No Tach signal out of the ECU Pin# 7??????

[Sil240]

Car: S13 SOHCEngine: RB20Ecu: Stock

I've now found out that I have no Tach signal coming from the ECU. I've tested the #7 pin on the ecu and no voltage comes out, and I've also hooked up a wired under the hood. ( the wire that's in that little tube with the cap on it)

I belive my tach works (aftermarket DEFI), I've used it before and when I touch the signal wire for a QUICK sec to the + side of the bat the needle jumped.

Anyone have any ideas on that??

[krayton]

u sir are way crazy for putting your defi tach right to the battery.

but whats the instructions on the defi tach? the stock tach signal is really tiny. not a 0-12volt reading (at least on my 25)

some aftermarket tachs might have u connect to the coils since thats a stronger reading. really dont feel like searching for those instructions on the web though

[Sil240]

Yeah i know.For that QUICK touch to the batt, it jumped up to 3,000 something rpm. lol

I wasn't sure if it was the tach that was bad, maybe from being knocked around.

I've used this same tach with this same ecu and harness. About 1.5 years ago.It was reading fine.

Now there's NO signal coming out of the harness. After this guy wired it for me.I would just call him back, but to get him is a HUGE PITA!!!

So I'm going to try to figure out whats wrong.I HATE wiring!!!

[Darius]

Your RPM signal is based on your CAS, correct? I would start there first. Then again your ECU could be busted in that department. The signal is interpreted by the ECU then sent out through pin #7 to the tach. So if you're not getting a signal at all, there's obviously something wrong in between.

[Sil240]

Well I have to be getting a Signal from the CAS, because the motor is running.

But... there might be a specific engine speed wire from the CAS though.....

I gotta look into that when I get home.

P.s. Thanks for the help/input guys

[Sil240]

CARL H or anyone!!!

Now I'm on my second wiring harness.And I had Carl wire the harness for me.It plugged and and started right up.So the harness wiring should be 100% right.

But I still don't have anything coming out of the ECU on PIN # 7

I have 3 Computers and they all have the same problem.

ANYONE have any suggestions???

[240z4u]

Did you plug all three ECUs into the other harness (you said it was bad?). If so you prob. damaged all 3 ecu's.

If the car runs, its not CAS. Its the tach output. I cooked mine at one point too.

[jacksonbrown]

what scale did you have your meter on? Mine only shows fluctuation on 200m

[Sil240]

240z thats def quite possible because I tried them before (with the 1st harness)

My multimeter is auto ranging so it picks up any range and adjusts.

I'm not so... distraught over not having a signal.Cause I just bought a Tach adapter.

But i really want to know the reason.I hope there's nothing else wrong.

[240z4u]

240z thats def quite possible because I tried them before (with the 1st harness)

My multimeter is auto ranging so it picks up any range and adjusts.

I'm not so... distraught over not having a signal.Cause I just bought a Tach adapter.

But i really want to know the reason.I hope there's nothing else wrong.

Yeah, I am sure you blew the tach output on all of them. Pull the lid off of the ECU, mine had blatantly burnt spots.

Evan

[Flamereka]

why not just find the CAS signal and tap that?

[Sil240]

Someone told me that the CAS sends a signal to the ECU then the ECU converts it to a different signal (like .5 volts - 2.5 volts)Can't really remember.

I just got my Dakota Digital SGI-8 in the mailI'm gonna hook it up this weekend so I can actually see how fast the engine is going.

I'm going to try and mount it under the dash near the ECU.I haven't taken a look at the wiring for it yet, but I should be able to tap into the wires on the ECU plug.

[Gammaray6666]

Ever figure this out?