Help me chase some wiring - S13, black/yellow chassis wire - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

Abeo · 07-13-2022, 01:05 PM

I've been trying to figure out my idle problems with my 89 240sx with a S13 SR20 blacktop and standalone. Long story short, I've chased down the wiring and I'm not getting power on the black/yellow wire... instead, it's grounded. Looking at the FSM, it should be getting 12v key on.

Does anyone know where the black/yellow wire runs under the dash, between the large plug and the power source?

I've ruled out: the swap wiring, the chassis wiring from the brown plug to the dash plug. The ground seems to be coming from under the dash, which has me confused as it's stock under there. No other problems, no blown fuses.

If I can't figure this out, I'll just run switched power to it... but it's bugging me.

edit: I'll be looking into the starter relay next to see if it's the culprit

slider2828 · 07-13-2022, 03:33 PM

There are also 2 huge blue ecu relays near the passenger side headlight. Those are what feeds the ecu power.... I would check those out as well

Abeo · 07-13-2022, 09:56 PM

Quote:

Originally Posted by slider2828

There are also 2 huge blue ecu relays near the passenger side headlight. Those are what feeds the ecu power.... I would check those out as well

Thanks, I looked into that but that seems like a US-only thing.

Abeo · 07-14-2022, 12:23 PM

update: black/yellow for the ignition system is huge and not part of the small 18 ga black/yellow circuit.

Traced the 18 ga black/yellow circuit to the fuel pump. Looks like I have an internal short on that side.

Abeo · 07-18-2022, 08:57 PM

ugh, I'm an idiot.

I traced the black yellow to the fuel pump... it seems grounded when the fuel pump isn't running. The fuel pump gets power for about 3 seconds with key on and not running, then turns off. I was checking after the 3 seconds. For anyone searching this in the future, on the s13 the black/yellow goes from the battery, across the rad support, up the fender, into the dash and through the SMJ, down the side into the trunk and across the tail light panel to the tank plug.

Turns out my IACV problems were probably from tuning around a crappy old IACV; I changed the minimum opening time from 25% to 0% and now it's idling like it's supposed to.

jr_ss · 07-18-2022, 09:19 PM

Quote:

Originally Posted by Abeo

ugh, I'm an idiot.

I traced the black yellow to the fuel pump... it seems grounded when the fuel pump isn't running. The fuel pump gets power for about 3 seconds with key on and not running, then turns off. I was checking after the 3 seconds. For anyone searching this in the future, on the s13 the black/yellow goes from the battery, across the rad support, up the fender, into the dash and through the SMJ, down the side into the trunk and across the tail light panel to the tank plug.

Turns out my IACV problems were probably from tuning around a crappy old IACV; I changed the minimum opening time from 25% to 0% and now it's idling like it's supposed to.

Live and learn, thanks for updating.

07-13-2022, 01:05 PM	#1
Abeo Leaky Injector Join Date: Oct 2011 Location: Calgary, Ab Age: 44 Posts: 62 Trader Rating: (0) Feedback Score: 0 reviews	Help me chase some wiring - S13, black/yellow chassis wire I've been trying to figure out my idle problems with my 89 240sx with a S13 SR20 blacktop and standalone. Long story short, I've chased down the wiring and I'm not getting power on the black/yellow wire... instead, it's grounded. Looking at the FSM, it should be getting 12v key on. Does anyone know where the black/yellow wire runs under the dash, between the large plug and the power source? I've ruled out: the swap wiring, the chassis wiring from the brown plug to the dash plug. The ground seems to be coming from under the dash, which has me confused as it's stock under there. No other problems, no blown fuses. If I can't figure this out, I'll just run switched power to it... but it's bugging me. edit: I'll be looking into the starter relay next to see if it's the culprit Last edited by Abeo; 07-18-2022 at 08:59 PM.. Reason: wrong info

07-13-2022, 03:33 PM	#2
slider2828 Post Whore! Join Date: Oct 2004 Location: San Francisco, CA Posts: 6,040 Trader Rating: (13) Feedback Score: 13 reviews	There are also 2 huge blue ecu relays near the passenger side headlight. Those are what feeds the ecu power.... I would check those out as well __________________ Turn and Burn!

07-14-2022, 12:23 PM	#4
Abeo Leaky Injector Join Date: Oct 2011 Location: Calgary, Ab Age: 44 Posts: 62 Trader Rating: (0) Feedback Score: 0 reviews	update: black/yellow for the ignition system is huge and not part of the small 18 ga black/yellow circuit. Traced the 18 ga black/yellow circuit to the fuel pump. Looks like I have an internal short on that side.

07-18-2022, 08:57 PM	#5
Abeo Leaky Injector Join Date: Oct 2011 Location: Calgary, Ab Age: 44 Posts: 62 Trader Rating: (0) Feedback Score: 0 reviews	ugh, I'm an idiot. I traced the black yellow to the fuel pump... it seems grounded when the fuel pump isn't running. The fuel pump gets power for about 3 seconds with key on and not running, then turns off. I was checking after the 3 seconds. For anyone searching this in the future, on the s13 the black/yellow goes from the battery, across the rad support, up the fender, into the dash and through the SMJ, down the side into the trunk and across the tail light panel to the tank plug. Turns out my IACV problems were probably from tuning around a crappy old IACV; I changed the minimum opening time from 25% to 0% and now it's idling like it's supposed to.