Barracuda Challenger Forum

Author Topic: Low Beam Works - High Beam Doesn't  (Read 173 times)

Offline EddieE

  • Jr. Member
  • **
  • Posts: 76
Low Beam Works - High Beam Doesn't
« on: June 05, 2017 - 09:51:47 PM »
74 Cuda with stock wiring.  Low beams work but when I hit the high beams I have no headlights.  Replaced the foot dimmer switch with a rockauto (maybe Dorman) replacement but no change at all.  The high beam dash indicator light goes on, but the headlights don't.  This is a nice, triple black never rusty Texas car but it's a driver so the only new electrical items are a new rear light harness, a new backup light and under dash reverse indicator harness for the four speed, and a new voltage regulator with a dedicated ground back to the battery.  I have stock cuda horns but they are weak so I think I may need the harness for the forward lights (which I think includes the horns).

Any insight on the immediate problem, and any thoughts on whether to just buy all the stock harnesses (at a premium price)?  I like the idea of just starting with the dash harness and fuse panel and going from there with the appropriate harnesses.  I know some modern technology, and bypassing the ammeter, are the "right" way if you're replacing everything, but I am willing to spend a little more so that everything matches the original wiring diagrams.   BTW, I have a classiccarwiring.com wiring diagram and it's very helpful (not a plug just a fact from a wiring neophyte).

Any help would be appreciated, and if you are local you can come and fix it while I watch and drink beer.





Offline GoodysGotaCuda

  • Sr. Resident
  • ******
  • Posts: 5190
Re: Low Beam Works - High Beam Doesn't
« Reply #1 on: June 05, 2017 - 10:00:43 PM »
You have voltage going to the dimmer and out of the dimmer since the low beams work and the high beam indicator works.

What you don't know is where it is going from there. The wires go through the firewall bulkhead connection, which could be faulty/corroded/weak and then onto the headlights.

If you have power at the headlight when the high beam switch is on, then you have a bulb or ground issue.

If not, I'd investigate the bulkhead connection.
:working: Build Page: Goody's 'Cuda Build Page :working:

2016 Subaru WRX
2016 BMW X1
1976 Dodge Warlock
1972 Barracuda - 5.7 Hemi + T56 Magnum - In progress


Wheel & Tire Specs:Link
Aftermarket Gauges:Link

Offline EddieE

  • Jr. Member
  • **
  • Posts: 76
Re: Low Beam Works - High Beam Doesn't
« Reply #2 on: June 05, 2017 - 10:09:15 PM »
Thanks.  I think all bad things are going to trace back to that bulkhead connector and all of the veteran wiring going in and out.  Am I nuts to just start there as the "constant" in the equation?  I've had the dash out before as I started the conversion to Vintage Air and installed the vents and evaporator.  I'm still procrastinating on the other side of the firewall.

I feel like the stock wiring harnesses would allow me to do it myself, so maybe the additional parts cost could be offset by my own labor.  Misguided?


Offline GoodysGotaCuda

  • Sr. Resident
  • ******
  • Posts: 5190
Re: Low Beam Works - High Beam Doesn't
« Reply #3 on: June 05, 2017 - 10:12:39 PM »
Thanks.  I think all bad things are going to trace back to that bulkhead connector and all of the veteran wiring going in and out.  Am I nuts to just start there as the "constant" in the equation?  I've had the dash out before as I started the conversion to Vintage Air and installed the vents and evaporator.  I'm still procrastinating on the other side of the firewall.

I feel like the stock wiring harnesses would allow me to do it myself, so maybe the additional parts cost could be offset by my own labor.  Misguided?


A lot of demons feed off of the bulkhead connection. I can't speak for what the best options out there are, I have about 12" of factory wiring left in my car.  :icon16:
:working: Build Page: Goody's 'Cuda Build Page :working:

2016 Subaru WRX
2016 BMW X1
1976 Dodge Warlock
1972 Barracuda - 5.7 Hemi + T56 Magnum - In progress


Wheel & Tire Specs:Link
Aftermarket Gauges:Link

Offline EddieE

  • Jr. Member
  • **
  • Posts: 76
Re: Low Beam Works - High Beam Doesn't
« Reply #4 on: June 05, 2017 - 10:13:53 PM »
I assume that's your phone charger!

