SAFC won't read RPM's after install

[perley03]

Well this morning my SAFC showed up via UPS and I decided to install it before I go into work later this afternoon. I did not tap anything, I soldered every connection, and I followed the wiring diagram like a church boy reading the Bible. I checked, and double checked the wiring, and everything is right, except it won't read RPM's. Its at zero, but it reads Karman, Throttle, and correction. The car is drivable as I took it around the block and it drives like normal. But it won't allow me to change anything since its not reading RPM. I probed the wire with my volt meter and its getting some voltage, but it fluctuates and I can't seem to get a good reading. Does anyone know what voltage reading I should get at idle (~750rpms)?
I even unsoldered it and resoldered the connection just to make sure, and it still doesn't read anything. I'm about ready to give up, but I might as well just leave it in there until I get another afternoon off as it is 100% drivable. Help me out guys, as this has got me thinking, and I probally won't sleep at night(well day, I work night shifts) because it's driving me nuts.

 

[spyderturbo007]

Do you have a logger? If so, what reading are you getting from the ECU?

 

[DSM90AWD]

Not sure if this is the problem or not, but I see that you also have a MAFT setup? Did you used the same RPM lead for both that and the AFC? I assume you also followed the AFC setup for #cylinders..etc?

 

[perley03]

Yes I have a logger, using pocketlogger software. It is reading from the logger but not on the safc.

As far as the MAFT setup, its all dialed to zero, and tuning with the safc. I used the same rpm wire as the maft, soldered into pin 58 on the ecu. I can get a voltage reading, buts its fluctuating between 0.052 and 0.078V at idle. I don't know if the MAFT works, as its just set to stock settings (the car came that way, I think the kid bought it just to vent, since every thing else is stock, and it has a Type-H bov).

 

[DallasN2O]

I have this same exact problem on my 90. I am using the afc neo. I tried two different wires on the ecu because it shows different on vfaq than it does on the afc instructions. Neither wire will work. I have datalogger also and have no problem getting an rpm reading from there but thats the only thing the afc wont show. Everything else works but if the afc cant see the rpms than that makes the whole unit worthless.

 

[DSM90AWD]

Do you have access to an automotive multimeter that reads a 4cyl Tach? Note that the VFAQs can be a bit confusing as the ECU pinouts are opposite what the S-AFC VFAQ shows since in the S-AFC VFAQ you are looking at the front of the harness plug not the back (if that makes any sense). Also very important to ensure the grounds are connected right (my S-AFC1 had 2 that needed specific order on the same ground line).

In any case, the RPM Pinout should be #21 (the CAS signal).

Note that there is also a diagnostic tach plug taped to the main harness on the P/S firewall which can be used to test/connect the tach signal