Have you discussed this with your friend? Maybe you should have tried him first.
Do your hazards work? The turn signal circuit goes through the hazard switch, maybe he forgot to plug it back in.
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-2000 Toyota 4Runner Limited 4WD Supercharged (silver/black, heavily modded, Team JBL)
-1991 Chevrolet Corvette ZR-1 (red/gray, stock)
-2004 Sentra SER (yellow, stock)