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Fuel cut signal, where does ECU get it from?

oxford1327
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oxford1327 Experienced

oxford1327

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Wondering if the brains trust can shed some light on where the ECU gets its signal to trigger the fuel cut at 180k?

Does it originate from the dash cluster or from the ECU itself?

Car in question is a series 2 Stagea and currently have a pivot speed meter installed, but have also fitted a Link Strada dash and Storm-X ECU which has rendered the speed readout on the pivot meter defunct and not displaying anything, so I dunno if the fuel cut bit is still functional until I either find a quiet road or get it on a Dyno, if it is not required anymore to provide fuel cut get-around I'll pull it out along with the also now redundant boost controller and sell them both. 

Hopefully someone can share the knowledge.....

GTSBoy Grand Master

GTSBoy

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Speedo head generates PWM square wave speed signal that is transmitted to every CU in the car that wants a speed signal (ie, HICAS, TCS, ABS, ECU, TCU). The ECU just waits until it sees 180km/h then calls a halt to proceedings (as well as using a threshold at about 5 km/h for idle up and similar drivability features).

If you have removed the speedo head (ie the whole cluster) then you have no speed signal - unless that is, if the person who installed the Link dash put the required effort in to connect the speed sensor** (on the gearbox) to the dash and have the dash output a suitable equivalent PWM signal as the original dash would have.

**which is an AC sawtooth signal because of the reluctor sensor.

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oxford1327 Experienced

oxford1327

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6 hours ago, GTSBoy said:

Speedo head generates PWM square wave speed signal that is transmitted to every CU in the car that wants a speed signal (ie, HICAS, TCS, ABS, ECU, TCU). The ECU just waits until it sees 180km/h then calls a halt to proceedings (as well as using a threshold at about 5 km/h for idle up and similar drivability features).

If you have removed the speedo head (ie the whole cluster) then you have no speed signal - unless that is, if the person who installed the Link dash put the required effort in to connect the speed sensor** (on the gearbox) to the dash and have the dash output a suitable equivalent PWM signal as the original dash would have.

**which is an AC sawtooth signal because of the reluctor sensor.

Awesome, thanking you very much for perfectly detailed reply, now to start removing redundant displays and declutter of dash area 

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