Resolved 2G Over charging alternator?

[Bedicine]

Hoping someone would be able to chime in on some issues I’m having.

Car was having issues the other day when I turned on the high beams that all of the lights went out and car started idle surging. We remove the alternator and tested the battery. Battery is brand new and no issues shown on the tester.

Alternator was fried, new 90amp alternator ordered and installed, car fires up no problem but still getting an idle surge and voltage jumping to 17. I’ve attached a video for reference at idle. Battery light is also still flashing.

Alternator relay was also replaced, starter is sometimes clicking and it’s new (wondering starter relay) but could this be a symptom of a burnt spot on my ECU causing the voltage to spike and battery light not going off?

When the voltage spikes the rpm’s are also raising up to 1700, when it drops back down the car idles fine

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[dwb]

Sounds like you got a DOA alternator due to voltage regulator malfunction.

 

[Bedicine]

Sounds like you got a DOA alternator due to voltage regulator malfunction.

Could it be the ECU at all? Weird the battery light is still flickering

 

[dwb]

could it be the ecu at all? Weird the battery light is still flickering

Failed alternators make the dash lights do strange things.

 

[Bedicine]

If I was to pull the ECU which I believe pin 33 is what sends the output signal to the alternator would I be able to visually see anything?

A lot quicker to pull the ECU then take the alternator back off

 

[dwb]

Some good info in this thread regarding the trigger wire (#33), although this is talking about 97+ 2g: https://www.dsmtuners.com/threads/alternator-trigger-wire.520037/
However I don't think any component other than a bad voltage regulator can cause overcharging.

 

[steve]

However I don't think any component other than a bad voltage regulator can cause overcharging.

Sure sounds like a dud alternator to me too.

 

[Bedicine]

Third alternator tonight and putting a volt meter right to the alternator power wire we’re seeing spikes of up to 21. Battery light is off, what are the odds it’s 3 bad ones now and not something else in the car?

 

[Stapl3]

I've been trough this. Find a good, oldschool alternator place and take it there.

 

[Bedicine]

Trying that Tuesday. The one tonight was making a loud noise, it’s insane how bad these are out of the box

 

[luv2rallye]

Do you have the alt's Sense red wire (pin 2 of the 4 pin connector A-03 on the alt) connected directly and only to battery positive? If not the alt output voltage will go all over.

 

[Bedicine]

Do you have the alt's Sense red wire (pin 2 of the 4 pin connector A-03 on the alt) connected directly and only to battery positive? If not the alt output voltage will go all over.

You mean the alternator would have the battery connection, ground (through block) and then pin 2 just going to battery, rest of connector not unplugged? A volt meter just off the connection should show below 15 without any other connections based on its own regulators though?

Right now the current alternator was making a loud noise and sitting in the lower 11s for voltage to the car which we witnessed on a gauge and through link

 

[luv2rallye]

Well in post #1 you said you put in a 90A alt. Stock turbo alt is 75A and specially made for the Mitsubishi turbo with that A-03 four pin connector so the ECU can control certain things in the alt (like loading and idle speed). So I don't know if your 90A alt even has the 4 pin connector or it's functionality. Typically after market 90A alt's don't, since they are made for multiple vehicles. But even if it doesn't, you still have to have your alt's "S" terminal go directly to the battery positive on it's own separate wire (it can't go anywhere else or share with anything else - this is crucial). The alt will adjust it's output voltage to make whatever the "S" wire is connected to be 14.4V nominal (which is what you nominally want on battery positive).

 

[Bedicine]

Well in post #1 you said you put in a 90A alt. Stock turbo alt is 75A and specially made for the Mitsubishi turbo with that A-03 four pin connector so the ECU can control certain things in the alt (like loading and idle speed). So I don't know if your 90A alt even has the 4 pin connector or it's functionality. Typically after market 90A alt's don't, since they are made for multiple vehicles. But even if it doesn't, you still have to have your alt's "S" terminal go directly to the battery positive on it's own separate wire (it can't go anywhere else or share with anything else - this is crucial). The alt will adjust it's output voltage to make whatever the "S" wire is connected to be 14.4V nominal (which is what you nominally want on battery positive).

