Back up Lights

[Don Z.]

Need Help...again ! Yesterday, when backing my '66 out of the garage, my wife said "you don't have any back-up lights". I thought great.
This morning I thougth I'd check the normal stuff after reviewing my problem in the archives. Most of that pertained to the switch. I figured if I needed a new switch, Carlisle was in a few days.
I checked and replaced the fuse..nothing. I then checked the connection at the firewall from the switch to see if any corrision was there..nothing. I figured I'd change both bulbs. I did not think if one bulb went out both would not work. I changed the drivers side, went to the passengers side and the bulb was burnt. I thought..got this fixed. After changing the bulbs, only the passenger side worked. I checked drivers side what I could reach, the socket, and all the connections. No loose wires, everything tight. I tried several bulbs and nothing. I guess I did eliminate that I did not need a switch but exhaused my thoughts on what could be wrong or my next step to solve the drivers light.
Any thoughts / suggestions ?? Thank You

[Paul J.]

Re: Back up Lights

I"m not good with electrical problems, but the first thing I would check is to see if the socket has power, then I would check the ground.

[Michael G.]

Re: Back up Lights


You might go to the switch itself....next to the tranny. Possibly the linkage from transmission shifting ear to switch needs adjustment. Disconnect the linkage and move the lever on the switch back and forth to see if lights engage...turn on/off. That be the case your switch has two small screws that allow repositioning of the switch.

[Francis F.]

Re: Back up Lights

Don std. shift or P.G.?
Fran.

[Don Z.]

Re: Back up Lights

Francis, my '66 is 4-speed. At first I thought maybe a switch problem, but when I changed the burnt out bulb and it worked on the passenger side, then I felt it was not the switch.
Paul, I like you know next to nothing about electrical. What I know probably would not fill a match box.
I was given a Sears meter and know nothing about how it works. I know the pos. / neg. leads. It has a dial on for different readings but I'm lost as to what to set it on and how to check the socket for power.
What I need is a simple lesson on how to set and use it.
I too think maybe a ground. What puzzels me is they have worked for years and also just recently, then nothing.

Am I correct that the best way to access the socket and check ground connections, is to drop the back lower panel?? My arm barely fit up in there.
Thanks for the reponses.

[Francis F.]

Re: Back up Lights

Don,you can get access to the lamp socket/bulb by removing the plastic clear lens.Remove the bulb by turning ccw,you will then see a dot of solder inside that contacts the base of the bulb.with your meter set on 12 volt scale touch the red (pos) probe to that dot of solder .the other probe (black neg.) can touch the car frame/or metal bumper,at this poiin your meter should show voltage hopefully 12 volts.all this while trans is in rev.position.give it a try....Francis

[Don Z.]

Re: Back up Lights

Thank You Francis. That seems simple enough. I'll give it a try tomorrow.

[Donald H.]

Re: Back up Lights

Don, If one works then it stand to reason that the switch is OK. The other thing to check is the the ground wire at the socket. This will be the black wire. If your volt/ohm meter has a dial and different plugins for the wire leads, then you plug your wire leads into the COM (commond) and the Ohms (this is the one that looks sort of like an upside down U). Then set the dial to Ohms. I don't think the scale matters as to which setting you use. You are checking for continuity only. If you touch the tips of the lead wires together you should see the meter needle jump off zero, this indicates continuity or that you have a complete circuit. Now you want to use these leads to check continuity at the lamp socket. If you touch the leads to the outside of the lamp socket (not the inside center of the socket when testing for hot 12 vols as Francis described) and the other wire to the frame you should see the needle jump if you have continuity. Make sure where you touch on the frame you get to bare metal and not paint.

If you don't have continuity or a good ground at the lamp assembly then that lamp is not going to work even if you have 12 volts at the center of the socket.

[Tom K.]

