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HELP - Tacho not working, I think I blew the ECU

Jay95R33

By Jay95R33,
in General Maintenance

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Jay95R33 Grand Master

Jay95R33

Posted
Posted

Hmmm,

OK, here's the deal. We've been playing around with making a shift light kit. Simple freq to volt converter and a comparator.

Had it all hooked up to the car and it wasn't working, so we decided to change a capacitor. Stupid me changed it while it was still hooked up.

Now my tacho doesn't work and the ABS light just stays on (the ABS isn't working - I tested that !!). I MAY have shorted the tacho ECU output to ground or 12v+ for a split second.

We hooked a signal generator up to the tacho on the dash and it swung around, so that's working. It looks like there's no signal coming out of the ECU for the tacho :P;)

Has anyone else had this???? The strange thing is that the ABS light stays on now !!!

I've checked all the fuses and they (dash, boot, bonnet) are fine. Did the diag's on the ECU and it came up with 55 - all is OK.

Does anyone know where the ABS fuse is??? It's all in Jap.

If it is just the ECU it's not too bad cause I'm getting a new ECU in a week or two, but the ABS thing has got me worried.

Help me Obi Wan Kanobi - your my only hope.........

J :):(

Black33 Proficient

Black33

Posted
Posted

dunno if this helps but when my battery recently went flat I jump started it and since then my air bag light would not turn off.

took it to nissan and they said it happens often when you jump start and they simply reset it in a couple if minutes by hooking it up to their computer. (but charged me $80 the bastards)

Jay95R33 Grand Master

Jay95R33

Posted
  • Author
Posted

Thanks Guys,

I'm getting a re-mapped ECU in the next week or two, so once that get's plugged in I'm hoping that everything will come back to normal.

I think what I've done is shorted the tacho output of the ECU to ground for a split second, and I think this has popped one of the chips in the ECU. And I 'think' that chip also has an output to the ABS.

If the new ECU doesn't fix the problem I'll have a good search through the car and see if I can find the problem, but I'd say it'll be a quick trip into Nissan.

Jayson

EDIT: when I get the re-mapped ECU I'll eventually get it run up on a dyno to check A/F ratios, fuel pressure, detenation etc. And I'll post up the before/after results. Should be interesting (fingers crossed).;):)

  • 2 months later...
Jay95R33 Grand Master

Jay95R33

Posted
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Posted

Bought a secondhand R33 ECU and plugged her in and all is good now.

Tacho works and ABS is working (light is off).

So the ABS computer must need the tacho output of the ECU to work. Just keep this in mind if your ABS stuffs up.

I pulled the cover off of the blown ECU and low and behold I totally cooked a resistor and a transistor got so hot, the solder holding it on melted and it dropped off the board.

After a quick look at the new ECU I found that the resistor was a 10 ohm 1/2 watt - about 10c from dick smiths !!!

I've put the resistor on, and soldered the transistor back on but I'm not sure if I should plug her back in to see if it's working.

BTW: surface mounted transistors are a pain in the butt to solder !!! See that little black thing in the top righthand corner with three legs on one side and one on the other, well it's about the size of a match head, and that's the sort of thing I had to solder....

I'm paranoid that I'll blow something else if it's not fixed !!!

J

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