duzak

hey all, new to this forum. i have a question regarding the 4+3. There is 4 green wires in the harness by the trans and i hear the transmission has to be at 140 degrees to send the signal to the overdrive. whats the voltage on green wire i should read going to overdrive? also is that servo on the left side of the trans.

glava2876

Not sure about the wires, but I have an 84, that had the transmission replaced with an 85 and they have to reach 185 degrees to engage the overdrive.

FOURSPEEDVETTE

I think it has to be 160 Degrees for O/D.

coupeguy2001

closed loop only, what ever temp that is for your car. Usually, it's about 123 degrees or so.

The early 4+3 had gear switches to alert the ECM what gear it was in.
Later ones just had the first gear inhibit switch and the wire at the back of the trans is for the engage solenoid and is indeed 12 volts.

rodj

84 176F
85 140F
86-88 122F

"There were also changes in the amount of side cover switches on the 4 speed section.
All 1984 cars had 3 switches (1st, 2nd, and 4th ).
1985 , 1987, and 1988 cars had a 1st gear switch and 1986 cars had none".

duzak

Thankyou for responses, i know there is a side switch and then one of them must be for reverse? My oil temp gauge is always at low it doesnt even read a number, im wondering if this may be the cause of the problem?

vetteoz

ECM which controls O/d works from engine coolant temp ; not oil temp
Reverse switch is on trans casing , not the side cover
Single 1st gear switch shown on side cover