# 1985 Chevrolet Corvette overdrive **URL:** \ **Category:** Maintenance/Repairs\ **Tags:** chevrolet, corvette\ **Created:** [July 9, 2018, 5:30pm UTC](https://community.cartalk.com/t/1985-chevrolet-corvette-overdrive/120715 "2018-07-09T17:30:45Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![AugustWelland](https://avatars.discourse-cdn.com/v4/letter/a/919ad9/32.png) [@AugustWelland](https://community.cartalk.com/u/AugustWelland)\ **Post date:** [July 9, 2018, 5:30pm UTC](https://community.cartalk.com/t/1985-chevrolet-corvette-overdrive/120715/1 "2018-07-09T17:30:45Z")
any info on overdrive unit electronics would be great… doesn’t engage… ---
**Author:** ![Mustangman](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/mustangman/32/44130_2.png) [@Mustangman](https://community.cartalk.com/u/Mustangman)\ **Post date:** [July 9, 2018, 8:22pm UTC](https://community.cartalk.com/t/1985-chevrolet-corvette-overdrive/120715/2 "2018-07-09T20:22:28Z")
If your car is a manual transmission - you don’t say - the overdrive is a 2 speed planetary gear set much like an automatic transmission. I had one in a '84. It pretty much was awful. If it doesn’t work, it is more likley the overdrive itself, not the electrics. You need a wiring diagram and a shop manual if you want to fiddle with this system. If I remember correctly, there wasn’t much electronics involved, just a few switches. ---
**Author:** ![Mustangman](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/mustangman/32/44130_2.png) [@Mustangman](https://community.cartalk.com/u/Mustangman)\ **Post date:** [July 9, 2018, 8:27pm UTC](https://community.cartalk.com/t/1985-chevrolet-corvette-overdrive/120715/3 "2018-07-09T20:27:03Z")
Here: Notice there is just an apply solenoid controlled by switches to the ECU to engage and disengage the overdrive. ![image](https://global.discourse-cdn.com/cartalk/original/2X/c/c5d33cc9085f795accd6b8c983a062271a99ca93.jpg) ---
**Author:** ![AugustWelland](https://avatars.discourse-cdn.com/v4/letter/a/919ad9/32.png) [@AugustWelland](https://community.cartalk.com/u/AugustWelland)\ **Post date:** [July 9, 2018, 10:55pm UTC](https://community.cartalk.com/t/1985-chevrolet-corvette-overdrive/120715/4 "2018-07-09T22:55:06Z")
Hi Mustangman… Thanks for the reply…Big Help… With appreciation, August…