Towing Relays | Flasher Monitors | Details
The most common type of device fitted to cars when they are wired for towing is a flasher monitor. The function of a flasher monitor is to meet the legal requirement to provide a warning, visible or audible, that the indicator lights of a drawn trailer are working or not working.
Some flasher monitors incorporate switching relays and some simply monitor the working of the trailer indicators. The most obvious difference between types is between boot-fitting and front fitting. These types are described in full on the pages that follow.
Boot-fitting monitors
By far the most common is the simple boot-fitted audible monitor. The other common type is the Flasher bulb-failure bypass relay described in the section on Bypass Relays.
Front-fitting monitors
Front monitors are likely to be fitted under the dashboards of vehicles, monitoring current as it enters or leaves the vehicle's flasher control circuits. These circuits are usually incorporated in a self-contained flasher relay but many vehicles have the flash rate controlled by circuitry in a larger control board, with simple switching relays working as slaves" to switch the current.
Most monitors that check the current in or out of the flasher control circuits are installed by cutting the appropriate wire to or from the relay or to the flasher switch and wiring the monitor in line. As cars increasingly use printed circuit boards to carry current where previously wire harnesses were used, finding an appropriate wire to cut has become increasingly difficult. Plug-in monitors make it easy when flasher relays are readily accessible.
The "Midwife" 3 to 4 pin flasher adaptor and the more universal "Clone" adapter make it easy to attach a monitoring device to the original flasher relay and just plug back in.
See Flasher Monitors for full range of relays and fitting details.