Your main ignition wiring looks good. You should split the Vipers +12V input load between the vehicles Red and
RED / White +12V constant wires instead of just using the only Red wire. Additionally, H1/1 should be connected
to +12V constant.
The DB-ALL2 should be flashed with 402.GM5 Ver 3.11 firmware for the 2003 Venture. Did the DB-ALL2 programming
procedure follow the Type 1 programming steps exactly?
You didn't mention if you are going W2W of D2D between the Viper and the DB-ALL2. Either way, there are a couple
of mandatory hardwire connections. The Vipers thick Pink IGN1 wire goes to both the van and the DB-ALL2. Same
for the thick Yellow Starter wire. This is shown on the Type 1 install diagram.
The Vipers Neutral Safety Switch must be plugged in and set to ON. In D2D Mode, the van's Parking Brake must be ON
to remote start ( or connect H2/2 to Chassis Ground ).
The Viper must be programmed to Transmission Mode = Automatic, Menu 3, Item 1, Option 2.
If I remember correctly, the Venture had "one-touch" starting. If that is correct, you can run the Viper with Engine Checking
= Fixed and let the van handle the cranking ( like it normally does ). That also means the Tach signal and Tach Learn is
not necessary. See Menu 3, Item 2, Option 3.
While not part of your current problem, there is a Brown ACC2 wire. It may not be necessary to power this wire during
remote start ( I always do just to duplicate everything the key start does ). If you decide to power this wire, here is the
wiring ( you will need a 30/40 Amp SPDT Relay and in-line fuse holder w/20 Amp fuse ):
Relay Pin 85 to Viper H2/22 thin Orange (-) 200mA Accessory Output
Relay Pin 30 to van Brown ACC2 wire
Relay Pin 86 and 87 to +12V through 20 Amp fuse
The clicking you hear with a remote start attempt could be the Parking Light relay giving an Error Code. Have you tried
running Shutdown Diagnostics ( if the Parking Lights are connected / working you could count the flashes ) ?
Soldering is fun!