Prostar Alternator wire?

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by artycbear, Feb 21, 2020.

  1. artycbear

    artycbear Bobtail Member

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    Feb 14, 2020
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    On a 2009 Prostar Premium, I have replaced the Delco Remy alternator with a Bosch. The D/R had one hot wire, a ground wire and a third wire attached to the post marked Sensor. There were 2 more posts on the D/R alternator labeled R and I, which were unused. The new Bosch alternator has post for 2 Hot battery leads (i used one) a Ground wire bolt, and two other posts, one for the tach gauge and one for the alternator light. I have no idea which of these two posts to run my third wire to. I left it unattached (the third mystery wire) to see what wasn't working without wire hooked up. The tachometer worked as well as the voltage gauge, so i'm not sure which post to put the third wire on. Any help would be appreciated, thank you.
     
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  3. pushbroom

    pushbroom Road Train Member

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    Medium & Heavy Duty Alternators | Delco Remy

    That probably has the best explanation on the remote sense wire. Quick and dirty is the remote sense wire gives the alt a voltage read off the batteries without having voltage drop from dirty battery cables.
    If the new alt doesn't have a spot for it just heatshrink up the terminal so it cant spark out on something as it will be hot (+12V). More ideally would be to remove the wire completely, no idea if its factory or added on after the fact.
     
  4. Heavyd

    Heavyd Road Train Member

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    Yes. Just what Pushbroom said. It's the remote sense wire. Cover it up and tie it away. Ok to run without. It will be factory and should be a 5 amp fuse for it at the batteries if you want to disconnect it.
     
  5. artycbear

    artycbear Bobtail Member

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    Feb 14, 2020
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    Thank you for your input, appreciated highly.
    i called the guy with the prostar and told him we could leave that wire (capped off and tied down) or take it off, he decided to just leave it where it is.
    Again, Thank You.
    Cheers.
     
  6. Lockport

    Lockport Light Load Member

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    Mar 26, 2011
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    The remote sense wire is very important if your are running AGM batteries as they will prevent overcharging. For example I have 4 AGM Deep cycle 990 CCA batteries that were near $1,000 and I put a new (rebuilt) Wilson 36SI. The remote sense cable grounded out at install and blew the 5A fuse. This was obvious as the charge current was somewhere around 50A and the voltage read was 15V. This would destroy those batteries fairly quickly. Upon immediate replacement of the Remote Sense 5A fuse the voltage returned to 13.5 with a charging amperage of less than 10A. When the truck is initially started it will draw significant voltage and the alternator will immediately put out 50A+ but this will scale back very fast and is just a high current flow to replenish the voltage draw. I would consult Bosch for clarification on which terminal that wire should attach to and connect it.
     
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