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barrys
Member
- Joined
- Nov 13, 2008
- Messages
- 280
- Reaction score
- 1
- Points
- 16
- Location
- Bay Area, CA
- Vehicle Year
- 2010
- Make / Model
- Ford
- Engine Size
- 4.0 V6
- Transmission
- Automatic
But seriously folks... I noticed my fog lights were on after I got out of my truck. Headlights were not on, keys in pocket. Etc...
I read up on how they work. I was able to get them to come on once when wiggling the switch with the ignition on and the lights off. They do come on when they are supposed to according to the owner's manual.
I pulled the fog light relay (48B in engine box). The relay bench tested as normal with 12V, up to 2A control voltage. In banging the relay upside down on the table with no trigger voltage got teeny beeps out of the continuity meter but that would be the truck bouncing on it's roof, not parked. (Grr) I ordered a replacement relay but I don't expect that to fix anything.
The more I read logic charts on the fog light switching the more I go back to my time in grad school for computer engineering (which is sad). Bad light switch, combo switch, high and low beam circuits involved, and something about negative or ground switching logic which explains why disconnecting the light switch did not make the fog go off. I read some great posts on the logic and wiring from pjtoledo and Earl43P - thank you, saved everything. I used the fog lights once when I got the truck to see if they worked and never since. But, I like having everything working.
I would just like to hear ideas on what and how to do more testing, thoughts about the described behavior, snippets from special workshop docs, and/or hacks around all that logic with the right safety since I read too many posts about stuff melting. I looked up all the fuse and relay locations. And, of course, it was raining today, so dry test results coming up... I'll skip the highlighting and emoticons since I want to hear from people who got all the way through this wall 'o text.
I read up on how they work. I was able to get them to come on once when wiggling the switch with the ignition on and the lights off. They do come on when they are supposed to according to the owner's manual.
I pulled the fog light relay (48B in engine box). The relay bench tested as normal with 12V, up to 2A control voltage. In banging the relay upside down on the table with no trigger voltage got teeny beeps out of the continuity meter but that would be the truck bouncing on it's roof, not parked. (Grr) I ordered a replacement relay but I don't expect that to fix anything.
The more I read logic charts on the fog light switching the more I go back to my time in grad school for computer engineering (which is sad). Bad light switch, combo switch, high and low beam circuits involved, and something about negative or ground switching logic which explains why disconnecting the light switch did not make the fog go off. I read some great posts on the logic and wiring from pjtoledo and Earl43P - thank you, saved everything. I used the fog lights once when I got the truck to see if they worked and never since. But, I like having everything working.
I would just like to hear ideas on what and how to do more testing, thoughts about the described behavior, snippets from special workshop docs, and/or hacks around all that logic with the right safety since I read too many posts about stuff melting. I looked up all the fuse and relay locations. And, of course, it was raining today, so dry test results coming up... I'll skip the highlighting and emoticons since I want to hear from people who got all the way through this wall 'o text.
