1. Registration trouble? Please use the "Contact Us" link at the bottom right corner of the page and your issue will be resolved.
    Dismiss Notice

Headlight delay?

Discussion in 'Intermediate CJ-5/6/7/8' started by 73cj5, Feb 8, 2006.

  1. 73cj5

    73cj5 Member

    Sometimes when it is cold outside my headlights take a second to turn on, or sometimes they won't turn on until i blip the throttle. Has anyone seen somthing like this before. The only thing that might be wrong with the electical system is the headlights dim a little at idle but become brighter when i rev the engine.
     
  2. AeroE

    AeroE New Member

    The battery is cold and has high internal resistance and is also probably on its last legs, and the voltage regulator ain't regulatin'.

    There is an outside chance that someone installed a generator, I suppose - generator output is sensitive to rpm, hence alternators came along to replace them.
     
  3. 73cj5

    73cj5 Member

    Is there a relay in the headlight circuit?
     
  4. w3srl

    w3srl All-around swell dude Staff Member

    Not stock, I don't think. Up until '74 the electrical systems on Jeeps were still pretty primitive. In addition to the aforementioned items, I think I'd take a look at the headlight switch, and maybe replace it. They're not expensive, and a lot can go bad/get worn in 30+ years.
     
  5. 73cj5

    73cj5 Member

    I'll try that, having the headlights refuse to turn on would no be fun.
     
  6. timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

    Old vehicles seem to have a lot of problems with bad grounds. This goes along with rust and corrosion especially. I'd expect that the headlights are grounded through the body and back to the battery through the lead from the fender to the negative battery cable. If this path has a higher resistance than normal, you would see headlight brightness that depends more than usual on the engine speed.

    On my '73, I had aftermarket headlights, and I installed a relay between the headlight switch and the lights. As I recall, there was no relay on the headlights from the factory.

    I would also check that all the connections are solid and the grounds good in the regulator-alternator charging circuit.

    Another possibility - does the '73 use the same thermal cutout in the light switch that the earlier Jeeps use? I thought I read here that part of the circuit is protected by a thermal breaker in the light switch on earlier Jeeps. The separate fuse box didn't happen until 74 or 75 - IIRC the '73 has just a few inline fuses, like the earlier Jeeps. Perhaps the switch could be getting flakey?
     
  7. 68 CJ

    68 CJ Banned

    Yup, start with the grounds and also the relay contacts. I figure your pushing enough volts when you rev, I suspect the relay contacts. Run a wire from the ground side of the lights to the battery ground. If it is a ground problem, everything will work right. If your losing volts due to a broken wire(near open condition) you may be going past it also when voltage is applied. Get the headlights on, then move a few wires around, if you find the open or possible short, your lights will go dim or out. Wiring, oh what fun...
     
  8. sparky

    sparky Sandgroper Staff Member Founder

    MOP's thermal cutout was strictly a worn out ignition switch that didn't make the proper contact for the accessories until it warmed up. ;)
     
  9. w3srl

    w3srl All-around swell dude Staff Member

    Um, I forgot that the stock headlight switch also had a thermal breaker attached to the back of it, and those tend to wig out after they've been in service for a while. I'm still betting on the headlight switch itself though, and the likelihood that "blipping" the throttle bumps the charge amperage enough to overcome the worn/dirty contacts in the switch. If the wiring harness is still intact, the headlight switch and the brakelight switch are the two weak links in the original lighting circuit IMHO.
     
  10. 73cj5

    73cj5 Member

    Thanks for your help guys i will check it out this weekend.
     
  11. 73cj5

    73cj5 Member

    I turned out that the dimmer switch connections were rusty. thanks for your help.