3-wire harness for vehicles without ECM. One wire for Ground, one for Ignition, and the other for a power source.
Geotab Document: https://www.geotab.com/documentation/hrn-cw03k3/
There are three connection wires when using the HRN-CW03S3 harness:
Black Wire
- The "Ground" wire, which should be connected to a known good chassis ground. Yellow Wire The constant power supply wire (12V or 24V) which should be connected to a genuine battery source (under voltage at all times). The fuse size is 5A.
Yellow Wire
- The ignition detection wire, which should be connected to a genuine ignition source (under voltage when the key is in the ON position and running, without voltage when the key is off). The fuse size is 5A.
Red Wire
- The constant power supply wire (12V or 24V) which should be connected to a genuine battery source (under voltage at all times). The fuse size is 5A.
✱ NOTE: The red and yellow wires must be connected to a source with a fuse, or the user must install the fuses.