Re: Back up Lights

Don, If your meter is like mine it probably has a 20 volt setting in the DC volt section. Be sure you use the a DC volt setting. Anything on a car is going to be DC volts not AC. AC is for your house electric readings. Do Not use any of the ohms settings to check for the presence of any voltage. You can use the ohms settings to check the filament in the bulb for continuity. Also be sure that you have the key in the on position when you are checking for voltage and you should have a 12+/-volt reading. Be sure when you probe the center contact that you don't touch the side of the socket as that is ground and will cause a short that could blow a fuse. Hope this helps.
Tom

[Don Z.]

Re: Back up Lights

Francis, Donald & Tom..1st of all thanks for the comments and help. Francis, when doing as you mentioned I got a reading of 10.35 volts. I guess this is Ok. Tom mentioned in his post 12 +/-. Of course the car was not running, ignition was on position and in reverse. This was taken with red probe on center of socket and black on inside of bumper and also on the bracket holding the muffler up.
Donald, my meter is digital. It has 3 holes across the bottom with the center hole COM. On my meter in the Ohms section it has 200, 2000, 20K, 200K, 2000K. I put leads in the black and red, but not the center COM. When touching the leads in most of the settings the meter jumped, so I figured I had continuity. I used different setting and used the inside of the bumper and the bracket on the rear of the muffler since all of my frame is painted and I found no bare metal. I put the red probe to the side of the socket. Doing this I got nothing on the meter. Now of course I did not use the center hole, COM because I did not know if I was to use the red or black in there.
I guess what you are saying is since I don't have continuity ( if I tested it correctly) then I most likely need to remove my rear panel so I can reach, review and check/clean the ground wire/screw? I think that is on the bottom. Mayby I can reach it without removing the panel.
Donald, If I used the meter wrong, maybe I did not follow / understand your instructions.
Again, all your help appreciated.
Since I am leaving on vacation after Carlisle, the removal of the panel, etc. will need to wait a few weeks.

[Paul J.]

Re: Back up Lights

Don,

Francis' test takes the socket ground out of the circuit, and tells you if you have power to the socket. Your results show that you have. Check the ground by touching the red probe to the center of the socket, just as you did before, but touch the black probe to the side of the socket (be sure the probe ends do not touch each other). If the ground is good, you'll have a reading of close to 12v, if it is not good, then there is no reading and the ground wire in the socket or somewhere else is not making contact.

Paul

[Donald H.]

Re: Back up Lights

Pauls recommendation checks the complete power circuit to the lamp. I was just checking if you have a ground at the assembly. Here's a picture of my 66 backup lamp. I'm doing a simple test to verify ground at the assembly. Of course that doesn't necessarily mean you have ground at the socket. If the socket has corrosion between it and the housing you could have broken ground.

I had a similar issue with my license plate lamp. I had good ground to the assembly housing that the black ground wire was connected to, but the lamp socket was not grounded even though it is essentially riveted to the housing. I ended up soldering a small spot between the housing and the socket before I ever got a good ground.




Back up light ground check.jpg

[Don Z.]

Re: Back up Lights

Ok, Paul and Donald. I understand what you are doing. Paul, do I do your test with the back up lights on or off??? Tom said earlier with back up on, don't touch the side, that it would short.
I'll be doing this in the morning..will let you know how I make out.

[Joe R.]

Re: Back up Lights

Don,

I would recommend doing as much as possible with power off. Certainly you can check to see if the ground is good with power off. Just put your meter in Ohms mode (continuity check), look for close to zero Ohms between a known good ground and both lamp sockets.

Joe

[Don Z.]

Re: Back up Lights

Hello All...again thanks for all the help. I did the test this PM that Paul suggested, red probe to center & black to the edge. I got no reading at all. So I guess this suggests there is a ground problem either in the socket or the ground wire.
Am I assuming this correctly??
Also Donald I re-looked at the continuity test you mentioned. I happen to have a setting ( di dnot see before )on my meter just for continuity. If I touch the probes together it buzzes. I did your test and got no buzzing. I don't know if this is good or bad.
So gents, sounds as though there is a ground problem. A hunting I must go but not until after Carlisle. Don't need back up lights at Carlisle anyway.

Another question: I've never had the back lower panel off ( except when being painted). Do I need to remove the exhaust tips or will it slide off under the lower bumpers and over the tips???
Again a big thanks to all for you help.