Speedo corrector 1hz pulse

Quote:

---

Originally Posted by sierrafery

Just observed this thread and it needs a correction: the D2's VSS reference signal is 2Hz not 1Hz as in the title and this signal is used for diagnostics, the signal which is subject of correction is 8000 pulse/mile and the frequency changes according to the road speed

---

There you are.... that frequency was tested about 19 years ago and I for the life of me couldnt work out how you got 2Hz as the diagnostic frequency. It took a lot of reading and searching RAVE.

Quote:

---

ENGINE MANAGEMENT SYSTEM - V8
On vehicles with manual transmission, the SLABS signal is checked against a threshold value stored in ECM memory.
If other engine parameters indicate the engine is at high load and the VSS is below the threshold, a fault condition is
registered in the diagnostic memory.
The vehicle speed signal generated by the SLABS ECU is in the form of a pulse width modulated signal (PWM).
Pulses are generated at 8000 per mile, and the frequency of the signal changes in accordance with road speed. At
zero road speed the ECU outputs a reference signal at a frequency of 2Hz for diagnostic purposes.

---

Awesome work, thanks!

Yes, strangely they didnt describe it so well in the Td5 section too but the SLABS is the same for both engines so that 2Hz is definitely correct but it's relevant only when the vehicle is stationary

Thanks a bunch for that, didn't realise the RAVE would be that helpful (guess I should have had a proper read through it).

>The SLABS ECU generates a PWM signal switching between 0 and 12 volts at a frequency of 8000 pulses per mile.

Found this bit as well which is nice. Time to play around and see what happens.

Waeco put out an interesting product that could possibly be an alternative solution Waeco Digital SpeedoMetre Head Up Display Hillspeed Up and Down Speed Alert Hud | AutoElec.com.au
I am awaiting a reply regarding suitability for a D2.

Apparently the Waeco unit was produced in Europe for European vehicles....so maybe suitable for the D2?Think I will take the easy way out and go for a GPS speedo with HUD,about $50 on ebay.