I need help, no idea where to start on this one.

My Civic Wagon 1990 has been standing idle for 7 months (moist climate), and now that I am driving it again, the electrical stuff acts weird. For example, when I use indicator, the RPM gauge start to rapidly back and forth, while the temperature gauge runs up to way to hot. Same issue with bright lights (RPM gauge to zero, temp gauge to boil). This does not always happen, but more often in the morning. I suspect moisture is making a short. But where and how do I fix this issue?

I also found a draw linked to fuse 34 (red 10 amp fuse under the hood), which goes to the ECU. Fixed that one by putting some WD40 on the ECU connector linked to fuse #34.

 

Try disconnecting everything that connects to the fuse box. I messed up once connecting mines and the wiring was all funky

 

Try cleaning your battery terminals with a wire brush, also the battery posts. Ive seen similar behavior from just a loose terminal.

 

CLEAN ALL 3 BATTERY TERMINALS AND ALL GROUND WIRES WITH SANDPAPER AND ALL CHASSIS GROUNDING POINTS WITH SANDPAPER.

 

I would first give my attention to the thermostat housing ground, (because its close from the distributor(RPM) and water temp sensor)
and than check all the others ground like crazyhouse says

 

I sanded the thermostat housing ground, the ground that come directly from the battery (new battery BTW), and the ground between the engine head and the chassis. Behavior remains.....

 

And the answer is hopefully found. Today I had enough , and I decided to really get to the bottom of it. I had dug up the circuit diagram of the car, and all the instruments with weird behavior had one thing in common, the ground. So, I took the gauge assembly out, and then I tested whether

1. the ground from within the connector to the frame of the car had continuity: Perfect
2. the ground on the printed circuit had continuity: Perfect

So, I started to wonder what it could be. I took the gauge assembly inside, and I noticed the following:




The printed circuit.



The most left connector on the printed circuit, which corresponds with the ground, was messed up compared to the others, and I had never taken it out or anything like that. So, why was it like that. When I looked under the printed circuit, I saw this:




Under the printed circuit.



The plastic under the printed circuit had been melted and had resulted in some additional space in the connector, and I suspect that this was the reason for the weird behavior that I have experienced.

So, what I have done is put a few small layers of duct tape on the depression, till it was flush again, and then I reassembled the car. The weird behavior is for the moment gone, but that happened before, so I have to wait and see what it does when I drive it a bit more......

 

The melted plastic suggests that a hot wire shorted to ground. This is the root of the original problem that should be fixed.

 

it was the ground connector that melted? your's still has a speedometer cable right? if you have a bad engine to body ground, then everything on the engine will try to ground through the speedometer cable and the throttle cable, and through the small ground wires in the cluster, this used to happen all the time before they went to an electronic speedometer with a VSS, you don't hear about it much anymore, as it only happened on the older cars. It used to be common to have a speedo cable or throttle cable actually melt when a ground came off, be glad your issues aren't related to a mouse getting in there while it sat

 

here's an example for you, pulled it up just by searching for speedometer cable melted Honda, if it was a short, at least there is a fuse to blow, but if everything on the engine is trying to ground through the cable, there is nothing to limit current, and you end up with a mess https://honda-tech.com/acura-integra...-like-2289594/

 

Yeah, I think I know the root cause (some no-start and ground issues at the beginning of this year), and that was fixed several months ago.