The alternator I have (90 amp) has the connector, it’s made for the car. I have a 4 gauge wire running directly from the battery (trunk relocated) to a fuse then to the positive terminal on the alternator. I have a brand new relay that the blue wires feed to I believe for the battery light and then the connector is plugged into the alternator.

The ground is just off of the bolt that holds the alternator and grounds off the block. I had a seperate ground connected in addition but it didn’t do anything else.

The S wire you’re referring to isn’t that part of the connector already?

 

[luv2rallye]

Yes the alt's "S" (sense) terminal is connector A-03 pin 2 (red).
Remember the alt will adjust it's output voltage to make whatever the "S" wire is connected to be 14.4V nominal (which is what you nominally want on battery positive). So with your battery in the trunk, if you want 14.4V on it you have to have a separate dedicated sense wire (this cannot be shared with anything or going anywhere else which would create an unwanted an voltage drop in it) going from the alt "S" terminal {A-03 pin 2 (red)} all the way to battery positive. There's almost no current in it so a small wire is fine (just rugged enough to withstand the elements).

Just FYI: The alt "L" terminal "Lamp" (A-03 pin 3 blue wire) goes to both the battery light and the generator relay. The generator relay is just a backup should the battery light not work to provide voltage to the alt's field coil which is necessary for the alt to work.

 

[Bedicine]

The existing s wire where would that have been going to the battery in the engine bay and if so what would it look like? I don’t remember seeing any wires just hanging from when I relocated the battery

 

[luv2rallye]

I no longer have my Eclipse to look but the diagrams show a red flexible 14 AWG (2 square mm) wire going to the 40A fusible link "headlamp" fuse in the engine fusebox.

 

[jed344]

I am going to assume the 90 amp alternator is the auto non turbo gallant one? Early 90's as i recall for the years. That is a direct plug and play replacement that works as we have used those for likely close to 10 years now, if it is some other kind of alternator then i have no info that would be useful.

 

[Bedicine]

Doesn’t seem to be. Rock auto lists it for the 2g. Identical shape and size to the oem one with the same connector.

Cut the red wire at the alternator tonight, connected it to a new line that runs to a 2.5amp fuse in the trunk and then to the battery positive. Idle surge seems to be gone and it turns off the battery light. Alternator is still overcharging, going to try another one tomorrow now that we have the s wire connected

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[chrisman287]

I had a WAI that I bought off someone local that was new and ended up being DOA. Tossed it and went used 2g OEM.

I am considering finding a used Galant OEM since I noticed battery voltage dropping to 12.7 when giving it the beans.

 

[jed344]

Doesn’t seem to be. Rock auto lists it for the 2g. Identical shape and size to the oem one with the same connector.

Cut the red wire at the alternator tonight, connected it to a new line that runs to a 2.5amp fuse in the trunk and then to the battery positive. Idle surge seems to be gone and it turns off the battery light. Alternator is still overcharging, going to try another one tomorrow now that we have the s wire connected

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I have never used that one. We always used i think it was a 92 or 93 auto non turbo galant alternator. Direct plug and play and 90 amp.

 

[Bedicine]

Sense wire connected straight to battery, new alternator on and battery light is still coming on. Car is hesitating now and voltage dropping to 11.2. Any ideas?

 

[Bedicine]

I have a 4 gauge lower wire running straight from the trunk battery to a fuse by the fuse box which connects to the original w white wires that go to the positive on the alternator. Could those two wires maybe causing the issue or is it possible the ecu is damaged?

Driving the car it also felt very sluggish with the battery light coming on and idle jumping
I also only the battery ground to the frame in the trunk, not sure if a separate ground from the trunk battery to the engine block itself would change anything

 

[Bedicine]

Sent the ecu out to be checked and it seems fine. Not sure what else to check at this point?

 

[dwb]

I also only the battery ground to the frame in the trunk, not sure if a separate ground from the trunk battery to the engine block itself would change anything

Do you at least have a ground from the chassis to the engine block?