Back up lights on a 68'

[jlangholzj]

well fellas, I've done a tick of searching, and from what I've found, the switch for the reverse lights and the neutral safety switch are one and the same. if not, both are located on the LH side of the trans. My car has a automatic, C4.

both of my bulbs are good, and am I right in assuming that they travel underneath the door (inside near the rocker panel-ish area) and then were do they go after that. I have a shop manual, but its worthless for this.

thanks guys,

-john

 

[BarnStang]

Backup lights from the trunk, over the left rear wheelwell, through the front of the qtr pnl, along the top of the left rocker (under the left sill plate, up the let kick panel, into the main harness, out the firewall at the top center where the neutral safety loop, and the back up lights are combined into a square 4 connector plug, that mates with the harness from the neutral safety switch on the side of the C-4
You can test the back up lights by puling the plug apart, and jumpering the two wires together at the plug exiting the firewall. I'll see if I can find the correct color code so you know which two wires. THey will both be the same color code. I'll post in asec unless someone else does faster...

Actualy it's not dead center in the firewall, it's closer to the driver sid. Near the back of the valve cover...

 

[BarnStang]

Jumper the Black with red stripe wires together. THe back up ;ights should come on. If not, need to start working your way back. THere is a fuse too. Try that first. Let us know i you get back up lights. If you do, then it's a neutral safety switch problem. It may just need adjusted. You can check this by having someone watch and moving the shifter slowly through the range between park and neutral and see if the back lights come on at some point in the travel. If they do, the switch on the side of the transneds to be rotated slightly to get it back in line. THere are nuts that hold itin place. It will move in both directions slightly.
Oh, you ned the switch on to see the back up lights in any of the tests I descriped.
I'm gussing tha the fuse that feeds the backup lights is in the lower right hand corner of the fuse box. Check the labels on the fuse box to be sure.

 

[Iamdiffrnt]

The only thing I want to add is that on the 68 they are two 2 pin connectors instead of one 4 pin, other than that, BarnStang sounds right on.

 

[jlangholzj]

thanks barnstang. Thats about the description I needed. I'll check the fuse, but I have done the cycle through the shift w/the lights off in the shop to see if they light up. no luck. If the fuse is good, I'll try to work my way back.

could you take a pic of where it comes out of the firewall? or is it so obvious that I could find it at first look??

also, is there a way i can test the neutral switch?? it will start in neut, but is there some other way to make sure that It's functional??

thanks again fellas.

 

[BarnStang]

You will be able to see the two connecters. Unplug the connecter with the black w/red strip wires. Jumper the connector terminals on the plug exiting the firewall. Turn the switch on and see if you have backup lights. Let us know. If not check the fuse. If the fuse is blown, and you replace it and it blows again, you're stuck tracking down the short. If the fuse is good and no lights. Check to see if you have 12v on one of the two terminals on the connecter exiting the firewall. Let us know what you come up with.

 

[JDS68Stang]

If you do need to replace that neutral safety switch, it's a simple fix, they cost around $23.00.

 

[Rusty67]

If you want to test the neutral safety switch just get a test light or a multimeter and then disconnect the plug in the engine bay. Put the car in reverse as see if you get anything from the pair of wires for reverse. They should make a circuit. Double check your fuses and bulbs just to be sure everything is working.

Reverse lights don't run through the headlight switch as far as I know.

 

[jlangholzj]

fist of all , thanks guys.

yeah it is that obvious.. DUUUURRR !

when i got home today, I cycled trought the shifts with the switch plugged in , and there was no lights.

-I replaced both of the bulbs previously this year, their both good

-I did quick pull the plug next, I jumped the wires quick, and no lights.
*****I used a simple light tester (one with a bulb) and I do have power at the plug******

-all of my fuses are good.

BTW*** it is a 4 plug-er, im my car anyway.


I have a few questions on how to go about testing the switch.

I probally won't have time to work on it till this weekend, but I have a few ideas.

1) I'll Jump the wires, and test the wires in the trunk to see if i have juice back that far, If not, I probally have a short somewhere along there.

and probally goof around with it abit.

2) I'll pull the plug, and apply power to the nuetral switch, and cycle through the shifts to see if the switch is any good. If not, well then ....THEre's your PROblem!..



any other ideas??

thanks again guys,

-john

 

[BarnStang]

Hmmm, need to keep things straight. If you have 12 volts power in one side of the plug from the firewall, but no lights, the problem is between the trunk, and the plug.
Make sure you understand the circuit you are working on. When you seperate the plug at the firewall, one side goes down to the switch on the trans. The other side is the power and the lights. Unplugging the connector simply removes the neutral saftey switch from the circuit. Moving the shifter with the plug disconnected will have no effect at all. If I understand what you wrote, if you proved that you have 12 volts, and you shorted the two terminals together, the black with red strip wires, and no lights, then the neutral safety switch is no longer a concern. You can test that later once you get the backup lights working.

When you seperate the connector, one side goes into the firewall, the other end goes down to the transmission to the switch. Pull the connector apart. Set the one end aside that runs down to the trans. Take the other conector in your hand and identify the two black with red stripe wires. Short these two wires together and see if the back up lights come on. You may have done it that way, but from what you wrote, it wasn't clear. Let us know what you get with that test first.

IF, and only if, the lights come on, the problem lies with the switch on the trans.

If they do NOT come on, verify again that one of the two wires has 12 volts (good test light indication) on it. Again, make sure you have the ign switch in the ON position or the ACC position.

