Megasquirt/7AGE/Custom harness questions (Wiring Guru help!)

[c4ptiv3]

Just traced both harnesses I have and the ground is cut on both coming off the TPS...

[jondee86]

Do these tie in through the ECU or what?

Mine is not to try and understand the workings of the inscrutable Oriental mind
I restrict myself to studying the ancient diagrams and scripts to divine in which
directions the ineffably small electrons might be flowing. And in this case I have
discovered that...

THW sensor ground ==> C*10 ==> E21/R12
TPS sensor ground ==> C*10 ==> E21/R12
AFM sensor ground ==> C*10 ==> E21/R12
THA sensor signal ==> C*1 ==> THA/R3
THW sensor signal ==> THW/S10

Which says to me that the sensor ground wires must be spliced together before
they get to the C* plug. It also appears that all the AFM wires must get bundled
together and brought into the car before feeding back to the ECU via the C* plug.

Can't comment on cut ground wires other than the fact that there is usually a
ground wire from the AFM for the switch that controls the COR/FP circuit. This
is a chassis ground and separate from the sensor grounds.

Cheers... jondee86

[c4ptiv3]

Okay, but that doesn't answer my question lol.

The A plug from the ECU is for the body harness. Neither of the two harnesses I have connected to that plug at all for the E2 pinout. Do these come in contact with each other behind the scenes (Best analogy I could think of for correct wording) or what?

In all the wiring diagrams I have for the factory harness it shows them connecting to each other, however, there is no way this is possible or you would not be able to remove the engine harness from the car without cutting something. I'm assuming that they are soldered together elsewhere in the body harness off the C* plug somehow. Would you agree?

[c4ptiv3]

Should I just forget about the E2 being spliced in since it is part of the body harness I did not touch and just splice the rest of the grounds in as normal? Since I didn't mess with it I'm assuming that it's good to go.

[jondee86]

Yeah... I dug down through the various strata of debris thay fills my shed
and found a complete JDM (MAP) engine harness. The THA sensor definitely
wires into the engine harness on the MAP version, and E2 is in there also.
So both of these make it to the ECU.

I know when I reworked a harness for my car I did not mess with the C* plug
although I did a bit of testing to see what functions the pins performed. So
I guess there are some differences between JDM and USDM harnesses, and
what you need to do is simply check that each sensor has a circuit... an
individual input to the ECU and a connection to an available ECU ground. My
guess would be that the C*1 THA pin got bypassed and that the THA connects
directly to the ECU and is linked to E2 somewhere in the engine harness.

You can check that

Cheers... jondee86

[c4ptiv3]

FINISHED!!!!! Thank you so much for the help Jondee86, this is an amazing accomplishment for me.

http://i.imgur.com/xXY37Or.jpg


and I was correct, the E2 and THA wires join up behind the PCB/Junctions in the kick panel.

[jondee86]

Congratulations... now the next one you do will be a lot easier

Cheers... jondee86

[c4ptiv3]

Got the harness installed finally, here's a pic for everyone that helped (Sorry it's a bit blurry). I just need to tidy up the wires some once I get some clips to hide them better. Looks much better than it did before. Hopefully I'll find out if it works tomorrow.

http://i.imgur.com/cMdd0di.jpg

[jondee86]

Some good work there I'm sure it will run just fine !!

Cheers... jondee86

[SgtRauksauff]

nice! just sort of watching and paying attention if I ever need to do some aftermarket ECU tomfoolery.

I've seen other cars that have chassis ground as the sensor ground as well, most of them in fact. A friend was having an issue getting his twin-M90-LSx to run using a DIYPNP, so I looked it over for him... once I re-did the harness to get all the sensor grounds together, and ran the one wire from them to the ecu, we got excited, because it fired right up.

This was awhile ago, so it's not fresh in my mind anymore, but I remember looking over his harness, and reading the diypnp manual, and then the big lightbulb flash over my head, and 20 minutes later we fired up!

https://youtu.be/T_nPPh_6H_4

[c4ptiv3]

Just gonna leave this here.

https://www.youtube.com/watch?v=qTLkx8I3LK4

[jondee86]

Good work there... very tidy installation !!

What cams are you running... sounds mean

Cheers... jondee86

[c4ptiv3]

Running some TRD 272 cams and thank you! I was really worried about the harness not working.

I'll post up the latest revision of the wiring diagram if anyone plans on going this route in the future, I've done all the hard work for you all you have to do is run the wire.

[c4ptiv3]

Here is the wiring diagram. I was using the sequential injection add-on for the MS unit hence injectors 3 and 4 going to the DB15 connector. If you have High Impedance injectors you can just tie them together like in previous diagram in this thread.

Keep in mind you can use your own colors, that's just what I used. You can get 13 single color wires from Maneywire for 78 bucks @ 100ft per color.


LEGEND
C Plug - This is the plug that sits on the firewall in your engine bay.

C* Plug - This is the plug on the engine harness that plugs into the kick panel rather than the ECU. (So where it shows Pin 1 and Pin 10 going to THA and E2 it is already tied in behind that PCB board in the kick panel, you don't have to add it in.)

http://i.imgur.com/lvRiODE.png