The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post - 3 speed overdrive!!, now about getting it in.......

kieth · 06-15-2011, 01:49 PM

I did not look at the above relay wiring job, he wired it the way he wanted to, the instruction below are for a relay that comes prewired. Kieth

You will find the relay which is shown above with the plastic cap already prewired. I use them all the time.

1. The Blue wire is the supply for the 12 volt power to the relay.( Hot all the time)

2. The yellow wire is the supply of 12 volt power when you activate the relay

3. The Red center wire is not normally used but it supplies 12 volt power when the relay is not activated

4. The black wire is the ground for the relay (used here cleverly to only activate the OD when it is in the correct range of speed. )

5. The white wire is the trigger wire (activates the relay and sends power to the yellow)--controled here by a switch with a light that shows it is engaged)

They are really simple but when you look at them for the first time it gets really confusing ........Kieth

Only question I have is when you slow down does it automaticly downshift out of OD ?

here is a link to the prewired relay and how it is set up.

http://kieth.smugmug.com/Trucks/66-G...916151_PDBdGJX

06-15-2011, 01:49 PM	#42
kieth Registered User Join Date: Sep 2010 Location: Tulsa, Oklahoma Posts: 1,925	Re: 3 speed overdrive!!, now about getting it in....... I did not look at the above relay wiring job, he wired it the way he wanted to, the instruction below are for a relay that comes prewired. Kieth You will find the relay which is shown above with the plastic cap already prewired. I use them all the time. 1. The Blue wire is the supply for the 12 volt power to the relay.( Hot all the time) 2. The yellow wire is the supply of 12 volt power when you activate the relay 3. The Red center wire is not normally used but it supplies 12 volt power when the relay is not activated 4. The black wire is the ground for the relay (used here cleverly to only activate the OD when it is in the correct range of speed. ) 5. The white wire is the trigger wire (activates the relay and sends power to the yellow)--controled here by a switch with a light that shows it is engaged) They are really simple but when you look at them for the first time it gets really confusing ........Kieth Only question I have is when you slow down does it automaticly downshift out of OD ? here is a link to the prewired relay and how it is set up. http://kieth.smugmug.com/Trucks/66-G...916151_PDBdGJX Last edited by kieth; 06-15-2011 at 02:21 PM.