Several months ago I replaced the radiator, thermostat and hoses on my car(L98, automatic). Since I have replaced these items, the horn does not work(except for the anti theft system), and the low coolant light keeps flickering on and off. The fluid level is fine and the car runs normal tempurature. Any ideas? I believe I will repalce the coolant sensor, but I don't know why the horn no longer works. Any help would be appreciated. Thanks.

The horn is on the same side as the coolant recovery tank(at least on my '85 it is). Perhaps you moved/disconnected the wires at the horn? Can you hear the horn relay click when you press the horn button?
Can you shoot 12v directly to the horn(s) and get them to toot?
The low coolant light can come on if the coolant system is not filled and bled properly, since the rad. neck is higher than the thermostat housing...

know this is a while after the post but a friend had an 88 and had problems with the light. what it turned out to be was the hose to the overflow tank had a split on the bottom that he could not see. repaired the hose and problem went away. just something to check.

check your ground for the horn i do belive its on the left side of your rad..........vettes are notorius for bad grounds.........