Can someone tell me with 72 corvette my interior lights fuse has no power both sides ,( all other fuses ok ) does the main feed to this fuse come from the light switch Thanks Alan

 

No, power is Hot all the time battery is connected. power wire comes off tap connector below master cylinder. a few heavy red wires connected together.

 

4-Vettes,
I have a '72 coupe with the same dash/gauge light problem. I have a new headlight switch and the 5 amp fuse tests good. I have not tested the 5 amp fuse holder with the battery hooked up. I read a post that said, both sides of this fuse holder is Hot when the battery is connected. Could the tap connector you mention be another problem or the red wires?
thanks for you help.

 

Past Forum Member discovered that his car has corrosion between the large multi wire connector and the fuse box. I know the fuse box is in a difficult position, so this should be your last option. You should obtain a wiring schematic for your car. Use Google as they were offered on the Forum previously.

 

Eliredanblack,
Is this large multi wire connector located under dash near the fuse panel? if not, where is the multi wire connector located

thx

 

I believe that the multi wire plug is “plugged” into the back of the entire fuse box. BEFORE you touch the fuse box, spend some time and Google information about the fuse box/connector issues. I have found that spending time reading is extremely important before tackling a job on our old cars. The post I recall mentioned corrosion was on the connector that affected only certain pins ie. fuses/systems. The wiring diagram will let you the color of the 12 volt wire. I like to use a straight pin inserted into a wire (attached to a volt meter) to see if voltage is present. Trying to skin or remove the old/ hard plastic insulation is a bear. First see if you have 12 volts going to the lighting fuse connector, if the wire going to the lighting fuse does not show 12 volts, then t look on the wiring schematic to see where it’s connected. Remember that one wire is bringing 12 volts to the fuse then after the fuse the 12 volts is routed to the lighting.

 

thank you so much for all the info in your response for my dash/guage problem. I looked, up thru goggle, wiring schematic's and realized I don't know anything about electrical systems. I tried to fine a 1972 Corvette schematic that talks to what you said in your response. What I got back was a complete wiring harness replacement kit.
But, thanks again for your help. I'll try and figure out some other way to attack the problem.
pjc

 

Sorry that I was so long winded (as usual) in my reply. If you have a volt meter set it to read dc volts (you can test settings by reading a common 9 volt or AA Battery). Touch one lead to the brass fuse holder and the other to a good ground, see if you get voltage. Next do the seem exact thing for the other brass fuse holder. You should get a 12 volt reading on ONE of the brass holders. I let us know hat you find out, if you don’t get voltage on either fuse holder the problem is with the wire/connector supplying voltage.

 

To all my forum friends that have tried to help me with the interior lights issue on my "72 . I've tried all of your suggestions to no avail. The last attempt was running a separate jumper wire from the positive on the battery directly to the left side of the fuse and fuse holder. With the car running and the headlight switch on and rheostat turned on, none of the interior lights came on. I'm have run out of ways to try and fix these lights. If any of you have another thought on this issue, please let me know.
I guess I'll be limited to daylight driving.
thx for all your help.
pjc

 

Were you ever able to use a meter to test for positive voltage present on either side of the fuse? My guess with your attempt to run a
temporary positive wire from the battery would indicate that the Ground Circuit going to the interior lights is not present. You will need to get a wiring schematic for a 1972 year and see the color and location of the ground circuit for the interior lights. I could look at my 73 wiring schematic, but I have no way to know if is the same as a 72 car. There is a Forum member, Papawana that has a good number is schematics, try and pm a message to him. Without the correct 1972 schematic, it would be impossible to know where the grounding circuit is located. To test my theory on the ground circuit, take your temporary wire and connect one end to the negative battery terminal. The other end of the bare wire should be touch to the GROUND part of the bulb or holder. The courtesy light / bracket under the passenger map pocket is easy to access. Remember you DO NOT want to touch the positive wire or connection on the bulb holder. By the way, have you ever inspected the light switches in the Front door jambs? Let us know what you find. Good Hunting

 

thx for your quick response. I did check the voltage at the fuse and got no reading. I just send Papawana a msg like you suggested (thx again),
Front door jamb light switches?? Are you talking about the courtesy lights? If so, I've had a problem with the driver side assembly. The spring and pushrod came apart and I had to reconnect it. The courtesy lights all work now.
Waitng on a response from Papawana.

