Query - Chasing EF Civic Electrical Gremlins

I need some help in tracking down and eliminating an electrical problem.

The car is a '90 Civic Dx that's still on most of it's OE electrics. Last driven this weekend, it started and ran just fine but today it is completely dead; not a single sign of life.

What are the most likely points to track a bad ground or constant draw on an EF? For the record, I have the FSM and as the only owner, I know the car's history better than most.

Also, what's recommended as a good, reliable diagnostic tool?

I've always been able to borrow in the past but it's time to add to the personal inventory and get on with keeping this old stuff running as well as possible. I've never been on top of the electrical end of things, but now is as good a time as any.

Check the main relay under the dash first.

When my main relay in the EG failed I don't remember it acting quite the same way - I don't recall it being "dead-dead" with no warning lights or anything, I just remember the fuel pump would not engage and it would just keep turning over.

The main relay is such an easy fix though it wouldn't hurt to check it out. I just resoldered all the connections on mine and it was right as rain.

The main relay won't make the car dead, it will only make it not start. If you have no power at all, you need to start at the battery.

bravenrace wrote: The main relay won't make the car dead, it will only make it not start. If you have no power at all, you need to start at the battery.

The battery is six months old; not saying it isn't the problem, but it's not the likely cause.

Anyone with experience on the most likely grounds or other EF areas that are sources for a constant drain on a battery?

In reply to oldsaw:

What I meant is start at the battery and work from there, not necessarily that the battery itself is bad. But you should verify the battery and alternator are good first, then the cables between them, then check for a draw. I've owned many of these cars, but unfortunately have never had one with a draw, so I can't help you with that. If you do have a draw, I'd probably start pulling fuses until it stops, then check everything covered by that fuse.

bravenrace wrote: In reply to oldsaw: What I meant is start at the battery and work from there, not necessarily that the battery itself is bad. But you should verify the battery and alternator are good first, then the cables between them, then check for a draw. I've owned many of these cars, but unfortunately have never had one with a draw, so I can't help you with that. If you do have a draw, I'd probably start pulling fuses until it stops, then check everything covered by that fuse.

Get yourself some electrical diagrams. Most of the EF shop manuals are online. Google for it. Those manuals also have troubleshooting charts that should help.

Sounds like either something in the main fuse box (e.g. ECU fuse) in the engine bay or the ignition switch. A single bad ground won't do it, as there are many.

My CRX had a problem at the door-open/dome-light sensor. If the door wasn't shut just right it would drain, even without the dome light actually being turned on.

Another thing is to check is the plastic button that is in charge of depressing the clutch safety switch. It gets old and brittle and ends up in pieces on your floorboard.

not a single sign of life.

Guys, It's dead dead. Main relay, and plastic buttons while good generic EF answers, doesn't answer his specific problem.

So does dead dead meaning no juice at the battery, or have 12+V at the battery and nothing else works?

Maybe not the button on the clutch switch... But the button that depresses the brake light switch.... Button falls off, brake light stays on all night. Dead...

As was said, start at the battery and confirm there's voltage there. That means putting the meter right ON the battery terminals. At this point, EVERYTHING is suspects, especially wires and cables. If you see 13V at the battery, THEN move the meter leads to the battery clamps and see if it's still there. If so, put the negative meter lead on the chassis, and the positive right on the starter motor. Still there? Try shorting that terminal to the small starter terminal - the engine should crank. Try that and get back to us.

A 100% dead car can only be due to a dead battery (for one reason or another), or a blown main battery fuse if present.

If there power in the battery and everything else seems dead, Check to make the ignition switch is working correctly. Those will wear out in Hondas over 20+ years of use.

bravenrace wrote: In reply to oldsaw: What I meant is start at the battery and work from there, not necessarily that the battery itself is bad. But you should verify the battery and alternator are good first, then the cables between them, then check for a draw. I've owned many of these cars, but unfortunately have never had one with a draw, so I can't help you with that. If you do have a draw, I'd probably start pulling fuses until it stops, then check everything covered by that fuse.

Along with that, the battery cable connections are often the problem. corrroded, loose. Cables them selves can get corroded. check for voltage drop.

Always reminds me of a case I once had. Used car, customer drove it home. sets over night. Batttery dead in the morning. Bring it to shop, every thing checks out. Repeat three times. Finally found , car is parked on a slope. Mercury switch for underhood light needed adjusting.

In reply to iceracer:

That would be a tough one to diagnose.