Results 1 to 4 of 4

Thread: Bench testing cluster - speedo and rpm signals

  1. #1
    Guest speedingmofa's Avatar
    Join Date
    Nov 2012
    Location
    the Netherlands
    Posts
    608
    Rides
    0

    Bench testing cluster - speedo and rpm signals

    Hi guys, I want to test an S14 cluster on the bench so I needn't install it in the car and go for a drive to check if the tacho and speedo work. Anyone know what needs done?

    From research tacho/RPM is a 12V block signal with a 50% duty cycle. I don't have a 12V signal generator to try this out just yet (tried a 3V signal gen through bitscope micro, tried a 12V PWM fan controller also, no bueno)... But i'm contemplating on ordering a proper 12V signal generator soon.

    Now the speedo should work! But i cannot seem to get any movement. I've got a VSS sensor hooked (PIN 25 and 26) to a drill, then the cluster is powered on through PIN 14 and PIN 40 on an S14A cluster.
    So there is 12V, GND, VSS sensor +, VSS sensor -, but still nothing.

    I've read somewhere that the ABS ecu is required for the function of the speedo. Anyone know what signal/which pin i need to get the speedo to work?
    Last edited by speedingmofa; 31-07-2019 at 12:44.

  2. #2
    Guest
    Join Date
    Feb 2013
    Location
    swadlincote
    Posts
    44
    Rides
    0
    Maybe no help to you..... but I am in the process of installing aftermarket tacho, speedo, water and fuel on mine. Tacho was driven by pin 2 from the ecu. My tacho accepted a ecu input to drive it. All works good. All I know about the tacho was some people had to use a pull up system to increase the signal power for some guages.

    Speedo not attempted yet due to I have one chance to program it. But it is driven from two wires from the gearbox. Red and red/? (This is from memory) in the manual the speedo is driven from these two wires then another wire comes out to a feed into ecu.

    I dont think the abs has anything to do with the speedo. I have rebuilt all the wiring from scratch and certainly didnt see anything that connects the speedo to the abs. But like I said I haven't tested my speedo yet.

  3. #3
    Guest
    Join Date
    Jun 2009
    Location
    walsall/tamworth
    Posts
    6,744
    Rides
    0
    its only the s15 that uses the abs for the speedo.

    I would just plug them into a car, your method sound like a load of messing about.

  4. #4
    Guest speedingmofa's Avatar
    Join Date
    Nov 2012
    Location
    the Netherlands
    Posts
    608
    Rides
    0
    Quote Originally Posted by green_rs13 View Post
    its only the s15 that uses the abs for the speedo.

    I would just plug them into a car, your method sound like a load of messing about.
    Not much point in plugging them into a car that doesn't run, now is there. I have now plugged it into a friends car, and the tachometer was dead. Speedo works. But i hate to have to pull apart a mates car everytime i want to have a cluster tested...

    Quote Originally Posted by mickey1 View Post
    Maybe no help to you..... but I am in the process of installing aftermarket tacho, speedo, water and fuel on mine. Tacho was driven by pin 2 from the ecu. My tacho accepted a ecu input to drive it. All works good. All I know about the tacho was some people had to use a pull up system to increase the signal power for some guages.

    Speedo not attempted yet due to I have one chance to program it. But it is driven from two wires from the gearbox. Red and red/? (This is from memory) in the manual the speedo is driven from these two wires then another wire comes out to a feed into ecu.

    I dont think the abs has anything to do with the speedo. I have rebuilt all the wiring from scratch and certainly didnt see anything that connects the speedo to the abs. But like I said I haven't tested my speedo yet.
    Tacho in the car indeed comes from the ECU. But as any signal, it can be simulated. I was hoping there was someone with electronic knowledge in here that would share his thoughts.
    The speedo comes from the VSS sensor, which is normally connected to the gearbox. Same thing here, the sensor generates a sine wave signal. As the frequency increases, so does your speedo. Just need to find the exact properties to that signal (sine/square/triangle, duty cycle, amplitude, etc)
    Last edited by speedingmofa; 05-08-2019 at 09:11.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •