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Join Date: Dec 2009
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This may not be much help, but when I'm doing electrical diagnostics, I try to break the circuit into pieces to try to isolate a segment at fault. I would start at the brake switch. I would check for 12 volts on one leg. If you don't have power to the switch, then I'd go looking for why. If you do, then I'd jumper the connector and see if the brake lights came on. If they do, then the switch (or it's adjustment) is at fault. If they don't, then the problem is between the connector and the switch. Let's say they didn't come on. Then, I'd find the connector near the rear bumper that the frame wire connects to where it splits to the two sides. Check for power there when the brake switch is applied. Yes - problem is further downstream. No - problem is between the switch and that connector. By halving your area of interest each test, you'll eventually get it narrowed down to a specific spot.
2003 F-250 XLT Crew Cab 7.3L, Chrome BigTex Grille Guard, Quad pillar - 3 ISSPRO gauges (trans, pyro, boost) and DP-Tuner F6; Roush fuel pressure / temperature / oil pressure gauges, Ford Severe Duty AIS, 31 row 6.0 transmission cooler, ScanGauge II, Marinco mod, Walker BTM
I wonder if clouds ever look down on us and say, "Hey, look - that one is shaped like an idiot!"