Please read!! Possible Ecu problem


Asked by Feb 22, 2016 at 07:55 PM about the 1990 Mitsubishi Eclipse GS 2.0

Question type: Maintenance & Repair

I put a good used alternator on my car and used
the negative terminal test and it worked then after
5 minutes of running with all the accessories on it
died and the alternator was dead. The next day I
bought a new one put it on there and used the
same test. But it ran again without the cable on
there so I thought it was a fluke cause it worked for
3 days. But the other day everything started getting
dim like a bad alt and it ended up dieing. I got the
battery and alt checked they were both fine. My
terminals are clean and look good and so do the
wires could I have fried an Ecu fuse or something
that easy?? I know nothing about Ecu computers.

12 Answers


Honestly what's the actual odds


Did you remove,clean and re attach the negative battery cable from the frame and motor? These cars are known for your kind of issue with these connections not be repaired after years of driving. I feel your ecu is probably ok. That being said the old school way of testing an alternator by removing a battery cable is very dangerous on newer cars. If can fry electronics. But normally if this happens the car would not crank at all even with a good battery.

Best Answer

Ohhh I see. And what does the one that goes to the motor look like. Is it a bolt or is it like a plug. And how would I go about getting it cleaned cause the line runs down under dome stuff. But it's really black and sludge down there.


It should be a bolt thru a ring lug on the cable. Follow cable from battery and you will find both. Just remove the bolts and wire brush the ring lugs and the surface it hooks to on the frame and motor. Remember to unhook both battery connections before you start, also inspect the cables at the battery. If there is any frayed wires sticking out then also repair these too


The ground connected to the motor is in a really bad spot. I don't know what to take off to get to Ithe it's uner the ecI multi thing where the throttle is down under all that.

1 of 1 people found this helpful.

So whats the easiest thing to disconnect to get to the ground on the motor


Not sure in your case without looking at it. Long extensions may help you get a socket on it.


Can a faulty fuel injector do the same thing? Because my lights started getting dimmer and dimmer and when I try to accelerate over 10mph it would start to stall. Can it be a eci relay?


Lights getting dimmer leads me to believe that it's in your charging system. Nothing much else would cause your battery to go dead. If alternator and battery are new then I would clean all connections.


Ok charge battery then do this test. With car running use a multi meter and check voltage at the battery. You should have 14.5 volts with car running. If you do and battery still going dead while driving then it's battery cable connection issues either on positive side or whole negative cable side(battery,frame or motor)If you have less than that then check from positive of battery to any metal on the motor. If you have 14.5 or so volts now then it's a negative cable connection issue. If you have less now test the alternator straight to the motor. If you have 14.5 or so volts now then it's a connection issue in the harness from alternator to battery or positive battery connection issue.


The car wouldnt run. After the night I couldn't get it to start anymore I took the alt and the battery in and they were fine. Car isn't back together yet because I don't want to put the alternator in and put it in wrong.


And I'm visually checking other things. I don't have anything to test connections with

Your Answer

Add photo

Related Questions

  • Please read!! Possible Ecu problem 12 answers

    I put a good used alternator on my car and used the negative terminal test and it worked then after 5 minutes of running with all the accessories on it died and the alternator was dead. The next da...

    1990 Mitsubishi Eclipse GS 2.0


    Maintenance & Repair

  • ecu 2 answers

    Can I replace my ecu (not the relay but actual "brain" with a previously used one? And if so is there a proceedure or steps necessary to do so?

    2000 Mitsubishi Eclipse GS


    Maintenance & Repair

  • ers acceleration problem 1 answer

    ok so I just got my transmission rebuilt in my 96 ers its a automatic trans. 420a and I got maby 5 miles from the shop and the motor started to not accelerate properly and also it now sounds like a v8...

    1996 Mitsubishi Eclipse


    Maintenance & Repair

  • Transmission Relay on 1999 Eclipse? Please help? 3 answers

    My 1999 Eclipse's check engine light has been on for a while and the car sometimes will not change gears right in the middle of driving but if you turn it off for like 15 mins its fine. We ordered tra...

    1999 Mitsubishi Eclipse GS


    Maintenance & Repair

  • RPM problem on right hand turns only 5 answers

    I have a problem when accelerating around right hand turns only. The rpms with start to (i dont know how to describe it so bear with me) rise and lower repeatedly until i straighten out. It does not ...

    1999 Mitsubishi Eclipse RS


    Maintenance & Repair


Looking for a Used Eclipse in your area?

CarGurus has 1,319 nationwide Eclipse listings starting at $1,990.


Search Mitsubishi Eclipse Questions

Mitsubishi Eclipse Experts

#1 dandyoun
Reputation 1,630
#2 Daniel Foster
Daniel Foster
Reputation 730
#3 Tom Demyan
Tom Demyan
Reputation 420
View All

Related Models For Sale

Used Ford Mustang
692 Great Deals out of 44,319 listings starting at $1,500
Used Honda Civic
843 Great Deals out of 83,685 listings starting at $1,200
Used Chevrolet Camaro
377 Great Deals out of 31,274 listings starting at $2,500
Used Mitsubishi 3000GT
81 listings starting at $2,999
Used Chevrolet Corvette
230 Great Deals out of 22,185 listings starting at $3,750
Used Toyota Celica
328 listings starting at $2,700

Used Cars For Sale

2012 Mitsubishi Eclipse For Sale
6 Great Deals out of 58 listings starting at $5,990
2011 Mitsubishi Eclipse For Sale
52 listings starting at $3,995
2009 Mitsubishi Eclipse For Sale
5 Great Deals out of 147 listings starting at $3,400
2008 Mitsubishi Eclipse For Sale
3 Great Deals out of 187 listings starting at $2,999

Content submitted by Users is not endorsed by CarGurus, does not express the opinions of CarGurus, and should not be considered reviewed, screened, or approved by CarGurus. Please refer to CarGurus Terms of Use.