ok, first of all i will start with how the circuitry works and how you can fallow this maze ...simple. everywhere that you see the brown squiggles in the sheet attached to the back of the cluster? imagine those as just regular wire. notice how you can fallow from where the plug goes into to all over the board? this is why i have sharpie all over it so i could trace were voltage was going.
next is how do each individual gauges work? simple, and with how they work is how you can put in any gauges you want!!! so you see how if you where to take the cluster apart there are 4 main gauges tach, temp, speed, fuel. all of these gauges are bolted in with 3 screws (except speedo which is 4 screws). These screws are key to your gauges working! notice how there is copper where the screw goes into. those are power supply, ground, and signal. at the very bottom of the cluster where there are two bolts far appart are for the clock power and ground.
with this being said how do i figure out what these abbreviations are? lets start.
chg- charging system, notice how ign powers the bulb and then after the bulb goes back to the harness to make the dummy light work ( otherwise the dummy light would be on all the time)
door- pretty simple, notice how ign also goes to bulb and then underneath there is a soldered jumper and then goes to harness to make it work. this is simple because if there is a door open all its doing is grounding that bulb. if light doesnt go out replace door sensors.
gnd- this is the gound circuit for everything and there are multiple points where it says gnd main thing to check for here is if there is 12v on the ground wire. big nono.
tm- temp signal for gauge. if temp gauge has power and ground and still doesnt work then take a jumper wire and ground out the "tm". if the gauge maxes out then the gauge does work
ign- the most important, 12v with key on. also probably the most common problem
brk- there are two brk's one for brake and one for seatbelt, again, ign powers the bulb and works by going back to the harness
batt- 12v constant power to the clock
beam, t/r, t/l, gnd and the other beam are all part of the blinkers and highbeams. only problem i ever see with these are bulbs. i will explain further at request
tam- tach signal input from ecu.
ill+ illumination for gauge cluster lights.
fuel- is the fuel gauge ground
fm- is the signal from sending unit in the tank, ground fm and the gauge should max out.