Disabling overdrive
Thread Starter
Intermediate
Joined: Oct 2017
Posts: 41
Likes: 1
Disabling overdrive
I have a new to me 87 coupe that I'm trying to get sorted out. Is it possible to disable the overdrive function easily? I live in a mountainous area and don't need OD 99% of the time. Can I just disconnect the relay or is it more involved than that?
Burning Brakes
Joined: Oct 2010
Posts: 1,037
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From: Montclair New Jersey
The easiest way would be not to put the car in the overdrive gear. Put it in "D" not the "D" with the box around it. Or you can hook up a switch from the brake pedal light under the dash. There is a write up on which wires you need to splice in. Just do a search it will come up.
Good Luck
Good Luck
Thread Starter
Intermediate
Joined: Oct 2017
Posts: 41
Likes: 1
The easiest way would be not to put the car in the overdrive gear. Put it in "D" not the "D" with the box around it. Or you can hook up a switch from the brake pedal light under the dash. There is a write up on which wires you need to splice in. Just do a search it will come up.
Good Luck
Good Luck
It's a 4+3 manual transmission, it goes into OD automatically when shifting into 2nd gear on up. The manual OD off switch in the shifter apparently is not working.
Race Director
Joined: Apr 2003
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From: moraga ca
The od on a 4+3 is controlled by a grounded wire from the ecm, through the console switch, to a solenoid on the od unit in the tranny. I could be wrong and it could be a hot wire. Look in the FSM for that wire coming out of the ecm or into the tranny and snip it to eliminate od. When I was running a 4+3, I rewired the console switch and used the od as a fifth gear on the freeway, never around town.
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The od on a 4+3 is controlled by a grounded wire from the ecm, through the console switch, to a solenoid on the od unit in the tranny. I could be wrong and it could be a hot wire. Look in the FSM for that wire coming out of the ecm or into the tranny and snip it to eliminate od. When I was running a 4+3, I rewired the console switch and used the od as a fifth gear on the freeway, never around town.
Last edited by Ray Quayle; Nov 14, 2017 at 01:08 AM.
Race Director
Joined: Apr 2003
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From: moraga ca
On the OP’s ‘87, the OD switch in the shifter is a momentary contact switch that is connected to the ECM. The pulse when pushed tells the ECM to switch the OD. On to off or off to on, assuming OD on conditions are met. It can also be pressed at startup to tell the ECM, I want manual control. To completely disable the OD, disconnect at OD or remove the OD relay on the firewall next to the fuel pump relay. I would just get in the habit of pressing the OD button after each start. That will keep the ECM from turning the OD on until you press the button again.
- 1986 Original Owner -
Joined: Apr 1999
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From: North Yorkshire, England
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