Alt not charging - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

ka-t · 02-23-2012, 08:44 PM

i have a s13 redtop sr20det in a 1995 240sx , engine was pulled from my other s14 that had no charging issues . lower harness came out with the engine.

How i have the wiring setup
battery in trunk. power wire run to front of engine
using a large fuse block i have the battery wire and both white/red wires that go to the fuse box on one end and the large black/red wire out the other side.

I get 12v to the large black/red wire,so i know i have a good connection to there. Car starts fine but the alternator wont charge.

I have 1ohm through the black ground wire on the back of the alternator from post to chassi

Battery light is on and the brake light is on

I do get 12v to the wire on the connector to the alternator(yellow wire)

When vehicle is off and i check for voltage on alternator output post i have 9.09 volts and battery is at 12v. i know i have some kind or resistance in the wiring somewhere but when the car is running i have the same voltage at the post meaning that alternator is not putting anything out. so i pulled the alternator and put a ka alternator in there and tested again - still not charging

Any clues?

*wangan_cruiser* · 02-23-2012, 09:19 PM

contuinity test from the back 10mm nut of the alternator back to the fuse block that connects from the battery to the back. test it.

ka-t · 02-23-2012, 11:28 PM

so your saying test to see if i have voltage at the back of the alternator? serious ? because if i have perfect ground then my ground wire would be burning up!
Also i dont know if its a 10mm nut or 8mm bolt your talking about? no 10mm nut on a sr or ka alternator that i know of.

Also yes i will test tomorrow but if i have that happening then i surely should have blown fuse or 2 with voltage runing through my block

*wangan_cruiser* · 02-24-2012, 12:19 AM

the 10mm nut is the wire that goes to the 75amp from the fuse box then goes to the battery.

8mm is the ground and the 10mm is the wire that charges the battery. i had this problem last month that i had to swap 2 good alternators to fix the problem, then i accidentally hit the wire from the 10mm and it came off pretty easy.

ka-t · 02-24-2012, 06:52 AM

well i do get continunity because i have 9.09 volts there when the vehicle is off.So i do have a 3volt drop in the wire somewhere but its still connected. my problem is that im testing the output of the alternator at the power post and seeing nothing

greenwood · 02-24-2012, 11:59 AM

not sure if the same with your setup. On the RB20, there is a wire that goes from the alternator to a resistor on the dash. If not wired your alternator will not charge. When you turn your key on, you should see the alternator dummy light go on. Then when you fire it up it should turn off. If it is not doing either of these, then that is more than likely your problem.

ka-t · 02-24-2012, 01:19 PM

battery light is on so it sees its not charging.

I dont know what that wire does though. Does it send the cluster 12 volts from the alternator?

GroundPerformance · 02-24-2012, 01:44 PM

Verify the 75amp fuse.. and make sure the main power connection to the ALT is not shorting out.

greenwood · 02-24-2012, 02:14 PM

you need to have a wire running to that light on your dash. Or you can wire in a resist to make the alternator is hooked up to the dash light. It is a silly thing, but I'm pretty positive this will fix your issue. do searches to read more.

the little light is a form of resistor that lets the alternator know to start charging. without it no dice on charging anything.

vertsilvia93 · 01-13-2020, 08:17 AM

Quote:

Originally Posted by greenwood

you need to have a wire running to that light on your dash. Or you can wire in a resist to make the alternator is hooked up to the dash light. It is a silly thing, but I'm pretty positive this will fix your issue. do searches to read more.

the little light is a form of resistor that lets the alternator know to start charging. without it no dice on charging anything.

how or where could I find out how to do this?

greenwood · 01-13-2020, 09:00 AM

Quote:

Originally Posted by vertsilvia93

how or where could I find out how to do this?

Sorry man, I posted that 8 years ago when I had a similar issue when I rb20 swapped my s13. You have to do some wire tracing or digging on the internet about the issue.

If you are going to tune/fix/tinker on these cars you have to use the wealth of knowledge already available. Guy mentions the charging dash light here as well. I found that info within a 10 second google search.

https://zilvia.net/f/showthread.php?t=634905

greenwood · 01-14-2020, 07:13 AM

Also if your intimidated by using a multimeter, dont be just watch youtubes on it and get one from harbor freight for 6 bucks they are cheap and work well.

vertsilvia93 · 01-14-2020, 08:00 AM

Quote:

Originally Posted by greenwood

Also if your intimidated by using a multimeter, dont be just watch youtubes on it and get one from harbor freight for 6 bucks they are cheap and work well.

trust me I have done hours and hours of research. I have a multimeter. The battery light on the dash is the exciter for the alternator. The light does not turn on when the key is on the on position. i am going to just run a wire directly from the alternator to the back of the gauge cluster. There might be a break in the wire.

racecar11 · 02-26-2012, 01:17 PM

Can I get an update on what the problem was here? Im researching the same issue and need some more feed back.

ka-t · 02-26-2012, 01:21 PM

umm my update is that its working now and im and idiot - lol
i put the alternator wire from the alternator to the post in the fuse box . well that post went nowhere lol and the car i pulled the engine was wired differently . so all my fault

S14rebuild · 01-14-2020, 11:33 AM

On my s14 i ditched stock cluster...i just ran the 12volt feed to the cluster to the alternator battery light wire on the harness and boom, alternator turns on and charges just fine...was super simple.

