Dash Lights inop

[NCali]

1987 2wd 1/2 ton 305 TBI
My dash lights do not work. I have read a thread here about troubleshooting dash lights and followed the step by step.
  When I pulled the dash out leaving it plugged in I ran the test light around each light and I have power there. no traces are broken.  I can see the bulbs lit
  I roll the dash up , install the speedometer cable plug in the clock screw the dash in place and the lights will not work
and the bulbs are all good
   Normally in order for the dash lights to come on I would have to rotate the dimmer ccw almost all the way

Thats one question:
one more question   Where is the ground behind the dash?  I have  read that it is somewhere around the e brake
but I cant find grounded wires any where around threre

[bd]

Are you referring to the technical thread: Diagnosing dash instrument lights?

The instrument cluster lamps will illuminate their brightest when the headlamp switch knob is rotated fully CCW, becoming progressively dimmer until they extinguish as the knob is rotated CW.  Is the cluster fitted with factory 194/168 bulbs or LEDs?  If the dash lamps illuminate only with the headlamp switch knob in the full CCW position, either the headlamp switch rheostat is burned, or the cluster bulbs are very low current LEDs, or the cluster ground is in poor shape.


Imaged below is a typical ground bus bar mounted to the park brake pedal frame at the left interior kick panel that is used for cabin interior and instrument cluster ground connections.



Occasionally, the bus bar is absent and the typically black factory ground wires are attached directly to the bare metal frame of the park brake pedal or the kick panel sheet metal.

Ground connections are crucial for proper electrical functions and should be disassembled and burnished to shiny bare metal.  A liberal coating of antioxidant paste is an excellent idea to help maintain good connections over the long term.

[NCali]

Bd,
Thank you for your reply. I have not found a ground connection like that and I pulled the kick panel off today
However I pulled the dash out again and found The foil damaged on the ground connection at the plug in back of the dash. I am using #168 bulbs

  my headlight switch has been getting progressively worse ofer the 20 yr s that I have had this truck

[bd]

Is the foil simply dislodged from the flexible plastic substrate or is it torn?  If the foil isn't torn, you may be able to reattach it to the substrate using some superglue and a toothpick or needle/pin.  Be careful but work fast.  Wear nitrile/latex gloves.  Otherwise, a new PC board is in order.

Regarding the dash lamp dimmer operation, it sounds like the rheostat is either dirty or wearing out.  You can try applying some DeoxIT to the rheostat wiper or simply replace the headlamp switch.  The latter is probably more cost-effective and long term.