Dome Light
Safety Car
Joined: Oct 2007
Posts: 4,360
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From: Seattle Area Washington
If you have the Convenience Group Package option there is a interior delay timer. It is located between the speedometer & tachometer taped to the main dash harness. The delay timer if faulty can keep the interior lamps from turning off.
Race Director
Joined: Oct 2000
Posts: 12,642
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From: Shamong, NJ
There's a pretty good chance your 77 has RPO ZX2 Convenience Group since close to 41000 of the 49000 77's built were ordered with it. Besides the dome and courtesy lamps delay feature, ZX2 also included a visor mirror, headlights on buzzer, low fuel warning light and an engine compartment lamp. 77 was the first year the courtesy lamp delay was offered.As bmotojoe say, the timer should be taped above the column, a less than easy place to get to. I think 77's used the same timer as 78-82's, which had the part number, 4635989 molded into the case, were about 2" square and were orange plastic, though I've seen a couple gray plastic ones over the years too. The timers are no longer available but most Corvette vendors carry a repair kit that includes a new circuit board for the timer.
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Safety Car
Joined: Oct 2007
Posts: 4,360
Likes: 1,724
From: Seattle Area Washington
There's a pretty good chance your 77 has RPO ZX2 Convenience Group since close to 41000 of the 49000 77's built were ordered with it. Besides the dome and courtesy lamps delay feature, ZX2 also included a visor mirror, headlights on buzzer, low fuel warning light and an engine compartment lamp. 77 was the first year the courtesy lamp delay was offered.As bmotojoe say, the timer should be taped above the column, a less than easy place to get to. I think 77's used the same timer as 78-82's, which had the part number, 4635989 molded into the case, were about 2" square and were orange plastic, though I've seen a couple gray plastic ones over the years too. The timers are no longer available but most Corvette vendors carry a repair kit that includes a new circuit board for the timer.
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This timer GM #461294 was used on the 77 & early 78...
Ebay Link:https://www.ebay.com/itm/37474674969...SABEgJqefD_BwE
Once you locate the timer it is easy to bypass...
The connectors on the drawing I marked with a black arrow C121 C=connector
At the timer harness you will see a pair of connectors, one with a single white wire with black tracer...And a connector with a pair of solid white wire...
Disconnect those 2 connectors from the timer and plug the 2 connectors from the main harness into each other as shown in the photo right of Courtesy Electrical diagram...
Race Director
Joined: Oct 2000
Posts: 12,642
Likes: 3,103
From: Shamong, NJ
To the OP, if your car does have the underhood light than you do have the Convenience Group, and it's quite likely your problem is with the delay timer as described by bmotojoe above.