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See if this helps. It's from the 1990 manual.

Thanks for the responses guys.

It doesn't heat up when its in the "on" position. Only when the motor is running. I swapped out another used ignition from the junk yard and it does the same thing. Makes me think its further down the line. I pulled the electrical diagram, but im not electrical magician. The circuit is the yellow highlighted area.




New ignition. It overheating wire is the bottom one thats all black.




I went on to trace it back into the "fusible link" box that is on the inside fender. I didn't get a photo, but it looks like this:




This wire also gets warm and the color on it looks like its seen some heat, but nowhere near melting like the connector under the dash.


Now my weird brain thought my batteries ground was bad, so i started cleaning contacts, but the same problem still persists.


What do the BAWC pros suggest?

You've added a lot of electrical load that this truck wasn't designed with. The engine has sensors and solenoids the original didn't. We know for sure those MIVEC solenoids pull some serious current. Might need to look at adding a relay and some beefier wiring.

Hmm. Its been doing so well for years, I would have thought something would have poked its head early on if it was an issue. Do you think a bad coil, or alternator would cause this?

Where would you recommend adding the relay?

Remind me again which ECU you have in this thing? Do you have an upgraded fuel pump?

Do you have access to a clamp style current meter that can do DC?

I have a 98 SL ECU running it IIRC. Fuel pump is a knock off Walbro 255. I have a standard volt meter that can read AC/DC, Ohms, Amps, etc.

I need to trace out that clusterfuck of a diagram a little better, but here are my current ( ) thoughts for now.

4G Eclipse has a 20 amp circuit for the MFI system, 10 amps for the 6 ignition coils (coil on plug is more efficient), a 15 amp circuit for the fuel pump, and a bunch of other fused circuits for everything else in the car.

3S is 20, 15 and 15.

You've basically got a 20 amp circuit for the MFI and a 60 amp circuit for virtually everything else on the truck, including the fuel pump.

What's powering the window switch for the MIVEC solenoids? Maybe try shutting that off and do some driving tests without the solenoids powered.

Yea, that diagram isn't the easiest. Bit of a shock...

I'm no longer running COP. I have the 3 Montero (similar to 3S) coils with wasted spark. Fuel pump is running on stock wiring.

The ignition heats up just idling with no actuation of the MIVEC solenoids. I cant recall where I'm pulling power for the window switch. Likely from an existing power line. Id need to check.

It's good that it happens at idle. That'll make it a lot easier to test.

I'm also wondering if it's not just an under sized ground somewhere. Gotta nail down which circuit is causing the problem first.

Well that's a good sign i guess. I've been contemplating the ground as well. I cleaned one contact that was a little corroded by water. I like to frequently clean out the engine bay. I can go through and make sure all are good. I did take another very large ground wire from the post to the body when it was overheating and no change though.

Should i grab the DC current tester? Will that make this easier to diagnose?