Back up Lights

[Donald H.]

Re: Back up Lights

Did you have the backup lights on when you tested, I.e. in reverse and key on? They need to be to check the hot circuit.

For your other question. I've had the rear valance off my 66 a couple of times recently for painting. I had to remove the exhaust tips to get off.

[Don Z.]

Re: Back up Lights

Donald, Ohhh..no I did not have my switch on and back up lights turn on.
This morning I did it again with switch on and back up lights on.
I did the test set on 20volt setting. I got a reading jumping from 1.65 -1.75.
I am assuming this is not even close.
So with all of this testing, what are you seeing? Ground problem at the socket or ground problem at the wire ground??
As I said prior..know next to nothing about this electricial stuff.

So, how do I proceed other than taking off the ground wire and cleaning it so a good contact...but what about the socket??

Another question: Is there a ground wire on each back up light or only one for both??

[Paul J.]

Re: Back up Lights

Donald, Ohhh..no I did not have my switch on and back up lights turn on.
This morning I did it again with switch on and back up lights on.
I did the test set on 20volt setting. I got a reading jumping from 1.65 -1.75.
I am assuming this is not even close.
So with all of this testing, what are you seeing? Ground problem at the socket or ground problem at the wire ground??
As I said prior..know next to nothing about this electricial stuff.

So, how do I proceed other than taking off the ground wire and cleaning it so a good contact...but what about the socket??

Another question: Is there a ground wire on each back up light or only one for both??

OK, I'm back in town for today. Your ground is bad. It can be at the socket or anywhere along the wire, most likely where it enters the harness or connects to the frame (I forget where the other end goes). Try this, while your holding the test leads on the contacts at the socket, have someone reach under the car at the socket and move the wires (a lot). If you get a reading, then the contacts in the socket are bad. If you don't get a reading then move down the wire. My bet is that you don't have good contact either at the socket or at the other end of the wire.

Paul

[Donald H.]

Re: Back up Lights

First, just to make sure you are using your meter correctly, if you have it set to 20 volt DC setting and your probs plugged into the V (volts hole) and COMM hole, touch to a know DC power source. Anything will work, i.e. flashlight battery, or even the car battery. If you use a flashlight battery you should get something close to 1.5 volts. And of course with the car battery you will get something like 12 volts or likely a littler higher if you have a good battery. If you are sure your meter works and you are using it correctly, I'm not sure how you would get 1.65. I've attached a picture of my meter connected to a 6 volt DC battery. Note the probs are plugged into V and COMM, dial is set to 20 Volts DC and the meter is reading 6.23 Volts.

Each of the lamp assemblies has it's own ground wire. You can do another ground test without power. I'm not certain, but pretty sure that the ground wire goes to the lamp assembly and not directly to the lamp socket. I believe the ground wire has a round wire lug that attaches on the assembly mounting stud, thus the whole assembly is grounded.

Put your meter back into continuity mode and see if you have continuity between the lamp housing and the bumper, bumper bracket, or some other good ground source. As you saw in the picture I posted earlier I checked continuity from one of the lens screws to the bumper. This should tell you if you have ground to the lamp assembly. Then test again by just touching the lamp socket (the outside shell of the socket). If you get continuity to the assembly and not to the lamp socket then I would suspect corrosion between the housing and the socket as I had with my license plate lamp.


Meter test.jpg

[Don Z.]

Re: Back up Lights

WOW, this is going to take a little thought on my part to coup what has been said. I guess to do what you said Paul, I will wait until after Carlisle and vacation after I have removed the lower panel. Will be much easier to get up in behind the sockets. Of course I need to convince my wife to do the wiggling. I had my hand up in there the other day and almost lost it. Will be much easier with the panel off.

Donald I'll need to print off you suggestion and re-read it a few times, then see if I can get to work on that tomorrow. Guests coming this PM and then tomorrow is getting ready for Carlisle.
I'll get back after I try those things.

Again, thank you all for your help.
I hope eventually to get this problem solved.

[Don Z.]

Re: Back up Lights

Ok, Donald...I printed off your instructions and decided to give them a quick try this PM. Thank you for making them very clear for a dummy like me. Here is what I got.
Plut probs in V & COM. Set to 20volts. Tested a "D" size flashlight battery. I got 1.58 volts.
Next I set to continuity. ( remember my instructions say it will beep)
I did as you had done in your photo. Red to lens screw & black to bumper..continuity...beeped loudly.
Next, I put red on outside edge of the socket and ground to bumper...NOTHING

I then did something not in your notes.
I put the bulb in. I touched red to the outside edge of the socket, not touching the bulb ( I hope) and black to bumper....continiuty..got beeping.

I do believe you are correct as what I can see with flashlight and mirrors that the ground is on the top stud holding the housing.

So, as not to be so bold doctor. With these test results, what is the determination???

Thank You Donald.

[Paul J.]

Re: Back up Lights

Ok, Donald...I printed off your instructions and decided to give them a quick try this PM. Thank you for making them very clear for a dummy like me. Here is what I got.
Plut probs in V & COM. Set to 20volts. Tested a "D" size flashlight battery. I got 1.58 volts.
Next I set to continuity. ( remember my instructions say it will beep)
I did as you had done in your photo. Red to lens screw & black to bumper..continuity...beeped loudly.
Next, I put red on outside edge of the socket and ground to bumper...NOTHING

I then did something not in your notes.
I put the bulb in. I touched red to the outside edge of the socket, not touching the bulb ( I hope) and black to bumper....continiuty..got beeping.

I do believe you are correct as what I can see with flashlight and mirrors that the ground is on the top stud holding the housing.

So, as not to be so bold doctor. With these test results, what is the determination???

Thank You Donald.

Don, you had already done all of the tests that you needed to do yesterday. Reread post #18. Your ground is bad. The reason for the low voltage reading before is that the ground is just barely making contact, probably from corrosion as Donald previously mentioned.

If you want to continue to play with it, put a bulb in the socket, turn it on, and touch a wire from the metal edge of the socket to the bumper. The bulb will light up, indicating the bad ground.