closely related to the shift switch on the trans shift arm and also the bulbs in the dash… so maybe you need to start there. If you get any kind of P07xx codes…it will be that solenoid pack (a 3-400 dollar item) and a fairly easy swap out. You get to change the trans filter and fluid also, so its a multi win type of deal.

I also owned a 1999 Corolla before switching to my current 2012.Although I never encounter your situation in the 20 years I owned the car, I noticed that the rpm was slightly lower with OD activated,resulting in a slight gain in fuel economy on the highway.To me, its not worth spending money on this 21 year old car just to save a drop of gas…the math makes no sense.

Thanks Blackbird, I appreciate the details you offered.

No, there’s no CEL.

the same symptoms as yours with the indicated gear selected lights going out.

No again. As I wrote, the other shift selector lights work, except for D, which had been out for at least a month prior to this. I hadn’t even thought of that as related, but maybe the D light is indeed part of this.


I noticed that the rpm was slightly lower with OD activated

Right, that’s the whole point of overdrive, reduce RPM to save fuel.

I agree that this is not worth a big repair bill, but if it’s something I can troubleshoot and solve with a bit of my own effort, then probably worthwhile. It is useful for the very situation where I used it - compression braking before going to a lower gear, but not worth big bucks as you said.