making engine work with no chassis harness possible? - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

jdmlowlyfe989 · 03-02-2017, 09:29 PM

i was just curious
can i use just engine harness/trans harness
in a shell and wire up a relay for fuel pump
ignition and power for ecu?
and just run a power to the battery from alt for charge?

rawgarage · 03-02-2017, 09:48 PM

no grounds?

gaz_moose · 03-03-2017, 07:25 AM

providing you know what wire on the engine harness need powering up.

jdmlowlyfe989 · 03-03-2017, 09:41 PM

yes grounds.
just to pinout grounds on ecu

SteeleBrothersDrifting_Mike · 03-06-2017, 06:29 PM

Yes. You will also likely need to wire in a dummy light for the alternator to work depending on what motor you are using.

Audio Puppet · 04-19-2018, 07:17 PM

Quote:

Originally Posted by SteeleBrothersDrifting_Mike

Yes. You will also likely need to wire in a dummy light for the alternator to work depending on what motor you are using.

Just curious to why you need to wire a dummy light for the alternator? Is it to see if the alternator is charging the battery? I'm currently doing electrical on my track car so just making sure I'm not missing any important info.

Audio Puppet · 04-19-2018, 07:20 PM

Quote:

Originally Posted by gaz_moose

providing you know what wire on the engine harness need powering up.

Would you happen to have a link of a thread that's covers what you need to power on your engine harness/ECU? I did a lot of research but I want to make sure I wired the ECU correctly before I fire up my SR.

Kingtal0n · 04-20-2018, 02:48 PM

In the dash there is usually a bulb on older cars like pre-02 ish. One side of the bulb gets 12v switched power. the other side goes to the alternator plug. When the alternator is turning making a/c power the bulb stays off because the diode trio prevents a/c current from entering that wire that leads to the bulb. When the diodes in the alternator go bad, the bulb will light because a/c current looks like a ground to 12v, thus completing the 12v circuit.

In many applications this wire acts to 'sense' the voltage supplied to the bulb, in order to determine charging voltage. Without a 12v source with a resistor as a bulb provides (or just a resistor I guess) the alternator may not charge correctly. Some computers directly control alternator voltage through this wire, so a 'dummy bulb' can be used in those applications to bypass using the computer to control alternator voltage. Maybe someone could elaborate on the field wire now...

03-02-2017, 09:29 PM	#1
jdmlowlyfe989 Leaky Injector Join Date: Feb 2017 Location: South Carolina Age: 28 Posts: 74 Trader Rating: (2) Feedback Score: 2 reviews	making engine work with no chassis harness possible? i was just curious can i use just engine harness/trans harness in a shell and wire up a relay for fuel pump ignition and power for ecu? and just run a power to the battery from alt for charge?

03-03-2017, 09:41 PM	#4
jdmlowlyfe989 Leaky Injector Join Date: Feb 2017 Location: South Carolina Age: 28 Posts: 74 Trader Rating: (2) Feedback Score: 2 reviews	yes grounds. just to pinout grounds on ecu Last edited by jdmlowlyfe989; 03-04-2017 at 01:15 AM..

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03-02-2017, 09:48 PM	#2
rawgarage Banned from the Marketplace Join Date: Oct 2007 Location: h o u s t o n Age: 32 Posts: 5,990 Trader Rating: (75) Feedback Score: 75 reviews	no grounds?

03-03-2017, 07:25 AM	#3
gaz_moose Zilvia Member Join Date: Mar 2008 Location: engerland Posts: 242 Trader Rating: (0) Feedback Score: 0 reviews	providing you know what wire on the engine harness need powering up.

03-06-2017, 06:29 PM	#5
SteeleBrothersDrifting_Mike Leaky Injector Join Date: Sep 2012 Location: Michigan Posts: 108 Trader Rating: (0) Feedback Score: 0 reviews	Yes. You will also likely need to wire in a dummy light for the alternator to work depending on what motor you are using.

04-20-2018, 02:48 PM	#8
Kingtal0n Post Whore! Join Date: Jul 2005 Location: South Florida Age: 38 Posts: 4,646 Trader Rating: (17) Feedback Score: 17 reviews	In the dash there is usually a bulb on older cars like pre-02 ish. One side of the bulb gets 12v switched power. the other side goes to the alternator plug. When the alternator is turning making a/c power the bulb stays off because the diode trio prevents a/c current from entering that wire that leads to the bulb. When the diodes in the alternator go bad, the bulb will light because a/c current looks like a ground to 12v, thus completing the 12v circuit. In many applications this wire acts to 'sense' the voltage supplied to the bulb, in order to determine charging voltage. Without a 12v source with a resistor as a bulb provides (or just a resistor I guess) the alternator may not charge correctly. Some computers directly control alternator voltage through this wire, so a 'dummy bulb' can be used in those applications to bypass using the computer to control alternator voltage. Maybe someone could elaborate on the field wire now...