Re: Possible culprits behind intermittent headlight loss?

Ashton Crusher wrote:
> On Wed, 20 Jun 2007 10:10:46 -0400, Mike Romain <romainm@[EMAIL PROTECTED]
>
> wrote:
> 
>> Doc wrote:
>>> Have a '66 Fairlane wagon, the headlights will blank out after maybe
>>> 15 - 20 minutes on low beam. Turning the switch off for a few secs and
>>> then turning on will typically get them back on tem****arily but
>>> they'll continue to go out. Further, hitting the hi beams is almost
>>> guaranteed to kill the lights. Replaced the switch and the floor
>>> dimmer, neither cures the problem.
>>>
>>> Any suggestions as to where to begin looking?
>>>
>>> Thanks.
>>>
>> I see that happen to old vehicle when folks try to run halogen bulbs in

>> them without adding a power relay.
>>
>> The bimetal circuit breakers in the old switches cannot take the amp 
>> draw the modern halogen bulbs draw.
>>
>> The old time conversion kits that were sold when halogens first came
out 
>> are a simple Bosch relay that is fused to the battery and wired so the 
>> switch is just the trigger for the relay.
>>
> 
> There is almost no difference in the current draw between the old
> bulbs and halogen.  

There is enough difference to blow the bimetal circuit breaker, 
especially when the high beams kick in.  There is a 'reason' we needed 
the conversion kits, every one I have seen without it has sooner than 
later cooked the switch.

Some kits (one for my 1970 Pontiac Safari Wagon) even wired the relay in 
parallel with the light switch circuit so the headlights got two power 
sources which was enough to keep that bimetal switch cool.

> 
>> Here is a site on how to wire one in.
>>
http://www.classictruckshop.com/clubs/earlyburbs/projects/bosch/relay.htm
>>
>> The other reason I see the breaker cook is a bad connection in the plug

>> for the headlight switch.  The main power wire's spade connector can
get 
>> ratty which will cause arcs and heat and breaker failure.
>>
>> I see this same bad connection on the floor dimmer switch plugs.
>>
>> And last, a bad ground can cause heat issues.  I would verify the 
>> headlight ground tags and the body's main ground from the battery.
>>
>> Mike
>> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
>> 88 Cherokee 235 BFG AT's - Gone to the rust pile...
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