HELP!!! fried tach signal resistor in rb ecu.. PLEASE LOOK!!

[platez808]

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
http://i88.photobucket.com/albums/k179/droppingplatez808/IMG_1462-1.jpg
just above r414 and just below r313
http://i88.photobucket.com/albums/k179/droppingplatez808/IMG_1463-2.jpg

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]

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

[platez808]

bigger pictures added

[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 :keke:

[platez808]

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..

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 :keke:

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

[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
http://i88.photobucket.com/albums/k179/droppingplatez808/IMG_1465.jpg

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

[GSXRJJordan]

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.

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 (http://lmgtfy.com/?q=tach+signal+generator).

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.

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]

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]

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..

[Z U L8R]

tach signal pickup = msd # 8918 , clip it onto the 1 ignition 12volt power supply for all the coil packs, and wire the rest up like the instructions tell you. $30 from summit

if you try to hook the ecu's tach signal to work an autometer guage, you will pop that resistor as well so be warned.

if you pop the resistor and still need tach signal you can use either of the two 120 or 180 degree signals from the cam angle sensor (6 cyl = 120, 4 cyl = 180), for like an safc or whatever but if you popped the tach resistor the first time, don't go hooking it up to the 120/180 or you'll have even bigger problems. stop there and get a tach pick up.

Dave

[KyleT]

Sorry to bump this but

Me and a friend did the maxima/i30 tach in his car. Did everything correctly according to this guide: I30 tach in s13 cluster. Success! Lots of pics! Tach for 6 cyl! : 240sx General Discussion (http://forums.nicoclub.com/i30-tach-in-s13-cluster-success-lots-of-pics-tach-for-6-cyl-t442051.html)
But when we turned the key on we could smell something burning, traced it back to the ecu and the same resistor as the op posted is fried.

Just wondering if the fried resistor will affect anything else besides the tach, and which way we should go about getting the tach to work. Also Im not sure why it fried the resistor because we have everything wired correctly with the guide. :wtf: