Two wires from my negative battery terminal

I have two wires running from my negative battery terminal. One is the heavy four gauge one. The other is a small one that runs about three inches right to the frame next to the battery.

I'm worried about it since it is not connected well. The battery is a bit short and doesn't lock well into the battery tray (just bought the truck and it was already like this). It slides around a bit and the short, small gauge wire got ripped off.

Since buying the truck, I've had the check engine light come on twice. After the first time, it was because I had blown a fuse that was for the OBD sensor. Coincidentally(?) the small wire was disconnected. I reconnected it and a day or so later the light came on again. The battery had slid and disconnected the smaller wire again. I don't know if they are related.

Can someone shed some light on my battery wire issue? Is this second, smaller wire from the negative battery terminal important (not talking about the main negative wire)? Could it be the cause of my check engine light.

 

Yup.

 

That wire is important. Body ground
You need to make sure that one is connected well .

 

I can't get the code read since the fuse is out for that (and the cigarette lighter are altogether). Once I replace the fuse, the Check Engine light goes away.

Wouldn't the body ground be a redundant ground? Since the main, heavy gauge wire goes to the engine block which is the ground as well?

 

The heavy wire goes to the engine and is ground for the starter. The smaller wire attaches to the body and is a shield ground. While the engine has many connections to the body they are not necessarily a tight connection. The small wire ensures a good connection. There may be other ground straps attached between the engine and body as well but the one at the battery is the more important one.

 

The latest Check Engine light was for this issue. Once I made a makeshift riser for my battery so that it would tighten down securely, I refastened the shield ground (the one that is about 3 inches from the negative terminal to the body) and the Check Engine light went off.

Thank you.

 

The ground connections on the battery, frame and engine are just as important as the power connections. I would clean them to bear metal. Proper wire size is also important to prevent excessive voltage loss or overheating.

 

Yeah...actually, if that 'ground' wire comes off.....or is disconnected, you won't be able to start the truck. Been there done that on a previous vehicle....

 

The previous owner was an idiot (as far as the truck is concerned).

You need to get the right size battery in there, and make sure
the hold-down works properly. If that is missing, get one
from a wrecker. Then connect that ground wire.
Missing grounds can cause all kinds of problems.

 

O hai guise?

I think the OP resolved this back in November of 2011. Not sure if he will see your suggestions...But still nice of you to help out.

 

Replace the ground wire and re ground it. Bolt the battery down.

Edit. Damn......