Rx7 FD - Link G4+ Extr speedo output

[Jim Szemeti]

Hi Guys
,

I'm trying to get the speedo working from the ECU Aux1 output. I have tested the speedo input to the dash by connecting straight to the T56 gearbox speed sensor (reluctor) output, this makes the speedo work (180KMH shows at about 15KMH, but hey, its working)

I cant get the ECU to drive the speedo though. I can see 6v AC coming out of the Aux output during 'sweep on key' for the first 2 secs, which looks good, but no movement on speedo when the output is connected to the dash.

I have the output connected Aux1 to Y/R and Ground Out to Y/W as shown below.

I'm thinking the Speedo doesnt like PWM and wants AC to make it work, anyone got this working with the G4+ Extreme on an Rx7 FD?

Any help much appreciated 

Jim

 

[Adamw]

Yes, if it was connected to a reluctor sensor originally it will be expecting a sine wave that crosses zero volts.  

You can try the de-coupling circuit below, no guarantees for you but it will generate a simulated AC signal that crosses zero.  It has worked for a nissan skyline speedo which is uses a reluctor sensor.

 

[Jim Szemeti]

15 hours ago, Adamw said:

Yes, if it was connected to a reluctor sensor originally it will be expecting a sine wave that crosses zero volts.  

You can try the de-coupling circuit below, no guarantees for you but it will generate a simulated AC signal that crosses zero.  It has worked for a nissan skyline speedo which is uses a reluctor sensor.

 

SORTED: Thank you so much, that worked a treat. Sweeps gauge on power on as expected now with 260Hz for 180 Kph. Now to connect the input and scale for MPH as i'm in the UK. 

Can start running in my 20B at last! :-)