weird dash issues

[ChiFly318ti]

So I've just started having weird electrical problems with my gauge cluster and brake lights. All3 issues started at the same time.
My gas gauge will go from empty to full randomly, sometimes the needle will jump rapidly other times it will go from full to empty or empty to full a lot faster than normal. The thermostat gauge has stopped working and the brake lights do not work now.

Any ideas on where to look or where to start to diagnose this problem?

[ShortE36]

This may not seem to address the brake light problem immediately but try pulling out your gauge cluster and checking the wiring and the connections. If they're loose this might give you your cluster symptoms. As for the brake lights, I remember having all the wires disconnected from my gauge cluster and putting the key in the ignition. I didn't get that chime that you normally get when you do that. I also had the door open at the same time and didn't get the 'ding' either. It's possible it could be affecting your brake lights but that's just my guess.

One other thought - could also be a failing battery or voltage regulator! But start at the easiest stuff first.

[tiFreak]

^ the chime modules are in your cluster, that's why they didn't go off

[ATF]

I've had this EXACT problem.

I tried doubling up my rear fogs as brake lights using a relay. My solution was of course to reverse the process of adding the relay.

What I did was tap into a 12v source behind the knee bolster. I believe it went to the chime alarm thing. Also, my brake light fuse had gone out. The gas gauge and engine temp gauge would shoot up and then work, whenever I applied the brake. Have you modified any of your electrics?

[ChiFly318ti]

I will probably look at the gauge cluster tomorrow or sunday. Kinda a PITA to do maintence when you are away at school and have no covered/ heated area to work during a Chicago fall. Also, I have not done anything new to the electricals on purpose. I did notice when I was hooking up my new head unit I ran a power source to the orange illumination wire. Now my cluster and center console are always lit. The problem started before I had done that though.

[ChiFly318ti]

Alright, so I've been doing some taking apart of things, research etc. What I think it has all come down to is several part failures all in the same general time frame. I believe my fuel sending unit is going bad (would cause the gas gauge to be sporadic), the brake sensor (part by the brake pedal with the red sleeve, it is a 4 post if anyone is reading and has a good one; would cause the brake light failure).

Then I am not sure what part this would be, but a part that sends the temperature reading to the gauge in the cluster. I am fairly sure that it is not the thermostat, because the car warms up (heater blows warm air) and does not overheat.
Any info, suggestions, advice would be much appreciated.