Home page

Topic: Doug Nash 4+3

in Forum: C4 Electrical


Already a Member? Click Here to Login
Not yet a Member? Click Here to Register for Free!
Doug Nash 4+3 (1/2)
 8/29/21 1:52am
dgcarbu
Standard Member
Send Private Message

Sacramento, CA - USA

Vette(s):
1985 Corvette 5.7 TPI


Joined: 8/28/2021
Posts: 1

Had my 85 C4 Doug Nash 4+3 transmission rebuilt, but there remains an issue with the overdrive switch that isn't supplying 12v to the solenoid that enable the +3 overdrive, and apparently affects reverse according to the Transmission shop...

 

Does anyone have suggestions or a detailed schematic for this?

Our Sponsors help support C4VR
Re: Doug Nash 4+3 (2/2)
 8/30/21 7:19am
Adams' Apple
Standard Member
Moderator
Send Private Message

Duncanville, TX - USA

Vette(s):
1985 Coupe-L98/Auto,Bright Red/Carmine. 1974 Coupe-L48/4speed, Medium Red Metallic/Black Deluxe.


Joined: 3/18/2009
Posts: 2173

The O/D section of the Nash unit has nothing to do with reverse not working. The O/D clutches either hold, or they do not. A problem in reverse would also translate to a problem in the forward gears. I can't remember off the top of my head if the O/D solenoid is GROUNDED by the switch, or if the switch provides power to the solenoid. MOST GM systems have 12v power to the solenoids any time the key is on, and the ECM or switch provides a ground. I can look at the diagrams and post how it works later. What kind of issue are you having with reverse?

A quick glance at the diagrams shows the O/D switch only provides a ground signal to the ECM. From there, the ECM sends out a signal to the O/D relay, which then sends a signal to the O/D solenoid in the trans.




|UPDATED|8/30/2021 4:19:26 AM (AZT)|/UPDATED|


______________
Joel Adams  
My Link

 
   
(click for Texas-sized view!)             NCRS

"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
Our Sponsors help support C4VR