Akira Kuramoto

iTrader: (1)

Im having alot of issues with my speedo / odometer and tach. They have become dead and im sure it is not the soldering in the cluster. I have the power fc with the controller and it is not showing any speedo read outs. I also have the defi Heads up display, It will show engine rev and no speedo. What else could be the problem? Any help is awesome, Could it be the speed sensor in the tranny?

WHTEVO

I'd start with checking the speed sensor. Good luck.

Akira Kuramoto

iTrader: (1)

what is a easy way to check the speed sensor? Also if im getting feedback in tach/rpm's isnt that pulled off the speed sensor as well?

TpCpLaYa

iTrader: (10)

the proper way is to pull it and hook up a voltmeter while spinning it to make sure its putting out ac voltage. If it checks out then inspect ALL the electronics on the back of the speedo and tach assemblies. I just went through this a little while ago and discovered a bad capacitor on the speedo which is a common problem.

Akira Kuramoto

iTrader: (1)

i know about the bad gauges and the usuall reballing of the solder, but this would not cause a dead feedback in the speed sensor to all of my gauges? As i stated I have three units that can read my speed. FC controller, DEfI HUD, Actuall gauge cluster. My tach speedo and odometer are all out. everything else works gravy.

TpCpLaYa

iTrader: (10)

well if you want to test the speed sensor...remove from the transmission and test it. I was wrong earlier about correct testing procedures....most speed sensors put out an A/C signal however that is not the case for the FD speed sensor. it puts out a digital signal and the specs are you should see a fluctuation between 0v and 12v 20 times per every SINGLE revolution of the speed sensor. You need to bench test it with a battery hooked up as i believe its a hall effect sensor...that or its optical but i doubt it.

However...you can skip all that and make sure theres a signal at the actual ECU. Dont remember what pin to check at but it should either show 0v or 5V depending on the position of the sensor...according to ALLdata

TpCpLaYa

iTrader: (10)

also your tach is in series with the speedometer. So you can have a perfect RPM signal like you said you have (as monitored by other equipment) but that signal will not be able to reach the Gauge Cluster tach if there is a problem with the Gauge Cluster speedometer/odometer.

RotorDream

wrong, if the tach and spedometer were in series if one went they would both be out, its basic electronics. the tach and spedometer would have to be in parallel!
which is wrong to, since your tach gets its signal from the CPU via IIRC the crank angle sensor while the speedo gets its signal via the spedo sensor in the tranny.

Akira Kuramoto

iTrader: (1)

thats kinda what i figured rotor. I think it was just conicendence that the spedo and tach went out at the same time which im sure is the capacitor / solder probem most people get. Now as for the speedo dropping signal is the main concern being that i can no measure it on any of my devices. so i belive this is a bit more serious than just the gauge cluster.

TpCpLaYa

iTrader: (10)

ok I stand correct....i didnt exactly mean in series but that the Tach could be completely in working condition and the SEPERATE speedometer gauge could have bad electronics and it would cause the Tach to be completely inoperative. By only replacing the speedometer gauge and not touching a single thing on the tach...the problem is solved and now both the speedometer and tachometer work.

understand?

TpCpLaYa

iTrader: (10)

here's the actual wiring diagram. As you can see..the tach is fed power seperate and then its signal seems to come through the speedometer/odometer electronics. If these electronics are bad it WILL affect the tach/

RotorDream

good catch. according to that drawing i guess it is possible that the speedometer can cause the tach to malcunction. but the confusing part is that his PFC still doesnt read out speed. meaning most likely that his speed sensor is bad or disconnected. im guessing what happened is the speed sensor maybe shorted out and possibly shorted out the CPU. id start with replacing the speed sensor after checking it, and after that replacing the CPU

Akira Kuramoto

iTrader: (1)

i replaced the speed sensor today to no adue. it still dosent not work, i belive this is leading toward a wire problem

RotorDream

that or the CPU

TpCpLaYa

iTrader: (10)

do some research into the PFC and its pin out/diagram. Find the input off the speed sensor and make sure you see some kinda of signal. easiest would be to scope it but you could probably just back probe with a multimeter and just roll the car a few feet. Like i mentioned earlier the speed sensor puts out a digital 12 volt signal 20 times every SINGLE rotation of the speed sensor. It shouldnt be hard to catch ANY of those pulses while the car is moved a few feet and it should show at the PFC pin. If you don't see anything then i would check continuity between the computer and the speed sensor.

Akira Kuramoto

iTrader: (1)

i have the pin outs for the ecu that came with the defi hud, so its simple for me to find out. I thought that having the apexi pfc might have had a different pin out but it is the same as a stock ecu, I am going to have a friend do a continuity check on the wire from the sensor to the ecu, and then from the ecu to the gauge cluster. will see what happend. i hope to god its not the pfc its self.