please help with tach (searched)

[armysweitzer]

I have a 89 240sx with an rb20det, I have the RB gauge cluster with everything else working perfect (temp, oil pressure etc). The tach will not read for the life of me, I tried to hook up the red/yellow wire dirrectly from the ecu to the gauge cluster and that didnt work. I tried hookin up a safc from the ecu and that doesn t work either. I didnt know what to do, thanks for any help.

_Johann

[armysweitzer]

tried hard wiring the ecu-tach and touching the wires gets the tach to move but not stay in any one place, dont know if i need a resistor or what?

thanks

[ehacker01]

try hooking up a multimeter straight to the wire coming out of the ecu and see if you get any voltage reading. My multimeter even has a tach function for 4/6/8 cylinders, pick one of those up if you don't have one.

[armysweitzer]

what would i do if i didnt have any voltage? replace the ecu?

[Carl H]

do you have your dash harness properly grounded to the efi harness?if not the tach tends to not work.

[armysweitzer]

hmm idk i guess ill have to check that. Any tips on how to do that (really bad at wiring). I Know getting the dash to work could be hard but i was suprised the safc didnt work, i suppose it could be busted but idk.

thanks

[sean8564]

I bought a R32 gauge cluster and took the tach out and trimmed it up a little and put it in my s13 cluster and it works fine.

[stiergott]

I bought a R32 gauge cluster and took the tach out and trimmed it up a little and put it in my s13 cluster and it works fine.

i assumed thats what most people do. you cant run wires from the gauge cluster to the tach for some reason.

[armysweitzer]

?

[sean8564]

?

what is your question ?

[armysweitzer]

just not sure what to do, i know people have used rb clusters. Ill go back to stock if i have to just didnt know what to try next.

[sean8564]

Or you can use http://www.lsautomotive.com tach for like 100 bucks

[stiergott]

or buy an autometer tach and then get a 1 ohm drop resistor and you should be good to go. the specifics on how to do it are over on 240sxforums.

[armysweitzer]

so are my problems just because of the fact i have sohc wiring with the skyline harness? And how would a autometer tach solve my problem if the safc didnt work. thanks

[sean8564]

A LS automotive tach will solve all problems it is because the tach you have is configured for 4 cyl and you have 6 so it is off 1.5K is really 1K and 3 K is like 2K in real life.

[stiergott]

its really worse than that, when the motor is actually running at 5k the stock tach says im turning about 7500rpm. if the safc is not picking up a signal then it was installed wrong or your ecu isnt throwing out a tach signal.

[armysweitzer]

no i have the r32 tach...and its not off its not working AT ALL

[armysweitzer]

just to clarify... 89 s13 HB RB20DET, RB cluster. Everything works minus the tach...

things ive tried-hooking up safc for rpm use (flickered when tach wire was touched)-Direct wiring from dash to ecu (same effect)

#7 pinout (tach wire) is cut for some reason and there are multiple identical wires coming off of different plugs near the ecu (weird).

Any help would be greatly appreciated. I will go to a stock tach if thats what it takes just didnt know if i could use this

[mallbor240SR]

same thing happened to me with my SRmy ecu wasnt throwing any tach signal, and i didnt know what to do so i just bought an MSD tach adapter and hooked it to my coil pack harness, it works perfect.