180sx harnesses w WS RB25 harness issue - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

BspeedIL82 · 06-01-2014, 07:18 PM

I finally got around to swapping in my full 180sx chassis/engine room harnesses. I got a new WS RB25 harness to ensure I didn't have any more weird wiring issues. My intent is to finally use this PFC I have had for 2 years now, and my old chassis harness has been modified more than once and wanted to eliminate any potential wiring headaches. But first...get it to run once again.

And..I am now experiencing some minor glitches lol. I turn the key into the ON position, the dash lights up, the factory ecu lights up, the fuel pump does not prime.

I have been communicating back and forth with YURY from WS over the last week to try to help figure out what is going on.

I managed to pull some data this afternoon on some resistance numbers and voltages at the ecu and across the grounds. Am hoping someone may be able to point me in the right direction.

I measured the ohms for the following pins:

10, 20 measured 7.8 ohms.
30, 50, 60, 107, 108, 116 measured 8.8 ohms.
My chassis grounds near each of the relay blocks in the engine compartment, SMJ block, near the ecu, under the RH seat, and in the trunk--all measured <1 ohm to the negative terminal on the battery.

The following pins were tested for voltage:
16 measured .88v
43 measured .05V
21 measured 9.1V
45, 49, 59, 109 measured 12V

I even grounded out the black/purple wire on the chassis plug and the FP relay clicked each time it was grounded out.

My questions, how can I improve the grounding into the ECU as that is not near the value it needs to be. I believe I have heard that some people had to ground the ECU shell itself?
And if I jump pin 13 with some power, that should turn the pump on correct?

I am curious as to why this issue. I have new relays coming, as I have replaced all fuses already.

Am I overlooking a ground somewhere on this chassis harness?? Or possibly a relay/interface?

Thanks in advance.
Brandon

dbeiler · 06-04-2014, 09:39 PM

People get confused when they use a multimeter to check grounds. It's a continuity check; resistance should be as low as possible. 0.1 ohms is a rock solid ground. After turning ignition on, the RB25 ECU should ground the FP relay (via the black/purple wire) for at least 5 seconds (to prime the fuel rail).
It's sounds like your chassis harness has a wire switched or disconnected. When swapping in RBs, people tend to modify the underdash chassis harness instead of the ECU/engine harness. Makes a mess for us guys to repair when we decide to install a new WS harness.

BspeedIL82 · 06-06-2014, 05:34 PM

The chassis harness was all factory, untouched. The RB harness was from WS. Was a full PnP scenario. Or at least thought to be (to solve my previous wiring woes).
A quick update:

I replaced all the EGI relays as a precaution. Also swapped out all the relays on the backside of the SMJ/fuse panel with known good ones.
Then I put the key in the ON position, measured the wires at the fuel pump:

1|2 3
4|5 -

1 - black/yellow 0
2 - Red/white - 12v
3 - black/white - 0
4 - black - 0
5 - Green/blue - 7.4v

as a curiosity I also cranked on the car to see if it would rotate. It does. With both the factory ecu and PFC

Since the factory ecu would allow a crank and no FP prime. I figured I would go ahead and swap the PFC in. Then I decided to measure all the power and grounding locations on the ecu (since previously I only did this on the factory one).

With the key in the ON position:
16 - 12v
18 - 12v
45 - 12v
49 - .08v
58 - 12v
59 - .08v

Grounds (measured the resistance from the pin to the negative battery terminal
10, 20, 26, 30, 50, 60, 107, 108, 116 all measured 3 ohms.

Slowly...getting there...

BspeedIL82 · 06-08-2014, 01:55 PM

Update:

I wanted to double check the ECU pins. I swapped back to the stock ECU and took voltages for the following pins, with the key in the ON position:

16- .84v
18, 45, 49, 58, 59, 109 - 12v

I then swapped over to the PFC and did the same thing:
16, 18, 45, 58 - 12v
49, 59, 109 - .08v

I then jumped the white/black and black/white at the relay near the ECU. Relay clicked in the engine bay and my controller powered on.

I did a sensor/switch scan from the controller:

ECCS was highlighted
IGN was highlighted
NTR was highlighted

The AFM measured outside the voltage parameters (MAF is not plugged up, as I am only trying to troubleshoot)

I would assume there needs to be a few more switches highlighted? Like the F/P and FP1?

