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1985 4+3 with overdrive problem.

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Old Sep 15, 2010 | 12:07 PM
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Default 1985 4+3 with overdrive problem.

I have an 85 4+3.
Had a successfull overhaul of the gearbox. Everything worked nicely. Overdrive worked great when pushing the OD switch.
Suddenly it was not possible to enable the OD with the switch. No overdrive light showed.
Took out the relay and put 12V at the A terminal at the relay contact and the OD light came on.
Took a test drive and nothing worked. Then suddenly everything worked all right.
Assume that the connection from the relay to the OD solenoid and light is alright.

Are there any common fault with for ex OD switch ( I have the switch on the console). It was not recommended to ohm the in the direction of the ECM so do not know if there is bad connection.

Will be glad for any comment or recommendation.

This happened the first time 3 years ago.
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Old Sep 15, 2010 | 01:00 PM
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Sounds like you might have a bad or intermittant switch. Tilt the back of the console up and remove the connector to the switch. Check it with an ohmmeter. You should find it working intermittantly. Maybe spraying contact cleaner in the thing will work. Good luck.
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Old Sep 15, 2010 | 04:45 PM
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Thanks for the info. Did not think thatthe switch was bad as there are just small currents through it.

Where can I buy an early 1985 console Overdrive switch. Ecklers does not seem to have it and the same with Corvette central.
I would very much appriciate an answer where to buy it.
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Old Sep 15, 2010 | 11:46 PM
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You might find a suitable switch from a local electronic parts shop - I found the mini switch on the shifter locally for under 4 euros.
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Old Sep 15, 2010 | 11:49 PM
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Originally Posted by TheFinn
You might find a suitable switch from a local electronic parts shop - I found the mini switch on the shifter locally for under 4 euros.

'85 is only a OFF/ON switch input to ECM

See
http://www.5speeds.com/43table.htm
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Old Sep 16, 2010 | 05:52 PM
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Thanks for the info.
What I would like to have is the stock switch with the writing on it. Any places that have newaftermarket switches or even AC delco original switch?
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Old Sep 23, 2010 | 01:37 AM
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i need some help with this as well. i had my overdrive rebuilt and it doesn't work properly. nothing happens when you push the button on the shifter. but i noticed while cruising on the hwy, all of a sudden the car drops into overdrive. the funny thing is, i could deactivate it by pressing the button on the shifter. but if i press it again to engage it, nothing happens. i did notice the temps were over 200 degrees. anyone close to virginia beach that can help me out?
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