come across tow trucks on which the turn signal lights blink too
fast. It's the most common complaint with turn signals, short of
outright failure to work. The problem afflicts both old and
brand-new trucks. Here are three ways to solve the problem of turn
signals that blink too rapidly:
1. Install a heavy-duty
Many truck chassis come new with a thermal flasher of the sort you see on
passenger cars. If the turn signal lights flash too rapidly and
weakly, remove the thermal flasher and install a heavy-duty electronic
flasher, available at auto parts stores. Thermal flashers can be
identified by their metallic body, which can't be seen through.
Electronic flashers have a plastic body, which is sometimes transparent
enough for you to see the electronic devices inside. Electronic
flashers are better able to handle the extra load of the multiple turn
signal lamps on tow trucks.
2. Use incandescent
lamps instead of LEDs.
LED lamps, which have become popular for their distinctive look, use much
less current to operate than regular incandescent lamps. While
reduced current draw is a good thing in most situations, it interferes
with the operation of the flasher when you use LED lights as brake and
turn signal lights. Replace LEDs with incandescents and see if turn
signal performance improves. On tow truck beds with four red LED
sealed lamps at the rear of the bed, for example, replacing even just one
LED lamp on each side with an incandescent lamp will often add enough load
for the flasher to work properly.
3. Wire into main
chassis harness, not into trailer harness.
One way the truck equipment industry has changed since I started in it
back in the 1990s is that new chassis manufacturers are becoming more
upfitter-friendly. Chassis now come with trailer wiring and switch
panels made new at the factory by the chassis manufacturer, to which the
upfitter can connect loads. For instance, a 1997 Ford 1 1/2-ton
chassis had only one left turn and brake light wire where you could
connect your wrecker bed lights, whereas a 2007 Ford 1 1/2-ton chassis has
a chassis left turn and brake wire and a trailer left turn and brake wire,
both original equipment from the Ford factory, both lighting up when you
move the turn signal lever. This proliferation of complexity and
upfitter options provides more opportunities for the build job to go
wrong. If you wire your wrecker bed into a factory harness turn and
brake light wire and the turn signals blink too fast, see if there's
another, unused wire in the factory wiring harness that also lights up
when you move the turn signal lever. Turn signal performance
sometimes improves if you run your wrecker bed turn signal lights off the
factory chassis harness, instead of off the factory trailer harness.