06-01-2014, 07:18 PM	#1
BspeedIL82 Zilvia Member Join Date: Jun 2009 Location: Bloomington, IL Age: 41 Posts: 186 Trader Rating: (4) Feedback Score: 4 reviews	180sx harnesses w WS RB25 harness issue I finally got around to swapping in my full 180sx chassis/engine room harnesses. I got a new WS RB25 harness to ensure I didn't have any more weird wiring issues. My intent is to finally use this PFC I have had for 2 years now, and my old chassis harness has been modified more than once and wanted to eliminate any potential wiring headaches. But first...get it to run once again. And..I am now experiencing some minor glitches lol. I turn the key into the ON position, the dash lights up, the factory ecu lights up, the fuel pump does not prime. I have been communicating back and forth with YURY from WS over the last week to try to help figure out what is going on. I managed to pull some data this afternoon on some resistance numbers and voltages at the ecu and across the grounds. Am hoping someone may be able to point me in the right direction. I measured the ohms for the following pins: 10, 20 measured 7.8 ohms. 30, 50, 60, 107, 108, 116 measured 8.8 ohms. My chassis grounds near each of the relay blocks in the engine compartment, SMJ block, near the ecu, under the RH seat, and in the trunk--all measured <1 ohm to the negative terminal on the battery. The following pins were tested for voltage: 16 measured .88v 43 measured .05V 21 measured 9.1V 45, 49, 59, 109 measured 12V I even grounded out the black/purple wire on the chassis plug and the FP relay clicked each time it was grounded out. My questions, how can I improve the grounding into the ECU as that is not near the value it needs to be. I believe I have heard that some people had to ground the ECU shell itself? And if I jump pin 13 with some power, that should turn the pump on correct? I am curious as to why this issue. I have new relays coming, as I have replaced all fuses already. Am I overlooking a ground somewhere on this chassis harness?? Or possibly a relay/interface? Thanks in advance. Brandon

06-04-2014, 09:39 PM	#2
dbeiler Zilvia Junkie Join Date: Jun 2012 Location: Lancaster county, PA Age: 33 Posts: 465 Trader Rating: (4) Feedback Score: 4 reviews	People get confused when they use a multimeter to check grounds. It's a continuity check; resistance should be as low as possible. 0.1 ohms is a rock solid ground. After turning ignition on, the RB25 ECU should ground the FP relay (via the black/purple wire) for at least 5 seconds (to prime the fuel rail). It's sounds like your chassis harness has a wire switched or disconnected. When swapping in RBs, people tend to modify the underdash chassis harness instead of the ECU/engine harness. Makes a mess for us guys to repair when we decide to install a new WS harness.

06-06-2014, 05:34 PM	#3
BspeedIL82 Zilvia Member Join Date: Jun 2009 Location: Bloomington, IL Age: 41 Posts: 186 Trader Rating: (4) Feedback Score: 4 reviews	The chassis harness was all factory, untouched. The RB harness was from WS. Was a full PnP scenario. Or at least thought to be (to solve my previous wiring woes). A quick update: I replaced all the EGI relays as a precaution. Also swapped out all the relays on the backside of the SMJ/fuse panel with known good ones. Then I put the key in the ON position, measured the wires at the fuel pump: 1\|2 3 4\|5 - 1 - black/yellow 0 2 - Red/white - 12v 3 - black/white - 0 4 - black - 0 5 - Green/blue - 7.4v as a curiosity I also cranked on the car to see if it would rotate. It does. With both the factory ecu and PFC Since the factory ecu would allow a crank and no FP prime. I figured I would go ahead and swap the PFC in. Then I decided to measure all the power and grounding locations on the ecu (since previously I only did this on the factory one). With the key in the ON position: 16 - 12v 18 - 12v 45 - 12v 49 - .08v 58 - 12v 59 - .08v Grounds (measured the resistance from the pin to the negative battery terminal 10, 20, 26, 30, 50, 60, 107, 108, 116 all measured 3 ohms. Slowly...getting there...

06-08-2014, 01:55 PM	#4
BspeedIL82 Zilvia Member Join Date: Jun 2009 Location: Bloomington, IL Age: 41 Posts: 186 Trader Rating: (4) Feedback Score: 4 reviews	Update: I wanted to double check the ECU pins. I swapped back to the stock ECU and took voltages for the following pins, with the key in the ON position: 16- .84v 18, 45, 49, 58, 59, 109 - 12v I then swapped over to the PFC and did the same thing: 16, 18, 45, 58 - 12v 49, 59, 109 - .08v I then jumped the white/black and black/white at the relay near the ECU. Relay clicked in the engine bay and my controller powered on. I did a sensor/switch scan from the controller: ECCS was highlighted IGN was highlighted NTR was highlighted The AFM measured outside the voltage parameters (MAF is not plugged up, as I am only trying to troubleshoot) I would assume there needs to be a few more switches highlighted? Like the F/P and FP1?