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Here I will outline building your own fuse block and attach relay sockets. This is a general guide that will work for most any wiring harness. I use this same basic setup for LT1, LS1, Vortec Trucks etc.
First off, the parts you will need to build the fuse block and OBD2 Diagnostic Port.
I have found that AUTOZONE can order you the fuse block, with terminals for $5.00 part# is 85668. This is a Dorman part. From www.rockauto.com its less then $3.00.
FUSE BLOCK WIRING
The relay sockets from allelectronics will have short wires in them, with terminals. DO NOT use these, you can insert a small screw driver in the slot on the top and bend the tab, and remove them. Order new terminals. The stock wires on these relay sockets are not up to the current needs of the fuse block. Also, these sockets are the only ones I can find, that will slide onto the side of the fuse block.
Order extra terminals incase you need to re-do something, for OBD2 port, Relay sockets, Fuse holder, etc, they are not expensive, $0.10 to $0.25 each or so. I always crimp AND solider all my connections.
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OBD2 DIAGNOSTIC PORT WIRING
All OBD2 port's for LS1, Vortec Truck are the same.
Pin 2. - Serial Data - FROM the PCM.
Pin 4 & 5 - GROUND - Usually only pin 5 is needed, however some scan tools/code readers will need GROUND on pin 4 as well.
Pin 16 - 12v+ BATTERY - Power from 12v+ Battery source.
OBD2 LT1, 96-97 ONLY will have additional wiring to OBD2 port.
Pin 6 - Diagnostic Request/Field Output Enable
Pin 9 - UART Serial Data
1995 LT1 used an OBD2 port, but were not OBD2 vehicles. These did not have a Serial Data on Pin 2. These used pin 9.