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

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.
Modified by platez808 at 4:50 AM 8/13/2009

[platez808]

bigger pictures added

[Sil240]

Does the car run???If so then hop on a Dakota Digital tach adapter. It'll pick up the signal from the coils.

I think I might have the same problem.My tach puts out NO signal.

I have to check out my ECU to see if mine is burnt also.

[platez808]

The car runs fine, but it has no tach signal.

I guess the dakota box is an option, but i figured that if i can get help identifying that really messed up resistor by looking at the picture or cracking open their own ECU, then i can try replacing them and seeing if that fixes it.

If replacing it doesn't work then yah.. most likely i'll go the next cheapest route, either another ecu or dakota.. but until then, someone please HELP ME OUT!! haha

[Sil240]

I def would be interested in knowing also.

Maybe if you take a multimeter on each side of the resistor and trace it to the pin on the ECU.Then you could see where the Short is.

I suck with electronics straight up, so I wont be much help.But I know there are a couple guys with the same problem.

I believe that Pin # 7 should be the Tach signal to the Cluster and to the little Test port in the engine bay (red/yellow stripe iirc).

[platez808]

That really burnt one is definitely connected to the pin7 which is for the tach signal. So i need someone with a work RB ecu to look at theirs to tell me or show me what it looks like and whats on it to help identify it so that i can try to replace it.

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

[Fibre guy]

Did you by any chance reverse the tach signal and the ignition wires? It looks like you supplied it with the 12v ign source... Hope it helps. My tach works fine but the speedo doesn't match with the mph for just the rb25's. I'm switching back to my r33 gauge cluster when I finish my new dashboard.

[platez808]

I'm pretty sure that i didn't reverse it. Like how you did in your conversion, my hole that i drilled for the TAM signal is right by the plug right over the actual TAM copper connector thing. But it does look like there was a short and totally annihilated that resistor.

In other news, someone did try to check their ECU for me and found that it was a beige resistor with brown, black, black, and gold stripes from L-R. This should make a 10ohm +/-5% tolerance. Can anyone verify this for me please? I still need to identify the black one in the back. I know it says ES on the top and then 3 numbers/letters on the bottom, but I'm unclear on the bottom set. So yeah, let me know. Thanks again.

[Fibre guy]

Something had to have caused it though. Did any of your wires cross any copper strips? I'm really interested in knowing so I can add a warning about it to my write-up.

[20DET]

is it hard to get a ecu for this in america??? i can get one in nz for like 20bux lol thats all they go for over here

[platez808]

maybe it did cross.. what i did though to make sure it didnt happen was put a layer of electrical tape around each hole i drilled, to cover atleast the area of the ring terminal things to prevent anything touching.

and in terms of getting the ecu in america, it's not hard but it isnt cheap either as with anything else pertaining to these motors. get one ecu for me and send it down if its so cheap and bountiful

[20DET]

well i dno how much shiping would cost all the way to usa

[Fibre guy]

I completely cut all the copper/plastic away from any of the holes and eye crimps. That was why I used the new wires.

[platez808]

haha.. i did that too.. i cut away and then used tape..

[platez808]

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

i took a voltometer 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

[maik21]

u can use megastimulator ( megasquirt sensor simulator ) to test ur tach !!

[Fibre guy]

Are you absolutely sure that the maxima tach is the same as the I30?

[platez808]

well i just bought a replacement ecu.. guy sent me a series I when he told me it was series II.. but it works..

and i guess i can confirm that the maxima tach does work.. from the layout and the looks of the tach, it does look exactly the same as an I30 tach.. i'm sure its accurate.. redlines right at 7k.. no hesitation from the tach that i notice..

in terms of the old ecu.. now that i have a working ecu i can find out for myself what the broken part is and if i can source it then i'm going to try to fix it, to maybe give hope to those all over the world with fried tach outputs

[lexrob]

WOW i have same problem and even found the burnt resistor. Tried new ecu and still nothing paid 100$ and im guessing i fried that crap too. Wish i would have found this thread earlier. Im pretty good with an iron did you confirm the resistor?

I thought i fried my old ecu when it puffed out smoke when i was going through wiring. Grounded my inj. from the brown block when i found a snapped off wire and puff!!! Any ideas my tach worked before and i didnt change anything but that ground. (pin out shows them all straight to ground)like pins 109,116,108 sumthin like that.

[RustspecS13]

I

Are you absolutely sure that the maxima tach is the same as the I30?

I'm using a 89-94 maxima tach with my RB20. It should work no problems for any rb. I'm not sure about other year maximas, I had an extra gauge cluster from a maxima I parted out a few years ago.

~Alex

[Fibre guy]

and i guess i can confirm that the maxima tach does work.. from the layout and the looks of the tach, it does look exactly the same as an I30 tach.. i'm sure its accurate.. redlines right at 7k.. no hesitation from the tach that i notice..

I was starting to worry about it not working with all rb ecu's. Thanks for the update, I didn't catch it until now.

[KyleT]

What did you end up doing to fix this? It seems I have everything wired up correctly in the guide, but the same resistor is fried. Its not as bad as yours but Im assuming its still probably toast. Would I be able to just get the resistor replaced? What causes the resistor to fry?