Online 1 Wild R/T

  • Resident
  • *****
  • Posts: 3986
Re: Low Beam Works - High Beam Doesn't
« Reply #5 on: June 05, 2017 - 10:38:08 PM »
Turn the headlights on, high beams on, point car at a wall so you get visual feedback, wiggle bulkhead connector.... No change look elsewhere first, wouldn't be the first time the bulbs were all burnt....
JS27N0B 70 Challenger R/T Convertible  FJ5 Sublime, Show Poodle w/75,000 miles since resto
WS27L8G 68 Coronet R/T Convertible  PP1 Bright Red, Project
RM21H9E 69 Road Runner Coupe R4 Performance Red, Sold...
5H21C  65 Falcon 2 dr Wagon... Dog Hauler...

Offline EddieE

  • Jr. Member
  • **
  • Posts: 76
Re: Low Beam Works - High Beam Doesn't
« Reply #6 on: June 05, 2017 - 11:39:51 PM »
Will do.  Do I need an an asbestos glove to wiggle the bulkhead connector, or should I just have my wife do it?

Online 1 Wild R/T

  • Resident
  • *****
  • Posts: 3986
Re: Low Beam Works - High Beam Doesn't
« Reply #7 on: June 05, 2017 - 11:49:00 PM »
Will do.  Do I need an an asbestos glove to wiggle the bulkhead connector, or should I just have my wife do it?

Man up!! Let your wife do it..... :roflsmiley:
JS27N0B 70 Challenger R/T Convertible  FJ5 Sublime, Show Poodle w/75,000 miles since resto
WS27L8G 68 Coronet R/T Convertible  PP1 Bright Red, Project
RM21H9E 69 Road Runner Coupe R4 Performance Red, Sold...
5H21C  65 Falcon 2 dr Wagon... Dog Hauler...

Offline jimynick

  • Resident
  • *****
  • Posts: 3770
Re: Low Beam Works - High Beam Doesn't
« Reply #8 on: June 05, 2017 - 11:52:32 PM »
Will do.  Do I need an an asbestos glove to wiggle the bulkhead connector, or should I just have my wife do it?
LOL, that depends on what the settlement her lawyers going to draw up looks like.  :stirpot:

Offline EddieE

  • Jr. Member
  • **
  • Posts: 76
Re: Low Beam Works - High Beam Doesn't
« Reply #9 on: June 06, 2017 - 12:21:51 AM »
It could be worse.  She could actually fix it and I'd be trapped in Blabbermouth Junction for life! :roflsmiley:

Offline EddieE

  • Jr. Member
  • **
  • Posts: 76
Re: Low Beam Works - High Beam Doesn't
« Reply #10 on: June 08, 2017 - 12:34:41 PM »
I think I found the problem. I pulled the headlights and I'm getting 11.9 volts at the high beam headlight sockets (engine off) so that leads me to believe that the forward light harness and the overall wiring in and out of the bulkhead connector is pretty good for being original.  I had an intermittent overcharging problem a while ago that I fixed by replacing the voltage regulator and running a ground directly from the regulator mounting bots to the battery negative. BUT, before I fixed it the overcharging was pegging the amp gauge at any revs over 2500 so when it happened I was using the bright lights to use up some of the amperage. RESULT, I think I burnt out both of the high beams in the sealed beam headlights.

That's a hell of a coincidence, and it must have happened during the day or I would have noticed it. I reached this conclusion because I tested the continuity on the sealed beams and the low beam circuit beeped and the high beam circuit didn't (on both bulbs). I ordered some new headlights and we'll see if I'm right.

I'm going to order a headlight relay kit from crackedback.  Guess I'll get some electric heaters to use up the amps next time it overcharges. :dunno:

Offline crackedback

  • Jr. Member
  • **
  • Posts: 151
Re: Low Beam Works - High Beam Doesn't
« Reply #11 on: June 08, 2017 - 12:44:30 PM »
The high beam burning out from the overcharge happens sometimes.

I sent you a PM on a headlight to look into that is inexpensive.  Look for them on amazon, sometimes they are in the $7 range or less. 

Glad you got the high beam situation figured out.

Offline TelisSE440

  • Sr. Member
  • ****
  • Posts: 1722
Re: Low Beam Works - High Beam Doesn't
« Reply #12 on: June 08, 2017 - 02:56:43 PM »
Glad everything worked out  :thumbsup: And with no collateral damage (wife)  :lol:

Offline EddieE

  • Jr. Member
  • **
  • Posts: 76
Re: Low Beam Works - High Beam Doesn't
« Reply #13 on: June 08, 2017 - 07:15:33 PM »
Good one