1968 Cutlass convertible
Rear Bumper Running Lights not working

But.. these do work
Both rear panel marker lights are working
Turn signals both sides and emergency blinkers as well as brake lights are working

No fuse blown and the ground is attached just fine near trunk latch.

I'm stumped! I really appreciate all members here for the love of the Olds'

 

The turn signals/brake lights use a separate filament in the 1157 bulbs and totally separate wiring from the tail lights. Do the front parking lights work? Does the license plate light work? If so, the problem is all the tail light filaments are burned out (possible but not likely). If the license plate light is also not functional, the problem is most likely in the brown wire somewhere between the headlight switch connector and the rear of the car. FYI, this is all shown in the wiring diagram in the 1968 Chassis Service Manual.

 

thanks for taking the time sir....
I do have the service manual
The plate light works as well as front parking lights
the bulbs 1157 are all new

 

If the license plate light works, then you have power to the back of the car. Use a test light to probe the tail light sockets and see if you have power on the terminals. If so, the bulbs are defective. If not, figure out where the break is. There's a splice in the harness where the one brown wire from the front is split out to feed the tail lights and license plate light. That would be the most likely candidate.

 

much thanks..... I'll get on it today and let you know

again.... thank you

 

Are we talking about just the back-up lights mounted on the rear bumper? If so, it could be the housings for the bulbs need to be cleaned out to establish a good ground. Or it could mean that your neutral safety switch is bad. Both are what happened with my '69.

Randy C.
'68 4-4-2 convertible
'69 4-4-2 convertible

 

He's talking about the rear "running lights", which I assume to be the taillights.

 

I'm wondering if maybe OP thinks the backup lights are supposed to be on all the time?

 

The only reason I thought about back-up lights is because the OP refers to "rear bumper running lights not working" and continues to say that everything else in the back end works.

Randy C.

 

Joe,

Nice call on the brown wire...
I had to do some unwrapping of the clothlike tape and presto a kink about 6 inches from said harness.
I re spliced and connected the freshly exposed wire and presto!!!!

All lights work perfectly!!

much thanks for taking time outta your day to lend your knowledge, I'll pay it forward.....

 

I know you found your problem, but I'd just like to add...

Sometimes, the quality of the bulb will cause this, too. I thought I might need to replace a whole tail light assembly on a non-classic. Turn signal and brake lights worked, but the tail light would not stay lit. Smack the light, came on. Hit a bump, went off. I just happened to have another bulb, that had bigger contacts. Put that other bulb in, and presto... fixed. The bulb was an 1157, and once I compared the two contacts, I saw the difference. That's why certain bulbs are more expensive at the parts store.

(and the bad bulb had a good filament)