I have a 1990 vette, the radio started acting up, having a mind of its own, worked when it wanted. Then the digital heating and air controls started acting up, working on and off when it wanted. Both units have power and have worked on and off, but I get 3 dashes on the digitall display for the heat and a/c, the unit runs but the controls don;'t work.
ALSO: I have found a grounding screw inter the steering column on the fire wall,, but their is no wire attatched and I couldn't find a wire that would go to it..
Anybody have any thoughts? I have already pull the panels under the steering column and glove box to check the wires, i pulled the radio and heat/ ac control box out, but still cannot find my problem..
Any thoughts would be apprecaited..

you REALLY need to get a factory service manual... www.helminc.com.

But with both the radio and the climate controls wigging, I would start checking power.

The radio - be it Delco or Bose - uses a brain box (1990-1996). This box is what powers the radio head unit, and contains all the brains for the reciever.

The same thing applies for the climate control head. It is also a dummy, running with the programmer.

I would start checking all main grounding points. The dash is grounded at 2 main points, each in the kick panels, one on the left, one on the right.

Check them for corrosion.

I find it odd that both are freaking... which leads me to think something in common is wrong, and that is what the Helm manual would help you resolve.

I cleaned up 2 of my grounds under the battery tray, I was hoping that would work,, but I didn't find any grounds in the radio compartment or under the glove box.. I'll have to take that kick panel off again and try again.. Thanks for the advice..

I wonder if the ground runs over by the fuse box. I would go with what bogus said, a manual will save you time and money.

In the engine compartment on the right hand (passengers) side in front of the heater box on the top of the frame rail you should see a ground wire screwed to the frame. Check this ground it's for the blower motor among other things but can cause all kinds of issues if it's bad.

Also check the ground in front of the passengers side door below the "A" pillar. That is where the radio head unit is ultimately grounded.

The HVAC head unit grounds at the drivers side lower "A" pillar ground in front of the drivers side door. The heater/AC programmer ground could also be causing issues. This unit grounds at the same place as the HVAC head unit mentioned above.