RE: [Chrysler300] 1964 300K dash lights

["'Rich Barber' c300@xxxxxxx [Chrysler300]" <Chrysler300-noreply@xxxxxxxxxxxxxxx>]

There is a bulb located between the temperature and gasoline gauges.  It receives its power from the same pin on the printed circuit board as another bulb on the other side of the gasoline gauge.  If the second bulb lights up, the problem could either be the bulb itself or a crack between the pin and the socket for the dark bulb.

 

The dark bulb can be removed for testing as it is in a twist-out socket.  There are two types of sockets and bulbs.  One is a screw-in socket holding a threaded globe bulb. This type has two spring-wire feelers that contact copper-plated surfaces on the printed circuit board.  The other type socket holds a peanut-type bulb-rather cylindrical with a round end.  These bulbs have bare wire whiskers that contact brass surfaces within the socket and brass ears that contact the copper surfaces of the printed circuit board.  The wire whiskers on the exterior base of the peanut bulbs lok a little delicate but I have never seen one fail.

 

Both types require a good contact between the wires or ears on the exterior of the sockets as well as the contacts between the bulb and the socket.

 

Recommendations:

*	Make sure the bulb to the right of the gasoline gage is working (as you look at it from the driver’s seat).  This confirms power to the temperature socket (unless there is a crack in the ¾” of copper on the PC board (unlikely)
*	Remove and test the dark bulb and socket for continuity to the external wires or ears.  
*	Remove and test the bulb for continuity through the bulb filament.
*	Clean the internals and externals of the socket and the externals of the bulb.
*	Replace and check to see if the dark came to light.
*	If not, consider whether you want to remove the instrument panel to fix a dark bulb.  If so, 
*	Remove the ground cable on the battery.
*	Access the back of the instrument panel by rolling it out .  
*	Carefully remove the  five-wire socket from the LH circuit board.
*	Check each of the five pins to assure they are firmly attached to the PC board.  Any that are loose may be tightened by tapping the backside of the pin with a tapered punch (after removal of the PC board).
*	Check for continuity from each pin to the extremity of its copper plated circuit—especially from pin #2 (L to R) to the two bulb sockets it feeds. I clip one lead to the pin and use a pointed-end probe to contact the far ends of the trace. 
*	Remove the three bulbs and sockets from the LH PC board and polish the areas around the socket openings with Scotchbrite or some other abrasive to remove any oxidation around the openings.
*	If a crack is found, the small PC board will have to be repaired or replaced.  I’m not familiar with repairs, but soldering across a crack might work.
*	While exposed, consider replacing all eight bulbs on both PC boards and doing some inspections and polishing on the RH PC board.

 

Pictures of back of IP to Harry—available to others on request to c300@xxxxxxx <mailto:c300@xxxxxxx>          

 

Good luck-keep us posted.

 

Rich Barber

Self -quarantined and healthy in the Bay Area of CA.

 

From: Chrysler300@xxxxxxxxxxxxxxx <Chrysler300@xxxxxxxxxxxxxxx> On Behalf Of Harry Torgeson torg66@xxxxxxxxx [Chrysler300]
Sent: Tuesday, March 24, 2020 1:13 PM
To: Chrysler 300 List <Chrysler300@xxxxxxxxxxxxxxx>
Subject: [Chrysler300] 1964 300K dash lights

 

  

My mechanic said the reason my temperature gauge light dues not work because its on a circuit, all the other dash lights work. Any input appreciated.

Harry





[Non-text portions of this message have been removed]



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Posted by: "Rich Barber" <c300@xxxxxxx>
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