Often during wet inclement weather, the ambient light level is too high
for the autolamp system to automatically engage the headlamps, but it is
desireable for the lights to be illumunated to increase visibility to other
motorists. On 2001 and later crown victorias, the headlamps and parking lamps
automatically illuminate when the windshield wipers are turned on. But on
earlier vehicles, the autolamp system is not interfaced with the windshield
As explained on the autolamp retrofit page, when +12V is present on autolamp
enable input of the lcm, the headlamps will turn on around 20 seconds later.
And after the input is removed, the headlamps will shut off around 20 seconds
The first part of the project is finding a switched voltage source that
only provides +12V when the windshield wipers are engaged. The wiper switch
on the steering column uses a resistor multiplex bus so it will not be a
suitable voltage source without designing extra circuitry.
But the windshield wiper motor has two limit switches built into it to
control the intermittent delay feature and allow the wipers to properly park
themselves. When the wipers are parked, both of the limit switches rest
at ground. When moving, one will be at +12V until the end of the travel range
at which point it will pulse to ground and the other one will momentarily
pulse to +12V.
If the limit switches were connected directly to the ambient sensor, the
ambient light sensor output would be shorted to ground when the wipers were
parked. This would damage either the demand lighting output of the LCM or
the sensor if the fuse did not blow first. This would also create crosstalk
between the two limit switches so that the wipers would not park properly.
But using a pair of diodes to interface the limit switches to the lcm
will alleviate the problems mentioned above and provide a +12V source whenever
either limit switch has +12V present on it. With the revision of the lcm
software in my 98' police interceptor, connecting only the black/pink wiper
park switch to the lcm autolamp enable input was sufficent to trigger the
lamps when the wipers were on. But to be on the safe side, I diode connected
the other limit switch to the LCM anyways to remove the periodic 0V pulses.
The wiper control module is a black box held on with a single bolt above
the ashtray and below the climate controls. Accessing the module is easiest
if you remove the ashtray first. The wires that we're after are ([Pin 6]
- Black/Pink) and ([Pin 13] - Red).
At the LCM located above the gas pedal, we're after the bottom connector
Pin 7 with the White/Pink wire.
In 01' ford added wiper activated headlamps to the crown vic, by connecting
one of the limit switches to a new input pin to the c2027 lcm connector.
When Pin15 on c2027 recieves a +12V input for several seconds, it turns on
the headlamps and then waits several seconds before turning them off after
the signal is removed. So if the vehicle operator momentarily uses the winshield
wipers for a quick washer spray and wipe, the lights will not engage. One
common complaint about the wiper activated headlights on 01' & 02' vehicle's
is that there is no way to turn off the headlights without also turning off
the wipers. If black/pink input wire to the lcm from the wiper control module
were cut, this would disable the wiper activate headlights all together.
If the modification mentioned above for 95'-00' vehicles were now done to
the 01' or 02' vehicle, the wiper activate headlight feature would only be
active when the headlamp knob was in the autolamp position.
In conclusion, the wiper activated headlamp retrofit project works well
in my vehicle. And it also helps me avoid leaving the headlamps on when
I shut off the vehicle. I have grown so accustomed to the delayed exit feature
leaving the lights on, that I often don't remember to shut off the lights
after I manually turn the on by the headlamp switch until after the [engine
off/lights on/door ajar] warning chime sounds.
Questions or Comments?
Email Me: [email protected]