Directed Electronics MERLIN 2000 - Manual (Page 6)

6 © 2001 Directed Electronics, Inc. Vista, CA
finding the wires you need
Now that you have decided where each component will be located, you’re going to find the wires in the vehicle
that the security system will be connected to.
IMPORTANT! Do not use a 12V test light to find these wires! Use a digital multimeter for all testing.
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, fuse accordingly.
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.
The ignition wire is powered when the key is in the run and start positions. This is because the ignition wire
powers the ignition system (spark plugs, coil) as well as the fuel delivery system (fuel pump, fuel injection com-
puter). Accessory wires lose power when the key is in the start position to make more current available to the starter
motor.
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 battery ground.
3. Probe the wire you suspect of being the ignition wire. The ignition switch harness is an excellent place to
find this wire.
finding the 12V switched ignition wire
obtaining constant 12V