"live well running" circuit?
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Elder User
Joined: Jan 2007
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"live well running" circuit?
I am looking for a 12 volt DC circuit somewhere in the vehicle that I can tap into that is live well the engine is running. Not well the ignition is on and now well the engine is cranking. Just well the engine is running.
I am looking for a turn on source for my voltage regulator for my alternators and I would prefer to have the regulator turn on AFTER the engine is done cracking. Otherwise if the regulator is on well the engine is cranking the three 205 amp alternators I have will load up the starter trying to provide electricity that the starter is consuming.
thanks.
I am looking for a turn on source for my voltage regulator for my alternators and I would prefer to have the regulator turn on AFTER the engine is done cracking. Otherwise if the regulator is on well the engine is cranking the three 205 amp alternators I have will load up the starter trying to provide electricity that the starter is consuming.
thanks.
Cargo Master
Joined: Mar 2005
Posts: 2,790
Likes: 24
From: Mount Royal, NJ
Use the Customer Access hot wire. It is a 10 amp fused wire under the dash provided for your use, and it is a hot in run only wire. Fuse # 29 in the Central Junction Box. I used mine to run my gauges. It is taped to the Diagnostic connector harness just up from the connector. You can run a relay if you need more power. The following is from the 2002 Ford Service Manual DVD:
PTO 12–volt Power Source Wire: The
wire color and circuit number changed
for 2002 model year. The former circuit
no. 295, Light Blue with Pink Trace (LB/
PK), 12–volt power for PTO circuit, is
now circuit no. 294, White with Light
Blue Trace (WH/LB); hot in the RUN
key position, and fused for 10 amps for
2002 Model Year. It can be found by removing
the modesty panel, and then
following the harness up from the diagnostic
connector mounted on the lower
edge of the instrument panel.
PTO 12–volt Power Source Wire: The
wire color and circuit number changed
for 2002 model year. The former circuit
no. 295, Light Blue with Pink Trace (LB/
PK), 12–volt power for PTO circuit, is
now circuit no. 294, White with Light
Blue Trace (WH/LB); hot in the RUN
key position, and fused for 10 amps for
2002 Model Year. It can be found by removing
the modesty panel, and then
following the harness up from the diagnostic
connector mounted on the lower
edge of the instrument panel.
Cargo Master
Joined: Mar 2005
Posts: 2,790
Likes: 24
From: Mount Royal, NJ
Whoops. Reread your post again. You want only while the engine itself is running. Not while the key is in the run position.
I just went through the 2002 diagrams for engine controls and the power distribution. The powertrain control module knows when the engine is running, but there are no wires to connect to.
The only idea I can come up with is to install a very large diode (use a battery isolator) between the battery and one of your alternators. when the engine is running, there would be power coming out of the alternator that you could tap into, but it would be effectively disconnected from battery power when the engine is not running. The tradeoff is you lose .7 volts to the diode.
With all the mods to the electrics you are making, I would hope you have wiring diagrams already.
I just went through the 2002 diagrams for engine controls and the power distribution. The powertrain control module knows when the engine is running, but there are no wires to connect to.
The only idea I can come up with is to install a very large diode (use a battery isolator) between the battery and one of your alternators. when the engine is running, there would be power coming out of the alternator that you could tap into, but it would be effectively disconnected from battery power when the engine is not running. The tradeoff is you lose .7 volts to the diode.
With all the mods to the electrics you are making, I would hope you have wiring diagrams already.
Last edited by housedad; Mar 26, 2007 at 11:54 PM.
Thread Starter
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Elder User
Joined: Jan 2007
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Originally Posted by sewerat
try looking at your tach and using a double relay sytem open by the starter and closed upon ignition
Anyway I thought the instrument cluster just had two data lines going to it? I read that somewhere.
Thread Starter
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Elder User
Joined: Jan 2007
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Originally Posted by housedad
The only idea I can come up with is to install a very large diode (use a battery isolator) between the battery and one of your alternators. when the engine is running, there would be power coming out of the alternator that you could tap into, but it would be effectively disconnected from battery power when the engine is not running. The tradeoff is you lose .7 volts to the diode.
Anyway my application is a voltage critical application and I cannot have voltage drops like that. I am running hundreds upon hundreds of dollars of wire to the back for the sole purpose to reduce voltage drop.
Cargo Master
Joined: Mar 2005
Posts: 2,790
Likes: 24
From: Mount Royal, NJ
Then rig a 10 to 15 second delay relay on the output of your alternators and the regulator line. Trigger it from the hot in run line under the dash.
No matter what you do to interrupt the circuit, you will have a voltage drop of some kind.
No matter what you do to interrupt the circuit, you will have a voltage drop of some kind.
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Senior User
Joined: Mar 2007
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I'm not a mechanic, or an electrical engineer - so be forewarned!
Could you use the fact that the vehicle voltage system is somewhere around 12 volts before the engine is turning at idle speed, and about 14 volts (presumable the factory alternator is still attached and always running) at idle?
Then you could rig up a relay that wouldn’t trip until 14 volts was present, indicating the factory alternator was up to speed. You’d have to get someone to engineer the electronics to discriminate between 12 and 14 volts but…
If you don’t still have an alternator that is always powered then this obviously wont work.
Could you use the fact that the vehicle voltage system is somewhere around 12 volts before the engine is turning at idle speed, and about 14 volts (presumable the factory alternator is still attached and always running) at idle?
Then you could rig up a relay that wouldn’t trip until 14 volts was present, indicating the factory alternator was up to speed. You’d have to get someone to engineer the electronics to discriminate between 12 and 14 volts but…
If you don’t still have an alternator that is always powered then this obviously wont work.
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Junior User
Joined: Mar 2007
Posts: 55
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From: New Madison, OH
Originally Posted by housedad
Use the Customer Access hot wire. It is a 10 amp fused wire under the dash provided for your use, and it is a hot in run only wire. Fuse # 29 in the Central Junction Box. I used mine to run my gauges. It is taped to the Diagnostic connector harness just up from the connector. You can run a relay if you need more power. The following is from the 2002 Ford Service Manual DVD:
PTO 12–volt Power Source Wire: The
wire color and circuit number changed
for 2002 model year. The former circuit
no. 295, Light Blue with Pink Trace (LB/
PK), 12–volt power for PTO circuit, is
now circuit no. 294, White with Light
Blue Trace (WH/LB); hot in the RUN
key position, and fused for 10 amps for
2002 Model Year. It can be found by removing
the modesty panel, and then
following the harness up from the diagnostic
connector mounted on the lower
edge of the instrument panel.
PTO 12–volt Power Source Wire: The
wire color and circuit number changed
for 2002 model year. The former circuit
no. 295, Light Blue with Pink Trace (LB/
PK), 12–volt power for PTO circuit, is
now circuit no. 294, White with Light
Blue Trace (WH/LB); hot in the RUN
key position, and fused for 10 amps for
2002 Model Year. It can be found by removing
the modesty panel, and then
following the harness up from the diagnostic
connector mounted on the lower
edge of the instrument panel.
Check this wire, I bet you find its not hot while the key is in the *Start* position. this would be typical for a gas application. they used to run a wire with a diode in it to the coil from the starter, so the the coil would have power while cranking. because the keyswitch disengaged the *run* circuit while in *start*.
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