 

PJC
First off, I will let you know that I am a pretty old guy! I was thinking problem was with the Courtesy Lights per the original thread starter. I just read your post again, and now realize your problem is with the Gauge Lights, dumb me. Are you sure that the large plastic connector is properly seated to your new head light/gauge/courtesy light switch? I changed out my bulbs to LEDs and didn’t remove the headlight switch, because of the tight fit, I didn’t get the plug on the switch correctly. None of my gauge lights came on. I had to remove the instrument panel and the switch. Are you 100% positive that the plug is correctly seated on the headlight switch? Did you make sure to reinstall the ground piece of metal that comes off the old headlight switch? Go to Willcox Tech site and read about problems with restoration headlight switches. I will take a look at my schematic to see the wire colors.

 

Eliredandblack,
Tried the jumper from the negative side of the batt. Searched for a ground near the passenger side courtesy light. what I found was a courtesy light connector with 2 wires (white and grey) molded into a plug that holds the lamp. An air conditioner duct is in the way of finding a ground, if it's behind this duct. could not find anything that looked like a ground point. Then, I tried a different setup with the jumper from the negative batt to a bolt under the steering column. Thinking the all metal structure would be a ground. None of this worked.
So, hopefully Papawana will respond to my inquiry on the interior lights. Locating the proper grounds is crucial. I sent him an email on Sat.
thx again for helping.
pjc

 

PJC
Please read my post dated 8/21/22. I didn’t realize that your issue was with gauge lighting. The original poster had Courtesy Light Problems. When you read my 8/21/22 post there are a few things to check. I am sorry that my comments prior to 8/21/22 were dealing with no courtesy lights.

Check the connector that goes to the new switch and read my post. I don’t believe the problem causing no gauge lights is from a ground issue. The speedo/tach have their own ground, they are black wires that attaches to the back of each unit. The center gauge cluster has its own ground and for both to be defective would seem unusual. When you replaced the headlight switch, did you attach the metal arm that makes (ground) contact with the metal back of the speedometer? I don’t know if the wiring schematic will be much help. Read my post and let me know what you find.
Eli

 

Have you tried twisting the headlight switch? Sometimes it's turned down all the way, or corroded.

It couldn't hurt to put in new, clean fuses, and clean the contacts. I've "healed" my car by doing this before (though it is easier with the ATC/ATO fuses in 79-82).

Here are some wiring diagrams. And you can PM @papawana for a copy.

http://wordpress.keystonestatecorvet...m/?page_id=118

 

Eli,
I will take another look at the new headlight switch and its connector. I also will check the metal ground strap that goes around the headlight switch. and goes to ground.
will let you know what I find out.
thx again for your help
pjc

 

bikespace
I installed a new headlight switch last month. everything works (headlights, parking lights and courtesy lights) but not the interior lights (speed-0, rpm, all the gauges).
I will try all that you suggested with respect to new fuse and clean contacts.
thank you for the schematics. I will print them out.
I do have a question. My car is a '72. is there any info that tells me where and what the grounds are look like (pictures/drawings) for the dash and gauges?
I've sent Papawana an email last Sat.
thx
pjc

 

Do you still have the old switch? I don't know how hard it is to switch the connector around, bur perhaps you can try the old one without removing the dash.

You could also see where the potentiometer is in the headlight circuit, and see if the new switch does the same thing. If you have a multimeter...

It is not uncommon for new parts to be bad out of the box, and headlight switches in particular are notorious for this.

 

PJC
i don’t know of any place on the wiring Schematic that indicates where the ground wire/wires are attached to some metal, body part, or something else. All gauge lights are feed by (20 -Gray positive) page 12-79 and the entire metal gauge cluster has 2 (14-BLK) ground wires page 12-80. Looking at the fuse box, the left metal fuse clip should read 12 volts positive ( you can use a test light with one probe on the left fuse holder and the other probe to a Known Ground, any metal part under the dash. If you don’t have positive voltage from the left fuse clip, then you will need to go the the plastic connector at the headlight switch. Looking at my photo, the PNL LP Fused should have positive voltage WHEN the headlights are ON. Are you absolutely positive that the plastic connector is Correctly seated to the back of the headlight switch??? As I may have mentioned before, I did not put the connector on all the way, and none of the instrument lights came on. Please check to see that you have the connector correctly mounted on the headlight switch. Let us know after you look at the connector/ headlight

20-Gray positive Illuminate LP to each gauge bulb.

Inst cluster GRD. They are two spade lugs attached to the back of the metal gauge cluster

Here is the headlight switch. 1 is positive from the battery. 2 PNL LP Fused (panel lights). With the headlight switch ON there should be positive voltage at PIN number 2,
switch.

 

bikespace, I have the old switch, but it was working just like this new switch.
it's really hard to get into the space where the headlight switch mounts. I can get to the electrical connector that plugs into the switch.
I'll will try and get to it in a few days. Note. I'm not electrically inclined so it's a struggle for me.
I hope your last sentence about "out of the box" parts does not prove out to be true.
thx,
pjc