1966 Corvette convertible rear compartment light

[Joe T.]

My rear compartment light does not come on with the front courtesy lights. I checked the bulb and it is good. No power to the socket. Not sure how the power gets from the door switch to the light.

[Donald A.]

Re: 1966 Corvette convertable rear compartment light

My rear compartment light does not come on with the front courtesy lights. I checked the bulb and it is good. No power to the socket. Not sure how the power gets from the door switch to the light.

Wiring diagram is in the service manual and free at the other forum via request but I would recommend the color laminated wiring diagrams from Dr. Rebuild they show connectors, wire colors, harnesses, everything! Would recommend you get a good wiring diagram and also a DVM (digital voltmeter) or any similar volt-ohm meter available for about 10-20 bucks. The courtesy light system is very simple - there is always a hot (+12V) source to the courtesy bulbs, and the door switches (or headlight switch if turned fully CCW) simply provides a ground source to the courtesy bulbs. So, first thing is look at the bulb and make sure it has the two contacts at the base like the ones in the footwell areas. Then take your 12v test battery and check the bulb make sure it lights via wires to the two connectors at the bottom of the bulb. Next take your DVM and check the light socket in the rear compartment. There are two wires to it. Hook one of your meter wires to a good known ground then use the other meter wire probe to check the contacts inside the bulb socket. There should be +12V on one of the wires. Now check the other wire that did not have +12V (door open and/or light switch full CCW). Use the "ohm" setting. You should get zero ohms on the other socket connector (indicating ground). If you don't there is a failure in that wire somewhere between the socket and the other end which goes through the rear wiring harness connector under the dash. Since your other courtesy lights work we know the system is otherwise intact. So you just have to find where the ground wire source has failed. If however there is no +12V on one of the rear courtesy light socket contacts then that wire has failed somewhere between the socket and up front, goes thru the rear wiring harness connector and ties in with the other courtesy light wires then goes to the fuse panel. You will have to trace it to find where it is broken or disconnected or whatever. Anyway, that is my approach, but the basics are you have to have the +12V and the ground to light the lamp and one of those is bad

[Joe T.]

Re: 1966 Corvette convertable rear compartment light

Thanks Don. I have a very good Fluke meter. I also have a service manual. A couple days ago I checked the bulb and it was good. I was not aware of checking both terminals in the socket. I only checked one for power with a ground to the socket. I will follow up on checking both terminals for power and/or good ground. The socket and wires seem to be fairly new but I will also clean the terminals. Did not know the ground wire went all the way to the switch.

[Richard M.]

Re: 1966 Corvette convertible rear compartment light

Joe, Don's got you covered. But to repeat, that socket is not grounded. It's attached to fiberglass so the ground is one of the wires. You said you checked voltage with your Fluke DVM with the meter ground at the socket. You won't get a reading that way as Don explained.

Also, as you may not be aware..... The 2 wires are terminated at the socket with bullet connectors. They plug into the back of the socket. Inside the socket are small springs and they get weak. Sometimes adding a bead of solder to each bulb contact helps.

Also, reproduction harnesses have been problematic with the size of the male bullet connectors for these sockets. If the harness is newly replaced it may be a loose connection on one or both of the bullets. I've had battles with those little buggers using new harnesses.

One other thing to check is where the 2 wires(orange(+) and white(gnd) traverse near the driver side decklid spring towers. It's possible a wire is cut from getting sliced by the tower hinge mechanism. The wires then go along the wheel well under the carpet, then down under the sill plate area under a wire cover plate beneath the carpet. Then behind the kickpanel and connects into the body connector at the main harness.

Rich

[Joe T.]

Re: 1966 Corvette convertible rear compartment light

Thanks for the info. I will check those points out tomorrow.

Joe

[Joe T.]

Re: 1966 Corvette convertible rear compartment light

Well, long story short. This is what I found. After checking the socket, no power and no ground. Went to the connector under the dash. Power and ground in and power and ground out. Followed the wires front to back. Attached is a photo. Also is a photo of my repair.

[Harry S.]

Re: 1966 Corvette convertible rear compartment light

Joe, congrats on finding the problem. Appears you avoided a fire.

As I recall GM wiring harnesses had a life expectancy of 15 years. I would consider replacing all of them if they appear very old, have cracks or feel brittle.

[Joe T.]

Re: 1966 Corvette convertible rear compartment light

Had a complete body off restoration 4 years ago. It sat without being run for 3 years. Not sure what happened to the wires in that spot. Could have been defective or damaged during reassembly. Glad I found the problem. It could have been much worse, as you said. Even the way it was I had all rear lights and controls except for the compartment light.

[Jimmy P.]

Re: 1966 Corvette convertible rear compartment light

Hi Joe,
Nice to see you figured things out. Lucky that you did too by the looks of those wires.
Welcome to the NCRS and to TDB. You'll gets lots of expert help here for your 66.
By the way did you get the PTSC application?

[Joe T.]

Re: 1966 Corvette convertible rear compartment light

Thank you. I did receive it. Thanks for your help in joining the NCRS.

[Richard M.]

Re: 1966 Corvette convertible rear compartment light

Looking at that removed section of the harness....

What's really strange is it appears the PINK wire is bare. Somewhere in that melted bundle is the ORANGE, which is the Power to the compartment lamp. Both PINK(fused power to the Fuel Sender via IGN = ON), and ORANGE(also fused, constant power), somehow survived the meltdown without blowing either fuses. Something caused the meltdown.

Was the rear harness underneath the wire cover below the carpet? Did it appear to be rubbing the bare metal of the cover? Was the rear harness replaced during the restoration?

Just out of curiosity, try to separate those melted wires. I'd suspect the ORANGE or the WHITE wire is open circuit. If the PINK melted and was shorted to WHITE(GND), it may have opened the WHITE wire and possibly melted elsewhere too. My concern would be the integrity of the rest of the harness where it traverses back to the rear lamps, etc.

Your localized repair looks good, but as suggested, I would be inclined to replace that entire rear harness.

Rich

[Leif A.]

Re: 1966 Corvette convertible rear compartment light

Joe,
Welcome to the TDB. As others have wisely recommended, replace the rear wiring harness. Where that particular harness runs you're not only dealing with flammable fiberglass but the gas tank. CHEAP insurance to replace.

https://www.lectriclimited.com/rear-body-harness-103771

P.S. Peace of mind is priceless!!

[Harry S.]

Re: 1966 Corvette convertible rear compartment light

Also look at M&H http://www.wiringharness.com/

[Joe R.]

Re: 1966 Corvette convertible rear compartment light

Yes, if you are going to replace the wiring harness M & H would be my recommendation.

JR

[Joe T.]

Re: 1966 Corvette convertible rear compartment light

Checked the harness all the way back. New rear lighting, sockets and wiring. No other defects in the harness. Can't understand how everything worked except the rear compartment light prior to repair. Also, why no fuses were blown. The two harnesses to the rear ran under the carpet. No burns on the carpet. No metal cover on the harness. Everything is working fine now. The rear compartment light is working fine. Don't think a new harness would resolve any problems since everything seems to be good. I will check the fuse amps to make sure higher amp fuses were not installed. I am an x engineer and this one has me baffled. I purchased the car after the restoration. I am in the learning mode on this 66 Corvette wiring, although having a good understanding of voltage, grounds, shorts and so on. Thoughts are well appreciated.