Some of you may know that the dash light in B series
trucks are known to fail. Both my father and I own
B2200 and have had problems with the dash lights not
working. I have found that usually the problem comes
from the dimmer switch in the dash.
To test to see if your dimmer switch is bad all you
have to do is short terminals B and C on the dimmer
switch socket. To get to the socket you will first
have to remove the 4 screws holding in the speedometer
cover. Once you have the cover removed just unplug the
socket from the back of the dimmer switch. If your
looking at the socket as shown below, just take a wire
and short out the two terminals in the socket that are
facing the same direction, terminals B and C, and turn
on your headlights. If your dash lights light up your
dimmer switch is bad, if not there is a problem
somewhere else in your dash electrical system.
Warning: Do not let either terminal B or C short with
terminal A this will blow the fuse.
Note: The dash lights are hard to see during the day
and I suggest performing the test at night or in a dark
garage. Wire shorting terminals B and C shown in blue.
As long as C and B are shorted going into the plug
your dash lights will show at full brightness. So
you have multiple ways you can short out the two
pins. If your happy with just keeping the switch unplugged just make a jumper out of two spade connectors and put some heat shrink over them, then insert the jumper wire into the plug like shown above and your done. I didn't like the idea of the plug flopping around in there with wires hanging out of it so what I did is disassembled the switch and
and soldered a piece of 5A Fuse across where the
two pins solder to the switch board. (The arrow Below)
To open the casing you must take a small flat head screw
driver and get under the top of the case and pry out. It's
a little tricky the first time you do it.
Being since the switch is essentially useless now the
simpler way is just to leave it unplugged and run a
jumper from pins B to C in the socket and leave the
switch in the dash just for looks.