voltage gauge oddity
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Junior User
Joined: Nov 2004
Posts: 95
Likes: 0
From: Kalispell, MT
voltage gauge oddity
I posted this in the electrical forum but have no respone yet so I am trying here too.
<TABLE width="100%" border=0 itxtvisited="1"><TBODY itxtvisited="1"><TR itxtvisited="1"><TD vAlign=top itxtvisited="1">I have a 97 f-350 crew 4x4. It has two batteries and I just recently got it. I don't know if this is normal or not but when I turn the ignition on the needle is just above n on the word normal on the gauge. When the wait to start light goes off I hear a click and the needle goes to the left and below the N. I thought it was the batteries so I replaced them and cleaned the terminals. It is still doing it. My dads 99 f-350 diesel initially registers lower on voltage and then when the glow plugs turn off the needle jumps to the right.
When the truck is running for a minute the needle goes to m on normal but not right away after starting.
should I worry or not it seems odd
jeff
</TD></TR></TBODY></TABLE>
<TABLE width="100%" border=0 itxtvisited="1"><TBODY itxtvisited="1"><TR itxtvisited="1"><TD vAlign=top itxtvisited="1">I have a 97 f-350 crew 4x4. It has two batteries and I just recently got it. I don't know if this is normal or not but when I turn the ignition on the needle is just above n on the word normal on the gauge. When the wait to start light goes off I hear a click and the needle goes to the left and below the N. I thought it was the batteries so I replaced them and cleaned the terminals. It is still doing it. My dads 99 f-350 diesel initially registers lower on voltage and then when the glow plugs turn off the needle jumps to the right.
When the truck is running for a minute the needle goes to m on normal but not right away after starting.
should I worry or not it seems odd
jeff
</TD></TR></TBODY></TABLE>
Post Fiend
Joined: Apr 2004
Posts: 12,835
Likes: 3
From: Silver Lake Dunes, MI
I posted this in the electrical forum but have no respone yet so I am trying here too.
<table itxtvisited="1" border="0" width="100%"><tbody itxtvisited="1"><tr itxtvisited="1"><td itxtvisited="1" valign="top">I have a 97 f-350 crew 4x4. It has two batteries and I just recently got it. I don't know if this is normal or not but when I turn the ignition on the needle is just above n on the word normal on the gauge. When the wait to start light goes off I hear a click and the needle goes to the left and below the N. I thought it was the batteries so I replaced them and cleaned the terminals. It is still doing it. My dads 99 f-350 diesel initially registers lower on voltage and then when the glow plugs turn off the needle jumps to the right.
When the truck is running for a minute the needle goes to m on normal but not right away after starting.
should I worry or not it seems odd
jeff
</td></tr></tbody></table>
<table itxtvisited="1" border="0" width="100%"><tbody itxtvisited="1"><tr itxtvisited="1"><td itxtvisited="1" valign="top">I have a 97 f-350 crew 4x4. It has two batteries and I just recently got it. I don't know if this is normal or not but when I turn the ignition on the needle is just above n on the word normal on the gauge. When the wait to start light goes off I hear a click and the needle goes to the left and below the N. I thought it was the batteries so I replaced them and cleaned the terminals. It is still doing it. My dads 99 f-350 diesel initially registers lower on voltage and then when the glow plugs turn off the needle jumps to the right.
When the truck is running for a minute the needle goes to m on normal but not right away after starting.
should I worry or not it seems odd
jeff
</td></tr></tbody></table>
Fleet Mechanic
Joined: Aug 2007
Posts: 1,508
Likes: 2
From: The boonies by Dallas OR
I have the shop manual for my '95, and it doesn't show the PCM controlling the alternator.
Note that the draw from the glow plugs is over 150A, beyond the capability of the alternator. So even if the alternator is working, a sizable current is being drawn from the batteries until the glow plugs are turned off.
Note that the draw from the glow plugs is over 150A, beyond the capability of the alternator. So even if the alternator is working, a sizable current is being drawn from the batteries until the glow plugs are turned off.
Post Fiend
Joined: Apr 2004
Posts: 12,835
Likes: 3
From: Silver Lake Dunes, MI
I have the shop manual for my '95, and it doesn't show the PCM controlling the alternator.
Note that the draw from the glow plugs is over 150A, beyond the capability of the alternator. So even if the alternator is working, a sizable current is being drawn from the batteries until the glow plugs are turned off.
Note that the draw from the glow plugs is over 150A, beyond the capability of the alternator. So even if the alternator is working, a sizable current is being drawn from the batteries until the glow plugs are turned off.
Fleet Mechanic
Joined: Aug 2007
Posts: 1,508
Likes: 2
From: The boonies by Dallas OR
I measured the alternator with a clamp on ammeter, and the alternator is putting out right from the start. The alternator "only" gives 90 Amps. The 150 to 180 amp draw of the glow plugs means that the battery is providing the remaining 60 to 90 amps - and this is right after they were walluped by the starter - so their voltage is down. When the glow plugs turn off and now the 90 amps can go to the battery, the voltage comes up quick. That's the voltage rise you're seeing.
I suspect you may have confused the dual alternator setup with the single. In the dual, the second alternator is PCM controlled and doesn't come on until the glow plugs are done.
I suspect you may have confused the dual alternator setup with the single. In the dual, the second alternator is PCM controlled and doesn't come on until the glow plugs are done.
