Odd '78 design features

[G B.]

Would a '78 owner out there please help me understand these unusual design features? I noticed them during a test drive. No offense meant; the features may just seem odd to me.

1) The interior courtesy lights stay on for about 40 seconds. Closing the door doesn't shut them off immediately. Starting the engine does turn them off. Are the lights on a timer that can be changed?

2) A buzzer sounds for about 10 seconds when I turn the car off and remove the key. This buzzer sounds with the headlights off and down, and even if I'm still wearing my seat belt. Opening the door does not turn it off immediately. What is this buzzer reminding me to do?

3) To turn the ignition key back to lock position, I have to depress a little lever behind the ignition switch with my other hand while turning the key. How does this lever make the car safer or perform better?

4) On the road the engine temperature peaks and remains at an indicated 205 degrees. This implies that GM had already gone to a 195 or higher thermostat in 1978. Is that the case?

[Joe L.]

Re: Odd '78 design features

Jerry-----

I don't own a 1978 Corvette and have never even driven one, but I may be able to offfer something with respect to some of your questions:

1) The courtesy lamp feature in which the light stays on for a certain period of time after the ignition is turned off, but goes off immediately when the door is opened is present on many GM cars. It's designed to give you some extra time with light to "get yourself together" before you exit the car. My 89 Cadillac Eldorado "driver" (my late father's old car) has this feature. Since, by 1978, Corvettes were becoming more-or-less a luxury car, I expect that this "luxury car" feature was added. There is no way that I know of to adjust or change the length of time the interior lights stay on;

2) I have no information on this one;

3) The steering column lever that you describe which must be depressed prior to turning the ignition switch to the "lock" position is also found on many other cars. I've noticed it on a lot of Ford products and some foreign cars. I believe that what's it's supposed to do is to prevent you from inadvertantly turning the ignition switch to "lock" at an "inopportune" time (like when you're driving), since the steering wheel locks in the "lock" position.

4) from 1966-onward all Chevrolet engines with the AIR emissions control system used a 195 degree thermostat. This higher engine operating temperature was supposed to improve the efficiency of this "afterburning" emissions control system. As I recall, all 1978 Corvettes used AIR, so all should have been equipped with 195 degree thermostats. Neither the thermostats, temp gauges, or sending units are "dead-on" precise, so I expect that a 205 degree gauge reading with a 195 degree thermostat is well within the cumulative error which could exist in the system.

[Joe L.]

Re: Odd '78 design features

Jerry-----

I don't own a 1978 Corvette and have never even driven one, but I may be able to offfer something with respect to some of your questions:

1) The courtesy lamp feature in which the light stays on for a certain period of time after the ignition is turned off, but goes off immediately when the door is opened is present on many GM cars. It's designed to give you some extra time with light to "get yourself together" before you exit the car. My 89 Cadillac Eldorado "driver" (my late father's old car) has this feature. Since, by 1978, Corvettes were becoming more-or-less a luxury car, I expect that this "luxury car" feature was added. There is no way that I know of to adjust or change the length of time the interior lights stay on;

2) I have no information on this one;

3) The steering column lever that you describe which must be depressed prior to turning the ignition switch to the "lock" position is also found on many other cars. I've noticed it on a lot of Ford products and some foreign cars. I believe that what's it's supposed to do is to prevent you from inadvertantly turning the ignition switch to "lock" at an "inopportune" time (like when you're driving), since the steering wheel locks in the "lock" position.

4) from 1966-onward all Chevrolet engines with the AIR emissions control system used a 195 degree thermostat. This higher engine operating temperature was supposed to improve the efficiency of this "afterburning" emissions control system. As I recall, all 1978 Corvettes used AIR, so all should have been equipped with 195 degree thermostats. Neither the thermostats, temp gauges, or sending units are "dead-on" precise, so I expect that a 205 degree gauge reading with a 195 degree thermostat is well within the cumulative error which could exist in the system.

[Greg A.]

Re: Odd '78 design features

Jerry,

I have a '78 Silver Anniversary. The timer feature is part of RPO ZX2 Courtesy Group. It includes the timer, convenience lights, and a spare timer lamp. The timer is an orange box about the size of a pack of cigarettes and in early '78 it was located on the left side of the dash near the light switch. Later in '78 it moved to behind the glove box.

I do not have the buzzer sounding as you describe. It must be a short of the the key warning or possibly the seat belt buzzer.

Joe is correct about the key release lever. My CA L-48 operates at a steady 205 degrees as yours does.

Greg.

[Greg A.]

Re: Odd '78 design features

Jerry,

I have a '78 Silver Anniversary. The timer feature is part of RPO ZX2 Courtesy Group. It includes the timer, convenience lights, and a spare timer lamp. The timer is an orange box about the size of a pack of cigarettes and in early '78 it was located on the left side of the dash near the light switch. Later in '78 it moved to behind the glove box.

I do not have the buzzer sounding as you describe. It must be a short of the the key warning or possibly the seat belt buzzer.

Joe is correct about the key release lever. My CA L-48 operates at a steady 205 degrees as yours does.

Greg.

[G B.]

Thanks for the help

Joe and Greg -

You've saved me some research time, and that's a real sweet gift these days.

I'll leave the courtesy light timer alone since it's working right.

I now understand the little key release lever. I think it's probably an impractical response to some weird lawsuit. As in: "when I turned the key to lock while going 80 on the freeway, the steering unexpectedly became stiff".

The indicated 205 degree engine operating temp must be normal for this model; it just seems a little high to me. A 180 degree thermostat will likely be installed in the future. Please don't report me to the EPA.

Greg, I'm going to check out the buzzer function some more. I think it may be linked to the seat belt warning since it seems to be on a timer. If it was a problem in the lights-on indicator or key warning, I think it would buzz forever.

[G B.]

Thanks for the help

Joe and Greg -

You've saved me some research time, and that's a real sweet gift these days.

I'll leave the courtesy light timer alone since it's working right.

I now understand the little key release lever. I think it's probably an impractical response to some weird lawsuit. As in: "when I turned the key to lock while going 80 on the freeway, the steering unexpectedly became stiff".

The indicated 205 degree engine operating temp must be normal for this model; it just seems a little high to me. A 180 degree thermostat will likely be installed in the future. Please don't report me to the EPA.

Greg, I'm going to check out the buzzer function some more. I think it may be linked to the seat belt warning since it seems to be on a timer. If it was a problem in the lights-on indicator or key warning, I think it would buzz forever.

[Greg A.]

Re: Thanks for the help

Jerry, I had the car out last night for the first time in several weeks. I was thinking the mid-position on the temp gauge was 210 and it always sits just a little below center. I realized last night that the mid-point is 200 degrees, so my temp runs a solid 195. Even in summer with the A/C on in city traffic, it rarely gets more than 205.

As Joe said, the error in the temp gauge is enough that it's hard to quibble about 10 degrees, but I consider myself lucky never having overheating problems...now if I could just do something about the heat in the passenger footwell, my wife would be happy!

Greg.

[Greg A.]

Re: Thanks for the help

Jerry, I had the car out last night for the first time in several weeks. I was thinking the mid-position on the temp gauge was 210 and it always sits just a little below center. I realized last night that the mid-point is 200 degrees, so my temp runs a solid 195. Even in summer with the A/C on in city traffic, it rarely gets more than 205.

As Joe said, the error in the temp gauge is enough that it's hard to quibble about 10 degrees, but I consider myself lucky never having overheating problems...now if I could just do something about the heat in the passenger footwell, my wife would be happy!

Greg.