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7120 low voltage on dash


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The 7120 I spray with shows low or no voltage on the bar graph, low enough that the systems monitor green lite goes out. I have replaced the cab stud in right corner of cab and have around 14 volts there. Lights are bright and everything else works great. Does anyone have a wiring schematic for the dash from the lower right cab corner?

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Is it charging? There is a wire that takes 12 volt to the alternator to excite it if I remember correctly on those

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1 hour ago, bitty said:

Is it charging? There is a wire that takes 12 volt to the alternator to excite it if I remember correctly on those

I pulled dash out and found a mouse nest and a couple chewed up wires. Patched them and now it shows 6 bars. Before it would be 0 to 2 bars. Running with no accessories on it shows 13.9 at cab stud. AC, radio, outback S2, raven 450, and Sirius radio on, the voltage drops to about 13.1. I'm going to run it today and see what it does, just didnt want the systems monitor to not work. May be time for an alternator, sure this could be original at 11500 hrs.

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3 hours ago, Little Red said:

If you have 13 to 14 volts at cab stud then I would say your alternator is working fine, I would check grounds before replacing alternator 

Ran it for a few hours yesterday, did read 4 bars on dash for voltage. With everything powered up it gets down to about 13.1 volts. I'm guessing problem was bare wire or connection at back of dash, seems to be working as good as it ever did

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I have been threw this on my 7120.  It nearly drove me nuts.  I carried a meter in the cab for a year.  No matter what that bar graph said the alternator was always working.  A couple years later one night the alternator did fail.  Of course the gauge was no help.  Anyway, when I replaced the alternator it fixed my problem.  Not sure what it was.  A connection on the alternator maybe.  I don’t know.  When I got rid of the 7120 it was still working ok.

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Stop at your local shop that rebuilds alternators and pickup a brush /regular assemble , it’s a 5 min job to change it out . Just on the back side of the alternator remove the plastic cover and two screws and the assembly pulls out , slip the new one in and and your good to go . Those Bosch alternators are really good units and this is about all that ever happens to them .

‘Danny

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Can the replacement of that same assembly correct over charging?I have on the other hand a 7210 that maxes out the bar chart and alarm after start up and I have to turn on field lights to bring it down to operating range. 

 

Will I be helped by changing the assembly mentioned in the previous post?

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Yes Mark , I think if you get the regulator from a Bosh dealer if you can find one close to you or Oder it . They are way better quality than the ones you get from the rebuild shops .

‘Danny 

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