Steve0625
Member
When tapping into or adding STT lights to many newer vehicles the "lamp out" fast flash or warnings occur. The way around this is to use the trailer light tie ins. This solution should work for any vehicle that has the trailer tow wiring in place. Ford seems to include it in all of their light trucks, and Chevy/GMC may, as well. Dodge too for that matter.
S/T/T/R in the trailer tow wiring are all controlled by fused relays that are turned on and off by the CANBUS or PCM. Essentially, they don't care about too little or too much current draw in the way that the computers do for the normal S/T/T/R. The PCM or CANBUS senses the difference from what is expected and signals a fault of some kind, especially the dreaded fast flash/bulb out when it sees an LED in place of the expected incandescent. The trailer tow wiring works the way that everything used to do.
Taken from http://elightbars.org/forums/f13/fast-blinker-but-bulbs-still-there-49677/#post388138
S/T/T/R in the trailer tow wiring are all controlled by fused relays that are turned on and off by the CANBUS or PCM. Essentially, they don't care about too little or too much current draw in the way that the computers do for the normal S/T/T/R. The PCM or CANBUS senses the difference from what is expected and signals a fault of some kind, especially the dreaded fast flash/bulb out when it sees an LED in place of the expected incandescent. The trailer tow wiring works the way that everything used to do.
Taken from http://elightbars.org/forums/f13/fast-blinker-but-bulbs-still-there-49677/#post388138