TC-33 electrical nightmare ENDS ! HAPPILY !

[dass]

Hi all,it's been awhile.Anyway,about a year and a half ago my headlights went out.Fuse out.Replaced fuse and it was ok for a month or so and then...same thing happened.Checked wiring , grounds and harness.Everything that had an electrical connection.Found NOTHING ! But all was well until this past summer and it shows up again.NOW I've had enough.Checked all again with a meter. Readings were normal. BUT,while I was reinstalling the side cover I hit the battery cable (pos.)and I noticed it was loose inside the SEALED terminal. To shorten this story,I cut those USELESS things off of both cables and replaced them with bolt on type.....FIXED ! So don't go through this like I did, CUT them off and REPLACE'em ! ASAP

 

[RickB]

Battery cable connections fail. Odds are the bolt-on cheap fix cable ends you just installed will fail open as fast or faster than the original cable. I will not leave them on any diesel powered tractor I work on. If your tractor started every time you asked it to, I'll bet headlight fuse failure has little to do with a battery cable problem.

 

[dass]

I disagree.Any change in amps or voltage will do exactly that.Those sealed terminals are just cheaply made.You can't see through the covering to check the connection so there's no way to what condition it's in.It's what you CAN'T see that can be a pain.I'd compare them to the original ignition switch. JUNK !

 

[RickB]

You are free to disagree. My point is if the cables carry the current to spin the starter, they will easily carry the current for the headlamps. And replacement battery post cable ends will always be a band-aid.

 

[dqdave1]

I bet the price of the terminal ends were not much different than a whole new cable. My experience has been if the end is bad; whole cable is not much better.

 

[henryjacobjosh]

I have to agree with Rick.

 

[Superduper]

I'd agree with Rick too. Blown fuses are indicative of overcurrent, not bad connections. There is almost certainly an intermittent short in the light circuit. That the circuits test fine with tractor stationary doesn't mean the short is necessarily fixed. I would try wiggling the wires in the lamp circuit to see if you can "make" the short happen. Find that wire and you've found your problem.

 

[390GT]

Poor connections can cause resistance in a circuit. This in turn can reduce voltage, Ohms law states IxE=P (amps x volts = watts). If voltage goes down due to resistance amp draw has to up to compensate and fuses can blow. Greg

 

[jinman]

Ohms law states IxE=P (amps x volts = watts). If voltage goes down due to resistance amp draw has to up to compensate and fuses can blow. Greg

Okay, time for a little Ohm's Law school....

The statement that "voltage goes down due to resistance" is not true. This is also a case of using the wrong formula for this example. What goes down due to resistance is current (amps). Voltage drop in a parallel circuit like lights is the same in every leg of the circuit no matter how much the resistance of that leg changes. What changes is current. Current draw is based on resistance. Therefore if there is a bad battery connection, resistance goes up and current draw is decreased. If there is a short, resistance goes down or is zero as in a short, current draw is maximum. The correct formula to apply here is I=V/R. As resistance increases (bad connection) and voltage remains constant (battery voltage), the current will decrease.

Dirty or bad connections do not blow fuses in a DC circuit. Short circuits or something lowering the resistance is what blows fuses.

A headlamp could have an internal short circuit in the filament that caused increased current, but most likely it would flash brightly and burn up like a flashbulb. I'd look for a bare wire or other source of an intermittent short as superduper suggests.

 

[guyw]

This is a common error. The power dissipated in a given electrical circuit does not remain constant when resistance changes affect the circuit. In this case, the overall total voltage drop remains constant, the the total amps drop and therefore the total power drops. There is just added voltage dropped across the resistance, leaving less to drop across the original load.

Guy.

>Poor connections can cause resistance in a circuit. This in turn can reduce voltage, Ohms law states IxE=P (amps x volts = watts). If voltage goes down due to resistance amp draw has to up to compensate and fuses can blow. Greg