If you have a good test ligt indication, leave the wires jumpered. Go to the back up lights and make SURE the bulbs are good. Pull the bulbs and CAREFULLY probe the center contact and see if you are getting 12 volts to the center contact in the bulb socket. You can tape up the probe to make sure you don't short out the circuit and blow the fuse.

If you have a good test light indication, check the bulb. If not. Write back, there are two other places that the backup lights can be disconnected. We can get to that later.

 

[jlangholzj]

***I edited my previous post to clear things up, it was a little confusing****

yeah, i do realize that as soon as I disconnect the plug, the neutral switch is no longer a factor. If you jump the wires, the lights should come on. My point was that I want to test the neut switch also,(probally with a ohm meter) just in case I have more than one problem here.

Because, if it is SHORTING somewhere and the fuse serves its purpose, it would blow. So If I'm jumping the wires and no lights, with a intact fuse, Something else might be wrong there.

Jump and test the socket will probally happen tonight.

 

[jlangholzj]

I rejumped the wires, and no lights. Unfortunately, I didn't check it with a multimeter yet, but there is power there, I just don't know how much.

Also....

when the plug was disconnected, I checked the neutral switch with a Ohm Meter, I was testing while dad shifted through the cycles, and at no point, was the circut completed, I had full resistance at all times. does this mean that my siwtch is bad??

 

[BarnStang]

It would be odd that you have two problems...it would mean that the switch is bad. You should have continuity on the Black w/red strip wires in reverse, and continuity on the red w/black stripe wires in park and neutral. If the car starts and runs with the plug conncted, then the neutral part of the switch is good, and your test is not being done right. Actually, it's just the start circuit-ign sw, connector, neutral safety sw, solinoid. So if it cranks at all connected, then check how you are doing the test.
If no lights with the connector jumpered, and the ign switch is ON or ACC, there are a couple conections. THere should be two pigtail connectors for each backup light in the trunk. One is 12 volts from the connector at the firewall, and a pigtail connecter for the ground in the trunk. Look at the taillights. THere should be a harness dropping off to the bottom of the qtr pnl. Check these pigtails and make sure the ones that are tied to ground are good and tight and clean.
There is another connector at the drivers side kick panel. If you remove the kick panel and contort yourself, you will see the trunk harness coming out at the top of the kick panel. THere are several conectors. One should amazingly enough be a black w/red strip wire. Make sure this connector is tight.
If you do have 12 volts at the conector on the firewall, and no 12 volts at the bulb sockets, or at one of the pigtails in the trunk, you can split it here and check for 12 volts. Let us know what you find from there.

 

[jlangholzj]

You should have continuity on the Black w/red strip wires in reverse, and continuity on the red w/black stripe wires in park and neutral. If the car starts and runs with the plug conncted, then the neutral part of the switch is good, and your test is not being done right. Actually, it's just the start circuit-ign sw, connector, neutral safety sw, solinoid. So if it cranks at all connected, then check how you are doing the test.

elaborate on this a little more...



before testing it, I touched the leads of the ohm tester together, yup the tester works.

after I unplugged the switch, I touched a lead to each of the black w/ red stripe wires. If I am correct, these are the two wires for the backup switch. If at any point it completes the circut, It would ohm out, showing 0 resistance. proving that the switch is in fact good. Just for giggles I'll test the other side of the switch tomorrow.

thanks alot barnstang, some of this stuff can get confusing and I really appreciate the help, and from the rest of you guys too!

 

[jlangholzj]

Conclusion: It's the switch

I was FINALLY able to sit down and work on it. The problem is the switch. I was able to jumper the wires and light up the back up lights.

What the problem was is that the Driver side back-up light didn't have a very good connection. I bought some new, and brighter , bulbs and cleaned out the socket good, and viola! we have lights!!.

I also tested the switch, and again, The backup light side never completes the circut. I also tested the Neutral side, and that functions perfectly. It completed the circut in both park and neutral. sooo, I guess I'm getting a new switch.

Thanks again to all.

-john

 

[BarnStang]

Alrighty then! Since you're feeling froggy...you "can" take the neutral safety switch apart. Drill the rivits (not the plastic) and carefully seperate the halves of the switch. It's probably too far gone, but I have fixed one...someone pulled so hard on the harness that they pulled the switch apart enough for one of the contact strips to drop loose inside. Didn't break the plastic. I put some small machine screws and nuts back in place of the rivits with some locktite. THat was a 68 coupe too...it could also be a wire corroded off the contact. Can be soldered back on. Switches aren't too expensive either. Well done though!

 

[jlangholzj]

Alrighty then! Since you're feeling froggy...you "can" take the neutral safety switch apart. Drill the rivits (not the plastic) and carefully seperate the halves of the switch. It's probably too far gone, but I have fixed one...someone pulled so hard on the harness that they pulled the switch apart enough for one of the contact strips to drop loose inside. Didn't break the plastic. I put some small machine screws and nuts back in place of the rivits with some locktite. THat was a 68 coupe too...it could also be a wire corroded off the contact. Can be soldered back on. Switches aren't too expensive either. Well done though!

LMAO! sorry, but that sounds like something my grandpa would suggest. He's to tight to spen $20 on a new part, so he has to jimy rig it to work! lol. I'll probally take the old one appart once I get a new one, just to see how it works.

 

[BarnStang]

Yea, I know. THat one was an easy fix though. Usually (99% of the time) they are toast. Defintely get a new one. Will be more reliable down the road. Now you can stop backing into trees cause you couldn't see them!

 

[jlangholzj]

sssshhhh! you weren't supposed to tell anyone that!

 

[JDS68Stang]

When you replace the switch remember which way the kick down lever came off.
Your Gramps sounds like my older brother