ECU Problem/Diagnosis - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

Down2Earth · 05-27-2019, 01:06 PM

I bought my '95 240sx couple years ago and my ECU was always a bit strange, it had a small fuse hanging out of it with two wires going inside, i pretty much ignored this as the car ran fine.

So after sitting and building the car I decided it was time to properly investigate and figure out whats up with my ECU before I blow my engine over some oversight

So what the car currently does is it does not want to turn off when the ignition is off; also it does not run the smoothest, so I replace the ECU with another one and it runs absolutely spectacular; that being said I would like to fix this ECU so I opened it up to find:

Now precariously it doesnt look like the trace was burnt, rather it was split on PURPOSE? Thats interesting. But the question is; did they jump that trace and bypass some function? Is it for some kill switch setup for the ignition? if I run a wire over the cut trace and return it to "factory" will the ECU function appropriately? is this a mod of some sort for some setup?

Jfornachon · 05-27-2019, 05:48 PM

The ecu you swapped it with was not modded and it ran properly. Correct? The fuse is not adding any resistance just a fail safe if it pulls too much current that it blows and doesn't burn the ecu. You can always make a jumper and see if it changes the runnning of the car. I wouldn't think that it would.

Have a great day,
jared

Down2Earth · 05-27-2019, 05:55 PM

Quote:

Originally Posted by Jfornachon

The ecu you swapped it with was not modded and it ran properly. Correct? The fuse is not adding any resistance just a fail safe if it pulls too much current that it blows and doesn't burn the ecu. You can always make a jumper and see if it changes the runnning of the car. I wouldn't think that it would.

Have a great day,
jared

Yeah I got another ECU same P/N, color etc; and it runs like a damn top.

With this ECU the engine does not stop running when the ignition is turned off.

If it matters, when I got the engine it had aftermarket Splitfire coils

Jfornachon · 05-27-2019, 06:57 PM

So did you try what I suggested? Have you just removed the fuse? If so what happened?

Have a great day,
jared

Down2Earth · 05-27-2019, 07:17 PM

Quote:

Originally Posted by Jfornachon

So did you try what I suggested? Have you just removed the fuse? If so what happened?

Have a great day,
jared

Removing the fuse cuts the circuit for ignition, no spark obviously is no spark lol.

I'm taking the ECU to work tomorrow so I can solder a wire over the split trace on the board. Will report after I run it "native"

Jfornachon · 05-27-2019, 07:53 PM

You can just jump where the fuse is since that is what the PO did by adding the fuse and cutting the trace. You may end up damaging the board worse than it is now. That or just trim amd Seder the two wires that go to the fuse.

It does seam that it is some sort of anti theft mod. Is there anything else out of place on the board? Maybe they modded it to work witht he coils. Are you running stock coils now? Any major changes made during the build?

Have a great day,
jared

05-27-2019, 01:06 PM	#1
Down2Earth Leaky Injector Join Date: Jan 2016 Location: Toledo, Ohio Age: 27 Posts: 90 Trader Rating: (3) Feedback Score: 3 reviews	ECU Problem/Diagnosis I bought my '95 240sx couple years ago and my ECU was always a bit strange, it had a small fuse hanging out of it with two wires going inside, i pretty much ignored this as the car ran fine. So after sitting and building the car I decided it was time to properly investigate and figure out whats up with my ECU before I blow my engine over some oversight So what the car currently does is it does not want to turn off when the ignition is off; also it does not run the smoothest, so I replace the ECU with another one and it runs absolutely spectacular; that being said I would like to fix this ECU so I opened it up to find: Now precariously it doesnt look like the trace was burnt, rather it was split on PURPOSE? Thats interesting. But the question is; did they jump that trace and bypass some function? Is it for some kill switch setup for the ignition? if I run a wire over the cut trace and return it to "factory" will the ECU function appropriately? is this a mod of some sort for some setup?

05-27-2019, 05:48 PM	#2
Jfornachon Zilvia Junkie Join Date: Dec 2011 Location: Caldwell Idaho Posts: 300 Trader Rating: (3) Feedback Score: 3 reviews	The ecu you swapped it with was not modded and it ran properly. Correct? The fuse is not adding any resistance just a fail safe if it pulls too much current that it blows and doesn't burn the ecu. You can always make a jumper and see if it changes the runnning of the car. I wouldn't think that it would. Have a great day, jared

05-27-2019, 06:57 PM	#4
Jfornachon Zilvia Junkie Join Date: Dec 2011 Location: Caldwell Idaho Posts: 300 Trader Rating: (3) Feedback Score: 3 reviews	So did you try what I suggested? Have you just removed the fuse? If so what happened? Have a great day, jared

05-27-2019, 07:53 PM	#6
Jfornachon Zilvia Junkie Join Date: Dec 2011 Location: Caldwell Idaho Posts: 300 Trader Rating: (3) Feedback Score: 3 reviews	You can just jump where the fuse is since that is what the PO did by adding the fuse and cutting the trace. You may end up damaging the board worse than it is now. That or just trim amd Seder the two wires that go to the fuse. It does seam that it is some sort of anti theft mod. Is there anything else out of place on the board? Maybe they modded it to work witht he coils. Are you running stock coils now? Any major changes made during the build? Have a great day, jared