Tricking ECU into thinking it is in a certain gear

[takai]

Ok, just been trying to figure out a way around the whole MX83 manual conversion > no cruise control situation, and i think i have sorted a solution. Basically what i was thinking of was rigging up a SPDT relay so that when it gets ACC power it supplies power to the D switch, but when the ACC power is removed it supplies to P or N.

Now, is it as simple as supplying 12v to a certain pin in order to get the ECU to believe it is in that gear? Or does it take something more?

[CrUZida]

2 pole switch on the clutch pedal.

Clutch pedal depressed (down) - NSW activated (ecu thinks in neutral), cruise stops.
Clutch pedal at rest (out) - NSW deactivated (ecu doesnt think its in neutral), DRIVE input on cruise ecu gets signal.

Simple solution.

[takai]

True, that is a whole lot better. Hopefully that way the ECU will let the cruise control work, and i wont have to worry about the whole cruise switches i was going to have to anyway.

[CrUZida]

Oh, and the engine ECU should have nothing to do with the Cruise ECU.

It should be a stand alone unit with inputs/outputs, and its one of these inputs you'll need to trick.

Having never worked on MX83 Cruise I can't say for sure, but I know MX73 and MA61 cruise is completely stand alone (you could convert to carby and it would still work)

[takai]

Ah ok, however, given that the NSW has to interface with the cruise ECU somehow tricking the engine ECU should provide enough information to the cruise ECU in order for it to believe that it works.
Basically i think the problem people have been having (cant be sure, not too many details) is that they are simply hard setting the ECU into N so that they can start and drive the car, and this therefore activates the NSW and disallows cruise.

[CrUZida]

Yes, that is how most do it

http://www.conceptual.net.au/~peewee/wiring/mx83/

You may find the diagrams there.

[JetspeedCamry]

The clutch switch idea was what i was thinking also. At the moment, all ive done is removed the Black wire from the cruise ECU (neutral start wire), so the cruise ecu always thinks its in D. Works well, apart from if you clutch in while cruise is activated, the revs shoot up LOL, so gotta remember to deactivated it/tap the brakes before clutching in.
The thing about the NSW idea, is that whenver i jump the two connections, while in neutral, the revs fluctuate a bit..up and then down, and then stabalizes at a slightly higher idle (800 or so). Not sure how that would effect things when actualy driving/under load.