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
(fuel pump, fuel injection computer). Accessory wires lose power when the key is in the
start position to make current available to the starter motor.
How to find (+) 12v ignition with your multi-meter:
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 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.
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Summary of Contents for HA-240 Lite v3
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