Crashmaster91

I have an 92 Civic CX with a B20-V swap in it. I just finished putting the engine back in yesterday and got all the wiring hooked back up. Car started no problem and was able to drive around the neighborhood. I parked it back in the garage to do one last check before buttoning everything up. When I went to move it, it made a small click and then just lost all power. When I turn the key, the fuel pump doesn't prime, the main relay doesn't click, nothing.

I have been checking power, grounds and fuses all day today and about to lose my mind! Brand new Odyssey PC680 shows 12.4 volts at the terminals, and all fuses and grounds check out. I checked the power at the fuse box from the battery and it shows 12V also. The main relay did make a weird squeal noise at one point, but I haven't been able to repeat it. The thing that I though was weird, when I turn the key to ON(III), the voltage drops to .5V on the fuse box battery connection (don't know if that's how it's supposed to be). Any help at this point will be appreciated!

mk378

You have a bad connection somewhere. Very often it is where a battery terminal meets the battery. Clean the inside of the terminal thoroughly. Loosen the nut and push it all the way down onto the battery post. You should have some battery post showing above the top of the terminal. Then tighten the nut.

If that doesn't help, use a voltmeter to troubleshoot as follows. Turn on the key and leave it on so there is a load on the system. Measure that there is still 12 volts across the battery. If it dropped supstantially at the battery posts, the battery is run down and/or bad. Finding battery is OK, put one lead on the (+) battery post and move the other one along the circuit-- to the terminal, then to the connection at the fuse box, and both sides of the main fuses. A good connection will read near zero. If you read near 12, you have just gone past a bad connection or blown fuse. Repeat on the (-) side of the circuit, going from the battery post to the body and engine grounds.

Crashmaster91

Don't know if this helps, but I have no brake lights when I step on the pedal or headlights when I flip the ****. I have been seeing that brought up in a lot of articles, but never see what the cause of that is for power loss.

I was doing some voltage testing at the ignition switch. I get 12v from the batt connection, but as soon as I turn the key, the voltage drops to 6 volts across the batt and acc connections. On(II) gets 3 volts (IG1) and on(III) kills almost everything down to .3v (ST)

I have done this with 2 batteries now. Brand new PC680 and the previous working 51r. Both have sat on the chargers today until full just to make sure.

I'm tracing everything out again. It kills me that the car ran and drove just fine and then as soon as I go to start it again, I have nothing. ​​​​​

mk378

The headlights and brake lights are powered from the fuse box under the hood and do not go through the ignition switch. This means that the problem is under the hood. Do the tests I said to.

Crashmaster91

Thanks for all of the help, I figured out the issue. I followed your instructions all the way down the positive and everything checked out. I went through the grounds and all seemed fine, but the ground from the battery to the chassis was the problem. It checked fine across the multimeter, but when I set up another cable and found a different spot, everything started working! Thought it was weird that the ground that worked previously just stopped working.