Alternator connector has key on 12v and a constant 12v feed from battery.. very simple

vertsilvia93 · 01-14-2020, 11:48 AM

Quote:

Originally Posted by S14rebuild

On my s14 i ditched stock cluster...i just ran the 12volt feed to the cluster to the alternator battery light wire on the harness and boom, alternator turns on and charges just fine...was super simple.

Alternator connector has key on 12v and a constant 12v feed from battery.. very simple

so just run a extra 12v source to the red and white wire on the dash cluster harness.

S14rebuild · 01-14-2020, 02:06 PM

Key on 12v wire.. yes.

But u should see why u dont have power there to begin with n fix that first

vertsilvia93 · 01-14-2020, 02:11 PM

Quote:

Originally Posted by S14rebuild

Key on 12v wire.. yes.

But u should see why u dont have power there to begin with n fix that first

im going to see why it isn't receiving a signal

S14rebuild · 01-14-2020, 02:19 PM

https://imgur.com/vo4O3v9

Here u go! Solve away lol

vertsilvia93 · 01-14-2020, 02:25 PM

Quote:

Originally Posted by S14rebuild

https://imgur.com/vo4O3v9

Here u go! Solve away lol

thanks so much!! im gonna look at it today.

foreverdeath · 01-15-2020, 06:02 PM

All you need to do to properly setup the alternator with a aftermarket cluster is wire a 12v key on engine on voltage source to the L terminal. This works with any alternator on my K swap i have the alt hooked up to the Haltech 12v engine relay. If there is no voltage sensed at this terminal the alternator wont charge.

02-23-2012, 08:44 PM	#1
ka-t Leaky Injector Join Date: Aug 2005 Location: Arizona Posts: 128 Trader Rating: (0) Feedback Score: 0 reviews	Alt not charging i have a s13 redtop sr20det in a 1995 240sx , engine was pulled from my other s14 that had no charging issues . lower harness came out with the engine. How i have the wiring setup battery in trunk. power wire run to front of engine using a large fuse block i have the battery wire and both white/red wires that go to the fuse box on one end and the large black/red wire out the other side. I get 12v to the large black/red wire,so i know i have a good connection to there. Car starts fine but the alternator wont charge. I have 1ohm through the black ground wire on the back of the alternator from post to chassi Battery light is on and the brake light is on I do get 12v to the wire on the connector to the alternator(yellow wire) When vehicle is off and i check for voltage on alternator output post i have 9.09 volts and battery is at 12v. i know i have some kind or resistance in the wiring somewhere but when the car is running i have the same voltage at the post meaning that alternator is not putting anything out. so i pulled the alternator and put a ka alternator in there and tested again - still not charging Any clues?

02-24-2012, 01:44 PM	#8
GroundPerformance Zilvia FREAK! Join Date: Oct 2008 Location: Socal Posts: 1,479 Trader Rating: (44) Feedback Score: 44 reviews	Verify the 75amp fuse.. and make sure the main power connection to the ALT is not shorting out. __________________ SoCal KA24DET/KA24ET Owners << Join the FB Group >>

Thread Tools
Show Printable Version Email this Page
Display Modes
Switch to Linear Mode Hybrid Mode Switch to Threaded Mode

02-23-2012, 09:19 PM	#2
wangan_cruiser kouki man Join Date: Apr 2006 Location: downtown oakland,ca Age: 39 Posts: 3,535 Trader Rating: (36) Feedback Score: 36 reviews	contuinity test from the back 10mm nut of the alternator back to the fuse block that connects from the battery to the back. test it.

