for the last couple of days i have trying to figure out what is going on with my 98 eclipse. It started 4 days ago with the idiot light coming on and me changing the altinator. After changting the altinator i restarted the car and the light came back on. hooked up my voltage tester to the battery leads and got 18.87 volts (way to much). I changed out the ecu with a used one, new battery, pulled all the minor fuses and cleaned all the connections. same problem over and over 18+ volts. I even had my old altintor and battery checked out and both were fine. When either the + or ecu controlling wires are unplugged from the altinator i get 12.5v at the battery and the charging +/- light is on (I guess no charging). I am at my wits end on this and plan on taking it to shop that deals in car electical porblems friday mourning. if any one has any suggestions i could use them. could a short somewhere be causeing this. i have not done any work on my car for a few months. everyone i know is stumped about this. thanks

98 GS, it's a work in progress. http://monkeywrench.mesanetworks.net

From what you describe, it sounds like there might be a problem with the "Generator Field Coil"--Pin number 8 (blue). This wire or anything in the circuit could be shorted or broken causing the alternator to run full field (overcharging). That's where I'd try next. You said you disconnected the "ECU controlling wires" and the voltage dropped to 12.5, presumably because you were just reading the battery. If there's a problem with the ECU controlling wires, then the alternator won't know when to stop charging. I'm guessing the problem lies somewhere in there. Is there a way you can check the voltage on the ECU wires when they're connected and the car is running/overcharging?

Brian

EDIT: You might also want to check the grounds, or even run dedicated lines, but I'm guessing you might have done that already.

Red 97 Eclipse GS (420a) MTX
Custom Garrett T3 Turbo system
Megasquirt w/52 lb/hr injectors & a Walbro 255
Kicker/Alpine Audio (3 amps, 2 subs)
90 Cav 2.2 TBI auto (winter) <- yeah, it's fast

got my car back today and the electric shop didn't find the problem. He said he could not get a reading on the blue wire that connects to the altinator. I strated to give me some ideas so i started checking around myself with a volt and ohm meter. also looking through the hayes manual the colors seam to be a little off. Coming out of my altinator is a solid blue and red wire (small plastic connection) and the res/black wire for the main screw in type connection. When i hook up all the connection and turn the ignition to on. I connected my volt meter to the red and blue wires on the altinator (unplugged from the altinator). when i connect them to the + side of the altinator i get +12.5 with the red wire (left side of connector) and -12.5 when connected to the blue wire (right side of the connector). I then proceeded to disconnect the battery and ecu to check the pins and ohm resistance (mainly to see if their was a circuit. Hooking the + probe to the red wire and the - probe to different pins in the ecu i got alot of possitive connection in the wireing harness, same with the blue wire. everything seams to be connected correctly with the wiring harness. i then plugged in the wiring harness and hooked up the battery. i still have the altinator disconnected (plastic plug). I then read the voltage coming out of the ecu plug for the blu wire pin 8 (red probe in harness black on the battery). when in the just on posistion engine not running and when the engine is running i get .05 volts when touching groung and .5 volts when touching the + side of the battery. blue wire pin 39 (battery light) gives me 11.5 volts touching ground and 1.6 volts touching +. While view the electric wiring diagram i noticed that the asd relay splices into the altinator red wire. I have spark and she runs smooth. lastly my dad saw a spark near the asd/brake booster area when my computer fried. I am still pushing 18+ volts when everything is hoocked up and running. where should i go from here? I am almost tempted to take my car to satan and have them run a full test. if it explodes under their care they can pay for it. i have run out of ideas?

after finally getting home "my car is parked 40 miles away" i came across an electrical term. their is something called "burned out" and "burned through" burned out meaning no circuit (burned out resister or relay) and burned through meaning a circuit still working but with no resistance (resister burned out but a connection made in its absence). any ideas of this happening to my eclipse?

98 GS, it's a work in progress. http://monkeywrench.mesanetworks.net

so this where i'm at

new battery
old altinator (checked by autozone says it good)
new fuel pump relay
new asd relay
new dis
2 used ecu's

still running 18+ volts at the battery when the car is running. Have checked all the wiring acording to the chiltons manual. Ran the test probe of the ecu harness and everything has power/current/connection. I get .5 volts from the ecu pin 8 what else could i missing that i need to look at? i'm stumped.

98 GS, it's a work in progress. http://monkeywrench.mesanetworks.net

i downloaded the mitsubishi wiring diagram last night and checked my connections. I found no problem in the 8 pin (blue wire) from the ecu to the altinator, no grounding and no power. I found that pin 6 (red wire) from the ecu to pin #2 on the ASD controller does gound using ohm test and grounding point on frame (with battery connected and disconnected). It also shows 12 volts when connected to the + side of the battery but not the - side. un/plugged to the ecu, every fuse/relay pulled from the fuse box except for the two that are screwed in. Pin #2 on the asd relay should only be working if the ecu is plugged in and the key is turned on. i tried splicing in some new wires from asd #2 ecu 6 and new line to the altinator. I forgot that i cut off power to everything else when i did this (spark plugs, cam sensor and what every also makes the engine run). The altenator is good but does not shut off. meaning signal from ecu pin #8 is grounded which it is not. Would grounding the line from asd pin #2 to the junction box in the engine bay cause the porblem of constant over charging? If so how could i test this once my wiring splice is fixed from asd to ecu to altinator. I have been stumped for over a week now and no one can seem to think of anything that could be the cause of my high voltage.

98 GS, it's a work in progress. http://monkeywrench.mesanetworks.net

well after a lot of late nights and searching for answers i have finaaly gotten my car to run the correct voltage. I went through the whole wiring diagram in the mitsubishi repair manual. I fixed all my splicing screw ups, returned all the fuses and put it all back to stock parts. I found that when everything was hooked up i was getting power in my pin 6 to the ecu, this cause power to be distributated to the engine fuse box and all the sendors. When the car is off their should not be any voltage running through this line. only when the key is turned to the acc or starting posistion should power be running through this line. After tearing apart an old ecu and going over to a friends work. This unnamed shop produces circuit boards from scratch. my friend and a circuit board designed looked over my old fried ecu to see what had burned out and why voltage was running on pin 6. What they found i don't really understand but it solved my problem. The ecu requires an internal and external frame ground. The wires running into the ecu have a ground in that cluster and runs what it needs to. But the external frame ground (grounding the external case/heat sinks) is what is used to regulate alternator voltage. so by cleaning off the ecu frame and support structure, grinding any rust off the bolt holes and cleaning out the threads of the eclipse body connection. After doing all this my car went from 19+ volts from the altinator to 13.5 volts. so if you are having high volatge problems first try cleaning the connections to the ecu case and frame support. then check the altinator. hope this helps anyone in the future.

98 GS, it's a work in progress. http://monkeywrench.mesanetworks.net