Chip question

[LightningGSX]

The park-neutral input(clutch input) into the ECU is a high impedance input with an internal pullup resistor to power, meaning it rests at a logic 1(on) and it takes very little current to switch from 1 to 0 or vice versa.When the clutch switch is activated(clutch depressed) it grounds(logic 0) its signal output.Without the diodes, even when the clutch is pressed, and it grounds its signal wire, there will still be a logic 1 at the ECU input due to power through the starter relay coil.So essentially the 12v power applied to one side of the relays' coil, drowns out the ground signal from the clutch switch.If you take a high impedance test light and probe your added clutch wire, you'll see exactly what I'm talking about.

[Wizard]

Well, anyone have any part numbers for me then? This ECU was installed by a certain shop and they never hooked up the clutch switch. So I have no diode-equipped clutch wire. Or would just any 12-14v diode work as long as it's hooked up correctly? Better yet, how about a wiring schematic? I have the factory manuals, BTW.

Thanks,

Wiz

[LightningGSX]

You need 2 1N4001.They're very common and should be easy to find.There's a silver band on one end.Connect the 2 banded ends to the clutch switch, the other ends go 1 to the ECU and 1 to the starter circuit

[Wizard]

Cool....thanks. Another thing......who's got a 1g ECU that works? Turbo of course. Found out that one of my projects has a dying ECU. Only thing I got is a 2g Turbo w/harness and 92 NT ECU. I know the NT will run the car but at a lower performance level. The 2g will work great once you get the 100+ wires soldered together. Really just looking for a good 1g 91-94 (don't feel like switching any wires) Turbo ECU.

Thanks,

Wiz

[LightningGSX]

If you can't find the diodes, I have over a thousand of them, they're only a few pennies a piece so I could drop a couple in the mail.

I would just try to find an ECU in a local junkyard, if that doesn't work out I have like 12-13 of them

[Wizard]

Local J-yard in Aberdeen? There are only 2 (Yes only 2) DSMs in the j-yards here. One is a wrecked 2.0L NT (1990) that we just bought for a bottle of whiskey and a 1.8L NT that was also wrecked. That's it.

We are running the NT ECU for now until we find one. Thanks.

Wiz

[LightningGSX]

You could also transplant a few parts from the dying ECU into the NT ECU to make it a turbo ECU. Knock board, flyback caps, etc.Very easy if you're familiar with that kind of stuff.

[Wizard]

Not worth the trouble to mess with it. Especially when a good turbo ECU was found locally for next to nothing.....will be upgrading the caps before anything goes bad on this one.

Wiz