Finding The Wires You Need - Viper 500+ Installation Manual

Optional Starter Kill Relay
If Starter Kill Relay or its connections are immediately visible upon removal of the underdash panel, they can easily
be bypassed. Always make the relay and its connections difficult to discern from the factory wiring! Exposed yellow
butt connectors do not look like factory parts, and will not fool anyone! For this reason, routing the starter kill wires
away from the steering column is recommended.
Now that you have decided where each component will be located, you're going to find the wires in the car that the
security system will be connected to.
IMPORTANT! Do not use a 12V test light to find these wires! All testing described in this manual is described
using a digital multimeter .
Obtaining Constant 12V
We recommend two possible sources for 12V constant: The (+) terminal of the battery, or the constant supply to the
ignition switch. Always install a fuse within 12 inches of this connection. If the fuse also will be powering other
circuits, such as door locks, a power window module, a Nite-Lite
IMPORTANT! Do not remove the fuse holder on the red wire. It ensures that the control module has its own
fuse, of the proper value, regardless of how many accessories are added to the main power feed.
Finding the 12V Switched Ignition Wire
The ignition wire is powered when the key is in the run or start position. This is because the ignition wire powers the
ignition system (spark plugs, coil) as well as the fuel delivery system (fuel pump, fuel injection computer). Accessory
wires, on the other hand, lose power when the key is in the start position to make more current available to the starter
motor.
© 1995,1997 Directed Electronics, Inc. Vista, CA
Step 2:

Finding the Wires You Need

How to find (+)12V ignition with your multimeter:
1. Set to DCV or DC voltage (12V or 20V is fine).
2. Attach the (-) probe of the meter to chassis ground.
3. Probe the wire you suspect of being the ignition wire. The steering column
harness or ignition switch harness is an excellent place to find this wire.
4. Turn the ignition key switch to the run position. If your meter reads (+)12V,
go to the next step. If it doesn't, probe another wire.
5. Now turn the key to the start position. The meter display should stay steady,
not dropping by more than a few tenths of a volt. If it drops close to or all
the way to zero, go back to step 3. If it stays steady at (+)12V, you have
found an ignition wire.
® headlight control system, etc.; fuse accordingly.
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97N437.597