2G 2GNT Electrical Diagrams

[Dipwhittle]

Hey, for the most part, I’m fine with electrical diagrams… but this has me stumped. I’ve read the how to read the wiring diagram pages so many times and Googled for a while, but I have no idea what this is.

Everything after that point doesn’t work, and the fuse has blown twice. I clearly have a short. I’m trying to diagnose it without disassembling my wiring harness and tracing the wire inch by inch.

Does anyone know what it means when there’s a number circled in the middle of a schematic like the one next to the red arrow in the picture? It looks like a junction. I’m assuming it’s at the interior fuse box under the dash, but what’s the significance of the number? I don’t know for sure what to look for.

You must be logged in to view this image or video.

 

[19Eclipse90]

If you mean physically, I’m not 100% sure a blanket statement could be made to say what exactly the circles indicate.

The manual states the circle…:
“…Indicates harness junction point No. for another system. It corresponds to the junction point No. indicated on the destination system diagram.”

I always used it as another reference point to jog between different systems. For example, consider this image:

You must be logged in to view this image or video.

The 5 circle is highlighted in the Power Distribution diagram. Off to the left, the sub systems are listed. This example I highlighted the Cooling System. Compare to the Cooling System diagram on the right. The 5 circle is highlighted again, as well as the ignition switch and the diagram titles to show the relationship between the power distribution circuit and the cooling circuit.

To better understand your issue, you’re saying you don’t have any power to branch 1? Or to branch 2? Or to either?

You must be logged in to view this image or video.

 

[DreamChaser7]

. Be glad when I understand this stuff too, .

 

[luv2rallye]

Replace the fuse with a small 12v incandescent light bulb. It should go on if there's a short to ground downwind (but the bulb will limit the current draw so you're safe). Then start unplugging everything on that circuit until the light goes out.

Here's a write-up on finding a short - https://www.dsmtuners.com/threads/f...l-short-or-battery-drain.179481/#post-1496998.

If you know the short is in a specific harness or wire somewhere but don't know where along that harness or wire, here is a technique that uses magnetism to locate it: http://www.inliners.org/tech/tech6.html.

 

[Dipwhittle]

If you mean physically, I’m not 100% sure a blanket statement could be made to say what exactly the circles indicate.

The manual states the circle…:
“…Indicates harness junction point No. for another system. It corresponds to the junction point No. indicated on the destination system diagram.”

I always used it as another reference point to jog between different systems. For example, consider this image:

You must be logged in to view this image or video.

The 5 circle is highlighted in the Power Distribution diagram. Off to the left, the sub systems are listed. This example I highlighted the Cooling System. Compare to the Cooling System diagram on the right. The 5 circle is highlighted again, as well as the ignition switch and the diagram titles to show the relationship between the power distribution circuit and the cooling circuit.

To better understand your issue, you’re saying you don’t have any power to branch 1? Or to branch 2? Or to either?

You must be logged in to view this image or video.

It’s both branches. Do you know whether those junction points are physical places you can check or just how the circuit is laid out? I would imagine you could find this physically on the wire, but I have no idea where to look at that. I was hoping this was a reference to a junction that I could look at and pin out.

Replace the fuse with a small 12v incandescent light bulb. It should go on if there's a short to ground downwind (but the bulb will limit the current draw so you're safe). Then start unplugging everything on that circuit until the light goes out.

Here's a write-up on finding a short - https://www.dsmtuners.com/threads/f...l-short-or-battery-drain.179481/#post-1496998.

If you know the short is in a specific harness or wire somewhere but don't know where along that harness or wire, here is a technique that uses magnetism to locate it: http://www.inliners.org/tech/tech6.html.

Super useful! Thank you, I’ll give these a try.

. Be glad when I understand this stuff too, .

Once you understand most of the symbols, it’s pretty easy. I’ve seen much better manuals that give specific page numbers and numbered or colored points or wires that make it easier to trace. They also tend to have a legend that makes the symbols really clear. These manuals are pretty old though, so they’re good for what they are. Just a lot of bouncing around.

 

[19Eclipse90]

It’s both branches. Do you know whether those junction points are physical places you can check or just how the circuit is laid out? I would imagine you could find this physically on the wire, but I have no idea where to look at that. I was hoping this was a reference to a junction that I could look at and pin out.

I’d expect it’s straight out of the fuse at the distribution block - and this is just an easier way of showing it.

I don’t think there is another physical junction point, but I haven’t verified it.

 

[Dipwhittle]

Apparently, it’s multiple shorts in this section. Now the one you labeled 1 works but the one labeled 2 doesn’t… and this isn’t even the only circuit I know I have electrical issues on. MFI has a draw

 

[jed344]

This is not per say a answer but power probe now makes a tool to find breaks or shorts in harnesses. I have not tried it yet but plan to purchase it and test it out as it looks very interesting to save time.

 

[Dipwhittle]

This is not per se an answer but power probe now makes a tool to find breaks or shorts in harnesses. I have not tried it yet but plan to purchase it and test it out as it looks very interesting to save time.

I have something that sends pulses through wires and when you lose the sound, you’ve found your short/break, but it’s pretty cheap. It isn’t very precise.

In other fun news, I fixed my brake lights, but in poking around in the MFI, I now don’t have the 12V to my coils and the car doesn’t start. Can’t figure out how that happened. I’ve checked the connections and everything. When I say this car is a mess, it is a MESS.

 

[Dipwhittle]

Yoooo…. Do I actually have a bad PCM? I’m getting 12V at the cable side input for A107 pin 46, but I’m getting 0V at the PCM side of A106 pins 3 and 11…

For good measure, I also checked pins 6 and 67. They had 0V as well. I ended up checking ALL of the pins on A106. The highest voltage I saw was 0.3V on like half of the pins on the PCM side. I did not have it plugged in, because I avoid back probing when I can. Could that have been the problem for the rest of the pins? Either way, I think I would get voltage to 3 and 11, based on the schematics.

I’m sure this is standard, but my PCM is filled with some type of rubber resin. I can’t check components there.

 

[steve]

Time for a vehicle profile so people don't get confused between 4G63 and 420A when responding. Model year makes a difference too.

 

[Dipwhittle]

Time for a vehicle profile so people don't get confused between 4G63 and 420A when responding. Model year makes a difference too.

99 Eclipse GS, 420A NT

 

[steve]

You can start by creating a vehicle profile for the car here, which will auto-generate a build thread for you and add your car to your signature.

 

[Dipwhittle]

My bad, thought I had already done that, but I guess I hadn’t published it.