HELP!!! fried tach signal resistor in rb ecu.. PLEASE LOOK!! - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

platez808 · 08-13-2009, 04:38 AM

So I just did the maxima tach (pretty sure its the same exact tach as the I30) swap in my sII rb25 s13. When the needle didnt even react, I put the stock dohc tach back on and it still didnt react. This was weird considering there was a signal before, even though it was very wrong with the stock tach. So I opened up my ECU and found this:

look just above the 6 white things

just above r414 and just below r313

As you can see, it's pretty fried and unidentifiable. So what I need is for someone to PLEASE open up their ECU and identify it for me or even post up pictures of it. I was going to see if I can salvage this ECU before looking for another one. Thanks ahead of time.

s14coastie · 08-13-2009, 06:03 AM

looks like another resistor. Post bigger/better pics...Also, you need to change the one right above it too...

platez808 · 08-13-2009, 06:33 AM

bigger pictures added

*GSXRJJordan* · 08-13-2009, 06:38 AM

If you're thinking of replacing that resistor, don't bother. Much easier to get a tach-signal-generator that connects to the #1 coilpack wire for $20.

Hope the rest of the ECU is OK. BTW, you could have used a timing gun/etc to calibrate the stock tach down to be correct on the RB

platez808 · 08-13-2009, 10:58 AM

Quote:

Originally Posted by GSXRJJordan

If you're thinking of replacing that resistor, don't bother. Much easier to get a tach-signal-generator that connects to the #1 coilpack wire for $20.

Can please you point me in the right direction for a "tach-signal-generator".. i tried doing a quick search but didnt get anything solid..

Quote:

Originally Posted by GSXRJJordan

Hope the rest of the ECU is OK. BTW, you could have used a timing gun/etc to calibrate the stock tach down to be correct on the RB

Haha.. that's news to me.. where were you in the million "RB swap tach fix" threads?? can you please explain how?

platez808 · 08-13-2009, 12:30 PM

Also, while i was taking a closer look at it, i traced the connections from that fried resistor and i found this on the other side..

look at t450

i guess i need help identifying this too.. again thanks ahead of time

*GSXRJJordan* · 08-13-2009, 04:34 PM

Quote:

Originally Posted by platez808

Can please you point me in the right direction for a "tach-signal-generator".. i tried doing a quick search but didnt get anything solid..

Haha.. that's news to me.. where were you in the million "RB swap tach fix" threads?? can you please explain how?

Here's the best explanation for it, found on N*CO.

Quote:

Originally Posted by Kansei240sx @ Nico

Tach Recalibration.

1. Pull Cluster
2. Remove Backin and Clear plastic cover for the gauge.
3. Take a sharpie and mark where the needle sits on the gauge face so when you're pulling the needles off you'll know where it sits so its not screwed up when you put them back on, you can also mark the spot it sits on.
4. Remove the gauge faces.
5. Where the tachometer face is... there is a variable resistor that you can stick a screwdriver in.
6. Ussually you turn it all the way to the left.
7. Once you've done that, do this entire process in reverse order.

Now since all motors are a little different and so are the electrical outputs, you might have to pull it back out, an then turn it a litte more right and a little more right, to get it perfect. Just keep doing it untill you're satisfied or if you have an SAFC it makes it alot easier to calibrate.

When using the sharpie on your gauge cluster, to get the stuff off, all you need it some axe body spray, or some red zone body spray. Apply it to some cloth and dab it onto the area that the sharpie has been applied to and it will either slowly or pretty much instantly come off.

If i left out anything or you're still confused quote and reply to this.

As far as the tach signal generator, it connects to the +12V charging system (or injectors, or coilpack wires) and senses 'spikes' - it then outputs that signal for a tach to read.

Click here.

DEI (Directed) is the largest car audio/security manufacturer around, they make one that has been on the market for 15 yrs or so lol. Part number 454T, any car audio shop can order it for you, or you can use the link above to find it for like $20.

Quote:

Originally Posted by platez808

Also, while i was taking a closer look at it, i traced the connections from that fried resistor and i found this on the other side..

look at t450

i guess i need help identifying this too.. again thanks ahead of time

That's gonna be pretty tough, you'd have to be an engineer for that particular ECU to really know what that repair entails. Multi-layer boards are extremely tricky.