02-23-2012, 11:28 PM	#3
ka-t Leaky Injector Join Date: Aug 2005 Location: Arizona Posts: 128 Trader Rating: (0) Feedback Score: 0 reviews	so your saying test to see if i have voltage at the back of the alternator? serious ? because if i have perfect ground then my ground wire would be burning up! Also i dont know if its a 10mm nut or 8mm bolt your talking about? no 10mm nut on a sr or ka alternator that i know of. Also yes i will test tomorrow but if i have that happening then i surely should have blown fuse or 2 with voltage runing through my block

02-24-2012, 12:19 AM	#4
wangan_cruiser kouki man Join Date: Apr 2006 Location: downtown oakland,ca Age: 39 Posts: 3,535 Trader Rating: (36) Feedback Score: 36 reviews	the 10mm nut is the wire that goes to the 75amp from the fuse box then goes to the battery. 8mm is the ground and the 10mm is the wire that charges the battery. i had this problem last month that i had to swap 2 good alternators to fix the problem, then i accidentally hit the wire from the 10mm and it came off pretty easy.

02-24-2012, 06:52 AM	#5
ka-t Leaky Injector Join Date: Aug 2005 Location: Arizona Posts: 128 Trader Rating: (0) Feedback Score: 0 reviews	well i do get continunity because i have 9.09 volts there when the vehicle is off.So i do have a 3volt drop in the wire somewhere but its still connected. my problem is that im testing the output of the alternator at the power post and seeing nothing

02-24-2012, 11:59 AM	#6
greenwood Zilvia Addict Join Date: May 2011 Location: nc Posts: 620 Trader Rating: (5) Feedback Score: 5 reviews	not sure if the same with your setup. On the RB20, there is a wire that goes from the alternator to a resistor on the dash. If not wired your alternator will not charge. When you turn your key on, you should see the alternator dummy light go on. Then when you fire it up it should turn off. If it is not doing either of these, then that is more than likely your problem.

02-24-2012, 01:19 PM	#7
ka-t Leaky Injector Join Date: Aug 2005 Location: Arizona Posts: 128 Trader Rating: (0) Feedback Score: 0 reviews	battery light is on so it sees its not charging. I dont know what that wire does though. Does it send the cluster 12 volts from the alternator?

02-24-2012, 02:14 PM	#9
greenwood Zilvia Addict Join Date: May 2011 Location: nc Posts: 620 Trader Rating: (5) Feedback Score: 5 reviews	you need to have a wire running to that light on your dash. Or you can wire in a resist to make the alternator is hooked up to the dash light. It is a silly thing, but I'm pretty positive this will fix your issue. do searches to read more. the little light is a form of resistor that lets the alternator know to start charging. without it no dice on charging anything.

01-14-2020, 07:13 AM	#12
greenwood Zilvia Addict Join Date: May 2011 Location: nc Posts: 620 Trader Rating: (5) Feedback Score: 5 reviews	Also if your intimidated by using a multimeter, dont be just watch youtubes on it and get one from harbor freight for 6 bucks they are cheap and work well.

02-26-2012, 01:17 PM	#14
racecar11 Leaky Injector Join Date: Feb 2008 Location: Utah Age: 34 Posts: 106 Trader Rating: (0) Feedback Score: 0 reviews	Can I get an update on what the problem was here? Im researching the same issue and need some more feed back.

02-26-2012, 01:21 PM	#15
ka-t Leaky Injector Join Date: Aug 2005 Location: Arizona Posts: 128 Trader Rating: (0) Feedback Score: 0 reviews	umm my update is that its working now and im and idiot - lol i put the alternator wire from the alternator to the post in the fuse box . well that post went nowhere lol and the car i pulled the engine was wired differently . so all my fault

01-14-2020, 11:33 AM	#16
S14rebuild BANNED Join Date: May 2019 Location: Florida-FAIL Posts: 2,495 Trader Rating: (8) Feedback Score: 8 reviews	On my s14 i ditched stock cluster...i just ran the 12volt feed to the cluster to the alternator battery light wire on the harness and boom, alternator turns on and charges just fine...was super simple. Alternator connector has key on 12v and a constant 12v feed from battery.. very simple

01-14-2020, 02:06 PM	#18
S14rebuild BANNED Join Date: May 2019 Location: Florida-FAIL Posts: 2,495 Trader Rating: (8) Feedback Score: 8 reviews	Key on 12v wire.. yes. But u should see why u dont have power there to begin with n fix that first

01-14-2020, 02:19 PM	#20
S14rebuild BANNED Join Date: May 2019 Location: Florida-FAIL Posts: 2,495 Trader Rating: (8) Feedback Score: 8 reviews	https://imgur.com/vo4O3v9 Here u go! Solve away lol

01-15-2020, 06:02 PM	#22
foreverdeath Zilvia Junkie Join Date: Sep 2012 Location: va beach Age: 31 Posts: 321 Trader Rating: (3) Feedback Score: 3 reviews	All you need to do to properly setup the alternator with a aftermarket cluster is wire a 12v key on engine on voltage source to the L terminal. This works with any alternator on my K swap i have the alt hooked up to the Haltech 12v engine relay. If there is no voltage sensed at this terminal the alternator wont charge.