Electric issues

FATHOMFOREVER

MEMBER
1997 CHEVROLET SILVERADO
5.7L
V8
2WD
AUTOMATIC
197,000 MILES

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.

Saturday, April 28th, 2018 AT 7:23 PM

3 Replies

STEVE W.

MECHANIC
15,434 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.

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Sunday, April 29th, 2018 AT 9:02 PM

FATHOMFOREVER

MEMBER
1 POST

Thank you so much. Will try your suggestions. It is definitely been a brain wrecker.

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Monday, April 30th, 2018 AT 10:48 AM

STEVE W.

MECHANIC
15,434 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.

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Monday, April 30th, 2018 AT 3:22 PM