E30 fuel gauge warning lamp illuminated but is full, sending unit or ground nut?

[formyhealth]

Hey so I noticed before I changed my fuel pump that my gas gauge on a 1991 318is was acting erratic, the low fuel warning light is on regardless of tank level and the gauge register anywhere from empty, to half to full. Is this a fuel sending unit issue or a grounding nut issue on the cluster? Maybe a cluster issue not relating to the ground nut? Also the temp sensor is also erratic but I noticed if I give the dash above the cluster a sharp whack that the temp gauge acts normal for a minute or two (doesn't do anything for the fuel gauge though)

Here's a picture:

[roguetoaster]

I've not seen the fuel light come on when there is a bad ground, but the temp gauge being erratic is often a sign that the ground needs to be resecured. Therefore, I'd start there and if the low light is still on you can unplug your level sensor to further diagnose the issue.

[formyhealth]

I've not seen the fuel light come on when there is a bad ground, but the temp gauge being erratic is often a sign that the ground needs to be resecured. Therefore, I'd start there and if the low light is still on you can unplug your level sensor to further diagnose the issue.

Thank you for the advice, I'll pop the cluster out and tighten down both ground nuts and see where that takes me.

Danny