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VSS issue, K20 swap Fiat X1/9

3K views 0 replies 1 participant last post by  TVR 
#1 ·
Hi,
I have completed my K20 swap for my Fiat X1/9. The car runs really well, but I have an issue with the VSS signal. Been searching but haven’t been able to find a straight answer, so posting a new thread.

I am using Hondata K-Pro and have made all connections according to the wiring diagram supplied by Hondata.

Issue: When using the “ECU A18 VSS” output (from connector C101) for my aftermarket speedo, I get a working speedo but VTEC won’t engage nor does the reverse lockout work. Apparently the ECU gets no speed signal and I get a “VSS malfunction” error code. VTEC does however engage if I disconnect the speedo and just leave the wire as a dead end, a bit strange …

Also the E connector has a pin for speed signal (25), visible in the Hondata diagram. Not connected on my car, since no connection is shown in the diagram. I figure this must be where the VSS signal is going into the ECU, even though it says “Speed Sensor OUTPUT” instead of “INPUT”? There’s an output on my aftermarket speedo (from Stack), producing a 5 volt DC square wave signal. Perhaps this could be connected to pin 25, so that the VSS runs from the sensor on the tranny, via the speedo to the ECU?

Or is it better to split the wire from pin ECU A18 VSS, connecting it both to pin 25 on the E connector AND the speedo?

I know that I can set constant speed or “0 mph” in K-Pro, but what happens with the reverse lockout if I choose this option?

Appreciate all help! /Stefan in Sweden
 

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