Jump to content
SAU Community

Tach doesn't work ECU burnt...

USRB25S13

By USRB25S13,
in Engines & Forced Induction

 Share

Recommended Posts

USRB25S13 Enthusiast

USRB25S13

Posted
Posted

My tach have never worked since I did my swap into my S13. The engine is a 95.5 RB25DET. When I first got the clip I took the ECU out and I noticed a "hot burnt" smell coming form the ECU. (no smoke or anything) Since the engine ran fine I didn't think much of it till I finished the swap and found out tach wouldn't work. I checked my wiring to make sure that was right. I then checked for a signal from the ECU and got nothing (No AC/DC or Hz signal) I then opened the ECU and found a burnt part on the circuit board.....the car drives ok but just no tach.

I have located and purchased a used ECU and before I hook it up I want to check and make sure my tach isn't shorted so I don't burn my new ECU. Does anyone know what a normal tach should measure for resistance? I plan to physically move the tach through it's full range to make sure it doesn't show low resistance to ground or power at any point. Is this a comman problem for them to just burn up for no resound?

Link to comment
https://www.sau.com.au/forums/topic/35900-tach-doesnt-work-ecu-burnt/
Share on other sites
BigDatto Proficient

BigDatto

Posted
Posted

Hi USRB,

Did you check this thread ? http://www.skylinesaustralia.com/forums/sh...ead.php?t=22535

Maybe your tacho is drawing too much voltage/current. I have no first-hand experience, but drawing 12v from an 8v rail could explain the carbon & freon smells from your ECU.

hope you sort it soon !

rsx84 Veteran

rsx84

Posted
Posted

i've just put in a autometer 5" tacho and seem to have the same problem its ither there not enough power going to the tacho or i've cut the wrong wire on the tacho or there is no tacho pulse from the ecu ??

what it does is just sit on 3000 rpm and not move, when i remove the wire from the ecu it goes back to zero, the instructions said to cut the brown wire loop which i did???? any ideas

BigDatto Proficient

BigDatto

Posted
Posted
I tested my tach. I saw 8v with the wire unhooked from the ECU. I grounded the wire and it moved. So I put my new ECU in and it works now! I am soo excited. After driving a month without a tach. lol  

I put an inline a 1 amp fuse in the wire just to be safe.

Cool !

You kicked that one squaw in the nootz !:kick:

rsx84 Veteran

rsx84

Posted
Posted
I tested my tach. I saw 8v with the wire unhooked from the ECU. I grounded the wire and it moved. So I put my new ECU in and it works now! I am soo excited. After driving a month without a tach. lol  

I put an inline a 1 amp fuse in the wire just to be safe.

so it was your ecu that was the problem then!

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing


  • Similar Content

  • Latest Posts

    • GTSBoy
      New kid on the block

      By GTSBoy · Posted

      The wiring diagram for the R33 RB25 is freely available, and is essentially the same same as most other RBs (just with differences as to which pin # does which job). To get the ECU to power up, you just need to provide power to the ECCS relay, and have the other power feeds that come in from the top left of the wiring diagram (wrt the ECU) that give perma power to the fuel pump relay, the ECU itself, etc etc, all connected. When you put power on all these it will just come to life. It's pretty clear from the diagram what needs to happen. Just follow the lines from the 12V + supply stuff in the top left over towards the ECU. I've even posted snips of such diagrams (not for vanilla 25, I think for Neo and 26) to various threads here in the last few months, talking about what it takes to get the fuel pump and FPCM up and going. Search these up and they will help get you started on doing the same with the vanilla 25 diagram. Hell, for all I know, I've done the same with that one in years past and have forgotten.
    • Duncan
      New kid on the block

      By Duncan · Posted

      Yep...so unless someone posts up the answer you will need to probe from the ECU connector to the dash plug with a multi meter in continuity mode to trace the wires.  Note the ECU has multiple - and + (and across different key settings - Battery, IGN and Start) and most likely the power is fed from the connector(s) that is normally near the left hand headlight.
    • Songo
      New kid on the block

      By Songo · Posted

      Thanks Duncan, I am actually just trying to get the Rb turning and running with the RB25DET S2 original loom itself  I am just trying to get it going outside the body and not thinking about the S15 or trying to match anything to the S15 loom at all I am only trying to see if anyone has done this and what pin they found to be the ignition trigger and ECU+/- on the dash connector, that's about it. Thanks  
    • iain_ST44GA
      M35 VQ25DET starter motor

      By iain_ST44GA · Posted

      Hi Guys, Does anyone know any aftermarket part numbers for a starter motor to suit the VQ25DET? I can find lots of alternative part number for the VQ35DE, which I assume would fit, but there is a lot of conflicting information out there. Thanks..
    • Murray_Calavera
      R33 GTR running -9 with no tune

      By Murray_Calavera · Posted

      I don't understand how this hasn't boiled down to - Upgrade the turbo when you have everything required. ECU, injectors, fuel pump, turbo, etc. Do it all at once.  If you don't have everything required, just enjoy the car as it is and keep saving up your pennies. 
×
×
  • Create New...