Can't Start '08 Civic (Diagnosis)

Question

I bought an '08 Honda Civic LX (110k miles). After a few days of flawless driving, I noticed a couple wires NOT connected that were coming from the hood opener-sensor thing. I plugged them together and noticed no difference in the car until I let the car sit for about 6 hours. That's when the trouble started.

I tried starting the car. The engine had trouble cranking and then would stop. I pulled the key out and tried a couple more times. Finally, the engine started.

The next day, I had to do the same thing to get the car to start.

Now, 2 days later, the car won't even crank. No ticking, no cranking, nothing. When I turn the car to "On", everything works (stereo, lights, headlights, dashboard lights- everything). You would notice no difference until you tried starting the car.

The battery date is 10/14 so it's coming up on 2 years old. I haven't tried cleaning the battery connections yet. Just looking at them, I cannot notice any problems or visual corrosion.

I'm thinking that because I plugged those wires from the hood-sensor-thing together, it's a bad sensor which drew current from the battery while the car was off. If this was the case then jumping the car would probably fix it, but nope, not my lucky day. Jumping the car didn't help at all.

Before I start checking fuses and connections, I would like any insight people have on what the problem could be.

Answer 1

So, the most likely explanation with things like this – at least in my experience – is that those wires were disconnected for a reason. It's very likely that you know the reason now…

What this sounds like to me is that there is a load associated with the hood sensor/opener that drains the battery and all of the other symptoms are related to that.

So:

1. Disconnect the wires and see if the problem goes away. If it does you've pretty well identified the source of the problem – or at the very least the system involved with the problem.

2. If the problem does go away, then the next step is to figure out where the problem is. Without knowing much about the "opener/sensor thing" I'm wondering if it has a motor or solenoid in it that might be stuck or if the circuit that controls it might be trying to release the hood all of the time.

3. So, if you can find a schematic for the circuit, take a look at it and identify the components involved. I would expect (without looking at the circuit) that there should be no voltage measure across the circuit when the car is off. It could be switched on either the hot side or the ground side, so you might see a voltage between one wire and ground, but I would expect nothing between the two wires (assuming that it is a hood release actuator).

   If it is part of the alarm system then you may see a voltage there. In that case it would be worth measuring the continuity (resistance) between the pins of the "opener/sensor thing" to see if the sensor is stuck in the closed position. That might have been continuously triggering an alarm or there might be enough of a draw on it that it is able to pull the battery down.

4. Once you get an idea of what is happening they you can decide if it is worth digging into further. As you learn more, please update your question. That will increase the chance of getting a fix and will also help others with similar problems.

Answer 2

Look at each fuse in the fuse block,test each of them for continuity using a meter. I am suspecting huge loads after you connected those wires.