Re: 2001 grand Marquis does not start after rain
I found this online but ain't too sure it'll help or not. I'm guessing if you were able to bring the car to the dealer and pressure wash it really good, you can duplicate the problem and then they'll be able to properly diagnose it; unless it pours rain when you get there! Hopefully you won't have to do a trade in:
l U1262: This code indicates a communication issue (Bus+, Bus-) between the PATS/HEC/ICM and some other module. Do not perform PATS diagnostics if a no start is not reported of if theft indicator is not flashing rapidly at ignition RUN position. If the indicator is flashing, check to make sure the PCM is powered up and operating. If it's not, continue with PCM diagnostics.
'11 Ram Quad Cab 4x4 SXT 5.7L HEMI (stock); 48,500m
'06 Pontiac G6 GT 3.5L 220hp; 64,000m
'12 Chrysler 200 Limited 3.6L 283hp; 28,000m
'99 Taurus 3.0L 2V Vulcan 145hp; 154,300m - Traded
Amsoil in all vehicles!