My recommendation is to see if the ECU still works, and if so, leave it alone.

platez808 · 08-20-2009, 12:24 AM

man i'm stuck.. i tried using a tach signal generator hooked up to the #1 coilpack wire instead of relying on the ecu for a tach signal but theres still no luck..

i took a multimeter to the tach signal wire while it was hooked up to the tach but not to the ecu.. and it was putting out like 8 volts when in on and 12 volts when it the engine was running.. does anyone know if this is correct? it doesnt make sense to me that there would be any voltage with the signal wire hooked to the tach but not hooked up to the ecu..

someone help me out here

platez808 · 08-28-2009, 01:01 AM

well i just went and bought a new ecu and it works fine now.. for the record its a series I ecu running a series II motor

but i also now have the part numbers for the fried stuff, so i'm going to see if i can source those parts and then replace it and see if it fixes it..

08-13-2009, 06:38 AM	#4
GSXRJJordan [JEFE S14] Join Date: May 2006 Location: << 626 >> Posts: 7,165 Trader Rating: (14) Rides Gallery: GSXRJJordan	If you're thinking of replacing that resistor, don't bother. Much easier to get a tach-signal-generator that connects to the #1 coilpack wire for $20. Hope the rest of the ECU is OK. BTW, you could have used a timing gun/etc to calibrate the stock tach down to be correct on the RB __________________ TEAM SUSPECT is alive. www.JordanInnovations.com*

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08-13-2009, 04:38 AM	#1
platez808 Join Date: May 2008 Location: Oahu Posts: 21 Trader Rating: (0)	HELP!!! fried tach signal resistor in rb ecu.. PLEASE LOOK!! So I just did the maxima tach (pretty sure its the same exact tach as the I30) swap in my sII rb25 s13. When the needle didnt even react, I put the stock dohc tach back on and it still didnt react. This was weird considering there was a signal before, even though it was very wrong with the stock tach. So I opened up my ECU and found this: look just above the 6 white things just above r414 and just below r313 As you can see, it's pretty fried and unidentifiable. So what I need is for someone to PLEASE open up their ECU and identify it for me or even post up pictures of it. I was going to see if I can salvage this ECU before looking for another one. Thanks ahead of time. Last edited by platez808; 08-13-2009 at 06:33 AM.

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08-13-2009, 06:03 AM	#2
s14coastie Leaky Injector Join Date: May 2007 Location: Hampton roads, VA Posts: 143 Trader Rating: (2)	looks like another resistor. Post bigger/better pics...Also, you need to change the one right above it too...

08-13-2009, 06:33 AM	#3
platez808 Join Date: May 2008 Location: Oahu Posts: 21 Trader Rating: (0)	bigger pictures added

08-13-2009, 12:30 PM	#6
platez808 Join Date: May 2008 Location: Oahu Posts: 21 Trader Rating: (0)	Also, while i was taking a closer look at it, i traced the connections from that fried resistor and i found this on the other side.. look at t450 i guess i need help identifying this too.. again thanks ahead of time

08-20-2009, 12:24 AM	#8
platez808 Join Date: May 2008 Location: Oahu Posts: 21 Trader Rating: (0)	man i'm stuck.. i tried using a tach signal generator hooked up to the #1 coilpack wire instead of relying on the ecu for a tach signal but theres still no luck.. i took a multimeter to the tach signal wire while it was hooked up to the tach but not to the ecu.. and it was putting out like 8 volts when in on and 12 volts when it the engine was running.. does anyone know if this is correct? it doesnt make sense to me that there would be any voltage with the signal wire hooked to the tach but not hooked up to the ecu.. someone help me out here

08-28-2009, 01:01 AM	#9
platez808 Join Date: May 2008 Location: Oahu Posts: 21 Trader Rating: (0)	well i just went and bought a new ecu and it works fine now.. for the record its a series I ecu running a series II motor but i also now have the part numbers for the fried stuff, so i'm going to see if i can source those parts and then replace it and see if it fixes it..