Detailed wiring diagram for relays and engine bay/interior fuses?

BANGINBISHI

MEMBER
2003 MITSUBISHI GALANT
2.4L
4 CYL
FWD
AUTOMATIC
285,000 MILES

I've been doing some hardcore Googling for almost a week now on top of using my Haynes manual and can still only piece about 40-50% of this wiring together.

Parts Affected:

A-18x MFI Relay (Reading a crazy fluctuating ground between 40-60ohm)
A-19x AC Compressor Relay (Same as MFI relay)
A-17x A/T Control Relay (Getting hot)

A-09x Fan Control Relay (Getting Hot)

Under Hood Fuses #9 (ECU) and #15 (A/T)

Interior Fuse #13 (ECU) [Reading a ground at it at 50ohm]

Getting a lot of audible electrical interference coming from the A/T control unit itself when its harness is plugged in. (Though unplugging it doesn't change any warning lights or the weird readings from the relays)

So far I've gotten the wiring for MFI Relay to Fan Control Relay, To PCM and a couple other small things. I have more detailed diagrams, but they're off-yea, r so I'm not sure if I can trust them completely.

Does anyone know where I should check for a failure first? Is there anything that's a common weak-spot? Also, all of this is possibly due to a sudden jump in amperage going through the system.

I've eyeballed a few plugs related to the circuit and checked the relay pins, nothing is looking burnt/bare so far.

7 Replies

KEN L

MASTER CERTIFIED MECHANIC
47,526 POSTS

Please try unplugging all alternator wires, please don't let them touch ground, I'm thinking it could be internally shorted.

Also check the battery ground (to frame and from engine) and power cables for corrosion and lose connections.

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Monday, March 14th, 2016 AT 12:50 PM

KEN L

MASTER CERTIFIED MECHANIC
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I forgot the wiring diagrams, let me know what you find.

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Monday, March 14th, 2016 AT 4:17 PM

BANGINBISHI

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5 POSTS

Should have noted that I've already had the alternator tested at O'Reillys and re-checked the ohm readings and system before hooking anything back up. Everything was the same.

I cleaned up my stock ground and installed two more a few months ago. All three are solid, but I will go through them individually here in a minute minute.

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Monday, March 14th, 2016 AT 4:18 PM

BANGINBISHI

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Ah! Thank you! Just noticed the diagrams. I'll do some scribbling and mapping tonight and check them out tomorrow.

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Monday, March 14th, 2016 AT 4:20 PM

BANGINBISHI

MEMBER
5 POSTS

Checked the grounds independently. Same thing.

Some extra information that I didn't want to include in the bare-bones, advanced information version of the question.

The car completely shut off while running, reset, and read off Brake and Oil lights.

Everything interior works, it cranks but it's obviously not getting fuel and I'm 80% sure I'm not getting spark either.

As far as the amperage dump being the cause theory goes it's because I was getting some audio interference in the two turns before it shut down. When I popped the hood I noticed my secondary alternator to positive cable had come loose (though it doesn't look like it had a chance to short anywhere.) Should have use a lug instead of trusting the terminal clamp.

Also, when checking the alternator I'd noticed part of the plastic on the casing had cracked, causing the stock alt-positive ring terminal to sit a bit loose. So unless it's crazy happenstance it was a sudden large boost in amperage through an already loose connection that caused it.

Both batteries also tested as healthy. (Only running one with no aftermarket cables connected for all my testing.)

No aftermarket cable to the alternator either and the stock connection has been shored up.