Electrical Problem

   / Electrical Problem #1  

DFW

Bronze Member
Joined
Feb 25, 2004
Messages
95
Location
Red Bluff, California
Tractor
Task Master 432E
It seems whenever I turn on any of my lights (headlights, marker lights, working lights, signals) and the tractor is running, my tachometer stops. Also, with the tractor not running, if I switch the lights on the ammeter jumps to the positive side. Any help of where to start looking would be much appreciated. FYI, the ammeter never goes negative... /forums/images/graemlins/confused.gif
 
   / Electrical Problem #3  
1st guess is that something(s) wired in parallel are not in the proper polarity. It's all DC. Pluses go to pluses and minuses go to...uh...minuses.

-OF
 
   / Electrical Problem
  • Thread Starter
#4  
I haven't done any wiring, unfortunately I think it came this way...
 
   / Electrical Problem #5  
Sounds to me as if the lights have been wired into the ammeter/tach circuit thereby draining the power away from the tach when running and producing current flow through the ammeter when not. I would check the location of the hookup and if it's hooked to one of the ammeters posts you can either try moving it to the other post or run a wire directly from the battery thru a fuse then to the lights.
 
   / Electrical Problem #6  
I had a Corvette that showed a constant 40 amp charge for over a year. When I finally got around to fixing it I found a bad connection near the place where the ammeter connected into the charging circuit. I would look for bad connections (opens) on the tractor. Be careful because the ammeter has a shunt ( a very low value resistor; i.e., a wire ) across it. If you accidentally or purposefully remove the shunt you will burn out the ammeter instantaneously.
 
   / Electrical Problem #7  
Check for poor grounds,such as loose hood bolts, loose dash, ect. thats usually the problem when you turn one thing on and it causes something else to go haywire.
Wayne
 
   / Electrical Problem #8  
Ok here is what I would check first:

you say the amp meter ALWAYS shows a + charge? this should not be the case when cranking or turning on the lights when the engine is not running at all. if it is then the ampmeter is wired backwards. the wires need to be reversed from one side to the other, simple fix there.

now when you turn on the lights the tach quits. this could be a few things, unfortuenatly troubleshooting electrical stuff over the NET is one thing the net is lacking in. I would first think that like others said power is being drawn away from the TACH hot side. easy check is to start with tach on and a ohmmeter set to 20 DC volts, check the + lead into the tach + post on back of it. and use the meter black to the ground post on the battery, and then to the ground wire at the back of the tach. the voltage should be somewhere about 13.5~14 volts with the engine at 1000 rpm or so. by moving the - side of the meter form the - battery post to the ground post of the tach you will see if there is any faulse resistance build up in the ground. then do same test with the lights ON. the voltage will drop a little but still should be at least 13.5 volts to the battery - side.

NOTE: be sure to NOT cross the tach sensor trigger wires!

now next step. check the ground voltage from the - wire on the gauge grounding point to the - lead post on the battery. there should be 0 volts or less than .5 on a digital ohm meter... If there is a voltage then clean the battery ground cable to tractor frame of rust paint ect... and start over.

DO NOT TRY TO CHECK THE VOLTAGE LEVEL ON THE TACH PULSE GENERATOR WITH a STANDARD METER! you may burn it out. make sure that the meter input resistance is greater than 1 megohm and if so then you can try and test it. otherwise follow the MFG suggested testing procedure.

set meter to DC voltage and check for voltage across the two leads out of the sensor (mag pick up type) and then set to AC and test again. you should see a little DC which raises the sensor above ground slightly but the main componet is an ac pulse which most digital ohm meters may not be able to see as it is only on for a small time then off for a larger time, in this case you need a analog meter or an OSCOPE. if you get some readings mark them down and do test over with lights on. the lights may be putting enough juice into the tractor frame to push the tach refernaces off scale and the tach drops off..
if the first test was ok (with the + on the tach staying fine with lights on.) if so then best way to fix is to run a ground wire from the lights ground post (usually the mounting post too)back to the - post of the battery. and a new + wire from the battery startor solnoid through a fuse to the switch and on to the lights + side.

ok please post back with the results of the testing prodedure you did. and if it is solved or not... be sure to right down all meter readings both lights on and off and let us know.. itr will help narrow down possable causes later i f it is not fixed and help others if it IS fixed. /forums/images/graemlins/smile.gif

Mark M
 
   / Electrical Problem #9  
Good going spiker!!! usually most problems are bad grounds/ terminal connections/ connections /forums/images/graemlins/laugh.gif
 
   / Electrical Problem #10  
Clean the battery terminal and make sure that the battery negative ground terminal is making a good ground on the engine block or where ever it is bolted to. Many times a poor ground will cause current to flow in a direction that it isn't normally intended to because it is seeking a path to ground. I remember having a car that the radio would start to play even though it was turned off when you would step on the brakes. Fixed all the grounds and the problem went away. For some strange reason, that was the path that the stop lights were taking back through the radio circuit to ground. I never did understand it, but the auto electrical shop that I discussed the problem with knew right away what the problem was. That was with a 1960's car, but the tractor might have the same simple wiring.
 
 
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