Whoa, no tail lights!!

[medwards01]

Driving the EB home from work Thursday night, I got honked at by several vehicles in the passing lane. Well heck, I thought they were just admiring the Bronco. Imagine my surprise when I pull in the parking lot at Harris Teeter and the cart jockey yells out that I don't have any tail lights!! Just my luck, it's going to be colder than a "well diggers arse" again this weekend in Wilmington with the possibility of snow and sleet, and now I've got to troubleshoot this problem....I did a search here on the Early Bronco Tech forum for info and learned from other posts that there could be several causes. Anything from headlight switches, dimmer switches, and ignition switches, to fuses, faulty wiring, and poor grounds....I noticed over the last week when I depressed the dimmer switch the headlights would go out on occasion. I could depress the switch again and the headlights would come back on. This leads me to think that the dimmer switch may be the culprit causing no tail lights. What do you guys think? Any troubleshooting tips prioritized from the most likely to the least will be appreciated....I absolutely hate troubleshooting in cold weather!!

cratchhe: :banghead: cratchhe: :banghead:

[JayT]

In my experience, bronco or other, grounding has been my #1 problem. Keep in mind, I'm more a FSB guy, so my help on an EB is just barely more than shooting blind... but grab yourself a meter (saving my "Good meter" speech for later) and start at the taillights. Work toward the dash and see where you lose the power. Your symptoms sound like it could be the dimmer switch, so I suppose you could check that out first by either temporarily bypassing it, or ohm it out with your meter.

[blazinchuck]

well after driving home tonight with headlights going on and off...(me frantically hitting the headlight switch knob) i think the dimmer can cause a lot of problems, but so can the switch...cause tapping the switch turns them off and on. I will be replacing both, the switch and dimmer tho. have you ever noticed the head lights going out?? cause if they arent going out...then it might be in the harness to the tail lights

[chuzie]

Switch would be my first stop. Pull it and run a hot 12v to the tail light wire and see if they work then you know it is the switch. Since you have power to the other lights we can rule out 12v power to the switch.

[broncosbybart]

The dimmer should have nothing to do with the tail lights. Me thinks bad grounds are very likely. You can use a test light to check for voltage and they are a lot easier to use than a multi meter, IMHO. The good thing is that there are not very many wires to be concerned with on these old beasts. I would start by cleaning a small area on the rear of the frame to use as a ground for your test light and checking the sockets for 12V with the lenses off and bulbs out. The tail lights do not have a ground wire, The metal housing is grounded to the body by the 2 large phillips mounting bolts. If you do not get 12 V to the sockets, you know to check elsewhere for power supply issues (bad connections, faulty switch, or wiring issues). If you do get power to the socket with your headlights or brakelights on you know that it is a grounding issue and things just need to be cleaned up. I hope you find the problem quickly. Not a fan of the cold either...