car shuts off with hi beams on

[joe fremeau]

Hi,Weird electrical problem,my car will shut off when the headlight switch is put on and will not restart with out a battery charge, also the directional will not works with the lights on,the battery is new.Could it be a ground problem? thanks

[Toptech360]

Is your alternator functioning? Does it happen witg high beams only or low beams also?

[joe fremeau]

The alternator is new and it happens on high beams

[fj20spl311]

Bad Battery is my first guess.

A bad connect at the battery is another possible reason.

Once you get her started and turn on the high beams and the engine dies have you checked the voltage at the battery?

It would have be a combination of problems to recreate your scenario.

If the alternator is charging then turning the lights on should not lover the voltage enough to kill the engine.
A fully charged battery should be able to support the ign. and the lights for quite some time even without the charging system working.

[jrusso07]

First do as Phil suggests. Read the battery terminal voltage before and after applying the high beam switch.

If not the battery, perhaps something mechanical is happening in the ignition switch or the high beam circuit is miswired and is somehow cutting the run voltage to the coil?

Also try disconnecting the headlight relay to isolate the problem to the switch side

[rexj2003]

Did anyone get the fix to this headlight problem?? I have the same issue on my 69 2000. I had major light problems,,mostly grounds and broken wires rotted pigtails etc. I also found it odd someone had joined the 2 headlight circuits at the fusebox,,if I unhooked the scotchlock,,,they didn't work I even swapped fuse box and had to jump the 2 circuits together to get them to work,,now all lights work well,,but now and then when running and I switch the hi beams on,,it kills engine,,,only the horn works,,and after abt 30 minutes the car will restart. and seems fine.I have 5 of the roadsters,,so I may swap relays,,ignition switch,,and volt regulator,,,,any ideas??

[redroadster]

yeah a complete electrical tests are a good start
amps output test mostly , can you turn on about everything else and it runs ok ? whats it do with the lamps unplugged ?

[rexj2003]

I can try an amp test,,,tho I don't have the test equipment. When it is running everything is fine and sometimes you can flip the high beams on and off with no problem but when it does happen to kill the engine its as soon as you flip them on. I can try with the headlamps unplugged, tho I wont know much cause its so intermittent. the amp meter on dash shows movement as you rev it,,and neg if you turn on lights with car off.

[C.Costine]

Did anyone get the fix to this headlight problem?? I have the same issue on my 69 2000. I had major light problems,,mostly grounds and broken wires rotted pigtails etc. I also found it odd someone had joined the 2 headlight circuits at the fusebox,,if I unhooked the scotchlock,,,they didn't work I even swapped fuse box and had to jump the 2 circuits together to get them to work,,now all lights work well,,but now and then when running and I switch the hi beams on,,it kills engine,,,only the horn works,,and after abt 30 minutes the car will restart. and seems fine.I have 5 of the roadsters,,so I may swap relays,,ignition switch,,and volt regulator,,,,any ideas??

I think that I would be tracing the wire that dead-ends due to the two light circuits being connected with the scotch lock at the fuse block.

[Linda]

What is a scotch lock???

Linda

[greydog]

They're the little plastic wire taps. It holds two wires, there a sort of staple in the center and a cover.
You put your two wires, one in each indentation and close the cover (other plastic half) causing the staple to bite through the insulation and make connection.
Works ok most of the time but imho should only be used in an emergency.
Dan

[dbrick]

Did anyone get the fix to this headlight problem?? I have the same issue on my 69 2000. I had major light problems,,mostly grounds and broken wires rotted pigtails etc. I also found it odd someone had joined the 2 headlight circuits at the fusebox,,if I unhooked the scotchlock,,,they didn't work I even swapped fuse box and had to jump the 2 circuits together to get them to work,,now all lights work well,,but now and then when running and I switch the hi beams on,,it kills engine,,,only the horn works,,and after abt 30 minutes the car will restart. and seems fine.I have 5 of the roadsters,,so I may swap relays,,ignition switch,,and volt regulator,,,,any ideas??

If you have a double row fuse box, the headlights get + voltage from one fuse per headlight all the time to the common terminal of the headlight and the headlight relay provides - voltage to either high or low to turn the filament on. If this gets crossed into a normal circuit, where ground is common and + voltage switched, it can get very weird. Look at the wire diagram and it will make sense.

[rexj2003]

Thanks for all the input,,,,I ran the car yesterday for abt 15 minutes all good which is common. I did clean main ground strap from battery,,had some paint from my engine rebuild this summer. I guess I should remove that scotch lock from 2 headlamp circuits and see what I have then. Its odd that the entire harness is intact BUT someone had the 2 h/lamp circuits together AND a wire from the left h/l to somewhere under the dash at 1st I thought it went to fuse box,,but I think its wired into a main connector by firewall and pedals,,its not spliced in,,but is plugged into that connector like a factory job or a very good repair,,ive unhooked that new wire from headlamp and it doesn't work. also 1 other detail the 3 headlamp wires are hot all the time is that normal?? seems odd too. One of my best friends now living in NC is a master tech and has gone to national competions for wiring problems,,,and usually finishes 2nd or 3rd,,,but he cant diagnose over texts. backto the schematic ,,I wonder if the left h/lamp wires are not correct? flip flopped maybe?

[dbrick]

You could pick up one of the Victoria British headlamp relay harnesses and just use the factory wire from the headlight relay as a trip. Disconnect what's not used until you can fix it. Crazy wiring repairs scare me, they too often result in fires/meltdowns.