Electric issues

1997 CHEVROLET SILVERADO
197,000 MILES • 5.7L • V8 • 2WD • AUTOMATIC
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FATHOMFOREVER
  • MEMBER
  • 1 POST
Truck will not start with key. Had to put in a push button start. Brake lights stay on until I push the brake then they go off. Air conditioner stopped working. All the panel lights are not working. Already changed out ignition switch and harness. Checked everything I could think of as far as ground wires and relays.
As soon as you turn the key and everything turns on brake lights will not work. When truck is running and hit the brakes they will not turn on and the hazards will not work either.
All this happened after we had a really bad thunderstorm.
Apr 28, 2018 at 12:23 PM
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STEVE W.
  • ✓Experienced Mechanic
  • 15,381 POSTS
Well my guess would be that you had a lightning strike somewhere nearby and a high voltage EMP may have went through your truck and damaged the Body Control Module. One thing you could try would be to disconnect the battery for ten to fifteen minutes and see if anything changes when it is reconnected. The other thing would be to connect up a factory level scan tool and query the system and see which modules are operational and talking on the data lines.
Apr 29, 2018 at 2:02 PM
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FATHOMFOREVER
  • MEMBER
  • 1 POST
Thank you so much. Will try your suggestions. It is definitely been a brain wrecker.
Apr 30, 2018 at 3:48 AM
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STEVE W.
  • ✓Experienced Mechanic
  • 15,381 POSTS
I have seen similar things in modern farm equipment as well when there is a close strike. Things will stop working or start acting strange. With all of the computers and wiring in modern cars it just makes them more vulnerable.
The other possibility is that water managed to get into the BCM, which would give the same end result.
Apr 30, 2018 at 8:22 AM
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