Wiring Harnesses: DIYAutoTune vs. Megamanual

[chsmadden]

I went to DIYAutoTune and picked up one of their premade 8' wiring harnesses, and when I was mapping it out and bundling wires together (injectors, sensors, etc), I noticed that there are some stiking differences between the diagram provided with the premade and the diagram on the megamanual.
Pins 15-19 are ground on the premade and pin 6 is a dedicated sensor return wire. In the megamanual, pin 19 is the sensor ground and 8-11 and 18 are system ground.
Everything else is fairly consistent except for the hall sensor/ignition input where 1 and 24 are a twisted wire with a sheath which has been connected to pin 2. The megamanual dictates that pins 2 and 24 should be a twisted pair of wires with no indication of a sheath. The last thing I want to do right now is flick on the key and see my new MS2 leak it's precious smoke.

One final question, I plan to draw a tach signal from the negative terminal of the coil, which wire would be used for this? The diagram listed in the megamanual lists underneath it "Tach/Crank Position Input (Hall/VR/Coil-)," and the supplied diagram lists nothing of the sort, only Hall or VR and wires leading to them.

[trakkies]

Interesting point. I've noted the difference on pre-made tails from the MS diagram. Of course 1-2 and 7-19 all are connected to the ground plain within the board, so I'm not sure if it matters too much. But it is important to ground all the sensors at the same point. (Or rather, that's the correct way of doing things in theory - so that's what I did here)

Pin 24 is simply linked by a track to TachSel. When taking the tach feed from the coil you'd normally not need any screen on this due to the relatively high voltage, so ignore the other wire of the twisted pair and the screen. Either disconnect at the D37 or make sure they can't short to anything. And follow the instructions for direct connection to the coil.

[Bernard Fife]

Guys,

All those top row of ground pins (1, 2, 7 - 19) connect to the same ground location on the PCB. So there's no real difference in swapping any of those pins around, and that's what DIYAutoTune has done.

The 'sensor ground' isn't a special location on the PCB; it is just that the sensors should have a separate ground wire (i.e. not the power or injector/ignition grounds) running to the controller to reduce noise.

Both ways work fine, and it isn't 'wrong' either way.

Lance.