Speedo Circuit Board help

[Wolfdog59]

Pulling my hair out a bit on this one. Have a 73 IH scout and having issues with the speedo gauges lighting. Can get the L/R turn signals to illuminate but nothing from the overall lights, high beam indicator. Brake light indicator comes on when interior lights are turned on. Also, I tested the pins and can only get the turn signal lights to work.
Are these screws providing ground? Are all of the 6 wires (44,44A,57B,56B,62G and 52A providing power or do some wires provide ground (brake light?)?

 

[Scoutboy74]

The stamped steel nuts are a conduit for the ground and can be a poor one at times. You can clearly see how the traces in the board that align with the nut locations form the ground side of most of the bulbs, with the opposite traces being the respective power sources of each bulb. The front axle warning light (4x4 engaged) is one rare example that receives its momentary ground to complete the circuit via the position of the shift lever instead. One thing you can do is make sure those nuts are torqued to the very specific value of Gutentite. Some have found it beneficial to replace those nuts with more substantial versions. If you feel the need to clean your PCB trace contacts, use a pencil eraser, but nothing more abrasive than that. Another problem that often develops with these boards is the swaged pin contacts are very fragile. One must be very careful when removing the gang plug. If any of those pins have the wobbling weeble syndrome, they're not going to conduct lightening bolts properly.

 

[ihpartsjeff]

One other tidbit, when testing any of the lights or function of the gauge, make sure it is properly grounded to the body/vehicle otherwise it will not work properly. Normally we use a jumper wire with alligator clip ends when testing gauges that clips onto the gauge and the dash, Otherwise the gauge must be installed with at least one screw tight for the gauge to have a proper ground.

 

[Greg R]

speedo gauges lighting.

nothing from the overall lights, high beam indicator.

I have similar problems with my 1210. I found the twist lock bulb holders have dirty or faulty contacts where they touch the board trace. I've gotten new ones at Napa which helped a lot for the dash lights and high beam indicator. They go in the holes with the rectangle cut outs.