C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

C4 1991 Alarm Question

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Old Jun 14, 2025 | 11:40 AM
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Default C4 1991 Alarm Question

Hi guys, I replaced the battery today on my C4 (1991 L98) and now I have an issue wit the alarm. As soon as I connect the battery, the alarm goes off and the horn honks. I tried locking and unlocking both doors but it still honks. I can start the car, but the honking doesn't stop. Only way to stop it is disconnecting the battery. Any ideas?

Thanks

Markus
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Old Jun 14, 2025 | 12:24 PM
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Did you do the lock unlocked at the key or door switch
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Old Jun 14, 2025 | 12:58 PM
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I don't have a keyfob so I simply put the key in the doors. I noticed that the passenger side was a bit hard to turn, so I sprayed some WD40 everywhere, maybe that helps. Will try again later
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Old Jun 14, 2025 | 02:52 PM
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I always found that a open with key and a start pretty much cleared alarm problems, besides if the car starts I would say problem has cleared.
Off hand is there a second none GM with a hidden switch like on my blazer
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Old Jun 14, 2025 | 03:13 PM
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That's my thought as well, if its only factory then the car would honk and not start. Probably the PO played around with it...
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Old Jun 14, 2025 | 03:49 PM
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Originally Posted by MarcusFromSwitzerlan
That's my thought as well, if its only factory then the car would honk and not start. Probably the PO played around with it...
Do you have the FSM(Factory/Field Service Manual) so that you can properly read, understand and then accomplish appropriate diagnostics for your car?
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Old Jun 15, 2025 | 09:31 AM
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OK, so it was apparently the passenger door. After a good spray with WD40 into the lock and opening / closing the door with the key a couple of times the "Security" light went from solid to blinking and the alarm didn't start again,
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