Speedometer calibration help w/ or w/o JayCar calibration unit.

[madhushankarox]

I'm running a 1996 Nissan Caravan coach with an incompatible Vehicle Speed Sensor (5096 pulses per Km (85Hz @ 60Kmph)),
possibly after converting automatic to manual gear and the Yazaki meter I got on the cluster says 169.9Hz = 60Kmph (10192 pulses per Km).
So I read 50% off from the actual speed / distance.


Sensor output is a 5v square wave.
Frequency will be 0Hz to 300Hz (85Hz = 60Km/h)

Speedometer rated as 169.9Hz = 60Kmph

Here is the speedometer's PCB:




I have tried JayCar speedometer calibration unit too. But...It was failed to detect the input signal from the sensor.




Some one gave me a hint:

your driving it with the wrong signal type... 5096 pulses per km (85Hz @ 60) is the norm,
add a 10uF cap in series with your input signal and add a 1K resistor on the circuits side of the cap to ground

So I've added a 10uF capacitor and a 1K resistor to the circuit and tested with a 169.9Hz wave.
But the speedometer still reads 60Kmph



C2 (1uF / 50v) is the stock capacitor I had.

[Shonky]

Well technically 5100 pulses/km is 85Hz at 60km/h. That is not the reason you would put a filter in it like that.

If the sensor is 5V and you're sure of that, I would expect the Jaycar unit to understand it.

Edit:Wrong.

You need to double the frequency. Technically that thing will only get you to 99% (i.e. not quite double)

[MexicanBatman]

put on dyno, pull needle off and run up to speed and put needle back on

worked for me a few times, and wasn't using a dyno, didnt die

[madhushankarox]

put on dyno, pull needle off and run up to speed and put needle back on

worked for me a few times, and wasn't using a dyno, didnt die

didn't work for me. needle not going to 0Kmph

[madhushankarox]

I tried to detect signal by setting

- Set S1 to 2
- Set S2 to A
- Install link LK2

and it never worked for me. LK3 either

[Shonky]

put on dyno, pull needle off and run up to speed and put needle back on

worked for me a few times, and wasn't using a dyno, didnt die

How the fuck is that ever going to work? All that does is change the offset. What's needed here is to scale it.

I tried to detect signal by setting

- Set S1 to 2
- Set S2 to A
- Install link LK2

and it never worked for me. LK3 either

Have you looked at the actual signal out of the sensor on a oscilloscope to make sure it looks legit? There's only 3 wires needed for that part so not much you can get wrong (unless you got them wrong?)

LK1? If 5V, that's what the manual says you need. LK3-5 are for the output. Get the input working first.

[madhushankarox]

Have you looked at the actual signal out of the sensor on a oscilloscope to make sure it looks legit? There's only 3 wires needed for that part so not much you can get wrong (unless you got them wrong?)

I didn't try with an oscilloscope. But the speedometer works fine with the sensor (the issue is 50% off from the actual speed).

Sensor is a 3 wire speed sensor.

+5V supply
Ground
Signal

I've test the sensor output with my multimeter. It reads 0v and 5v when I rotate the axle / tire. Sensor is working as a on / off switch? (hall effect sensor)

Thanks for your support to fix this issue. I really appreciate it. I want to get this issue fixed some how.

LK1? If 5V, that's what the manual says you need. LK3-5 are for the output. Get the input working first.

I've tried both LK1 and LK2. Both are not working. How long it will need to run? How many KM's?

[TRD-MX62]

get a speedo off speedhut.com, bin original unit

[madhushankarox]

How the fuck is that ever going to work? All that does is change the offset. What's needed here is to scale it.


Have you looked at the actual signal out of the sensor on a oscilloscope to make sure it looks legit? There's only 3 wires needed for that part so not much you can get wrong (unless you got them wrong?)

LK1? If 5V, that's what the manual says you need. LK3-5 are for the output. Get the input working first.

And if you check the Speedo corrector PCB it is different from the old JayCar's one. It's from TechBrands http://techbrands.com/store/product/aa0376.aspx However there is some settings to set-up this unit manually? Please see this diagram (top right corner)

[BMWTurbo]

The Speedo will have a calibration resistor on the board somewhere, that you can modify to adjust the speedo.

I've calibrated VN Commodore and BMW E30 and E32/34 speedo's this way.

[madhushankarox]

The Speedo will have a calibration resistor on the board somewhere, that you can modify to adjust the speedo.

I've calibrated VN Commodore and BMW E30 and E32/34 speedo's this way.

Thanks for the reply.. Any thoughts about this PCB?



I cannot find the calibration resistor

[BMWTurbo]

Here is what I found with the BMW Speedos.

[Xnke]

http://forums.hybridz.org/topic/9267...%2Bspeedometer

Big Tim and I worked out how to change the speedo about, mixing pre-95 VSS units and post-95 speedometers.

[madhushankarox]

http://forums.hybridz.org/topic/9267...%2Bspeedometer

Big Tim and I worked out how to change the speedo about, mixing pre-95 VSS units and post-95 speedometers.

Thanks for the reply.. There is no adjustments in my PCB

[agentcrm]

I know on VR Commodores you can adjust the speedo by changing the value in the ECU programming.