hello all...

99 montero sport 140k

so...truck would not start, battery dead, replaced battery worked fine all day long then battery showing sighns of not holding a charge. got to looking around and found that the alternator fuse had blown. well, as a temp fix i soldered the broken connection until new one can be obtained. drove about 40 min with lights, stereo, fan on and battery still seems to be holding at 12.4 so im thinking that the alt is charging.


however, the ecu is not keeping any memory...meaning that once the ignition has been turned off, the clock and radio are reset. the clock will remember the time it was when the car was turned off. the stereo will start the cd over again andif left off over a long period of time the radio goes to CODE. also, the dome lights will not work unless the vehicle is running....and when the brake lights are hit the dome lights flicker.

i currently have the neg lead removed from the battery thinking that the ecu might reset itself....im not sure if these vehicles will respond to this or not but giving it a try. all fuses are good under the hood and in the kickpanel.

questions:
any input is appreciated!
where on the alternator can i check the output with a multimeter and what output is norm...14?
will the ecu reset afterX amount of time with the neg cable removed?
is the alt fuse a factory replacement or generic and where can i get one online?
could this be a shart in the battery cables or somewhere else?
where is the ecu on these things?

a lot of question...i know! this is my first post on the board but i am not new to mechanics....just mitsubishis. i appreciate any help on thisand should be able to offer help and input forothers in the future.

 

Good post.

Sounds to me like you know a fair amount and have a decent amount of common sence too. However i DO NOT recomend doing what you did to the fuse. That is potentially dangerous. The fuse should be obtainable any car place. Yes, you also had it correct that dissconnecting the battery will reset the ECU. Maybe that will fix your problem. Remember to put the key in the ignition after you take it off... just to drain any excess power.

From what i can tell you alt is just about fine. The fault might be elseware. I would start by replacing that fuse and seeing if it blows again... if it blows then you have an electrical problem and better start locating it. If the problem keeps up you may need to replace the ECU. It does happen.

Sorry i cannot be any more help than that. I dont actually know where the ECU is on those.

 

OK...reaetting the ecu did nothing! also, add to the list that the "door ajar" beeper does not sound anymore. i tooled around for a while rechecking fuses and testing relays. i have stuck my nose in every cranny sniffing for that burnt wire smell....nothing!

does anyone know if the dome lights and door alarm share a relay or a wiring harness?
i dont have an overhaul manual for this thing yet. however, it looks like i will be acquiring one very soon

 

A manual wont do you ****.

My guess is the ECU. Sounds fried. I would pop it open just to be curious...you might be supprised what you find.

Also, does your car sometimes ... or ever smell of like rotton eggs or any other kind of foul smell for no aparent reason? This could have been your ECU letting go.

I would say that is all that is left to try.

If you want you can go looking around and checking every single wireing harness on the car for any kind of deformaty or malfunction... however that is likely to take a very long time.

My bet is on the ECU

 

Yes the ecu will reset after even a couple minutes but usually to be sure id do it for a 1/2 hour.
Like sebba said the fuse should be generic. Just look at the one that blew. You should have it. It will tell you exactly what amperage you need for replacement.
I have no idea where they put the ecu. Most cars have them under the glove box

 

my opinion its another fuse blown. remember 2 fuse boxes. but fuses are there to protect, if that fuse blew because something shorted sodering it together would allow that surge through the system which a constant surge could easily fry other stuff. in the future probably best to replace a fuse with a fuse

 

Not always true. Fuses constantly have current running through them. Rapid on/off. This causes metal fatigue causing the metal to weaken and sometimes blow. Not caused by any electrical anomily. This in itself can actually cause a power surge.