Help! Electrical problems, need to know whats wrong asap!

swiftstar

New member
So a few months back I had to replace the spark plugs on my 98 montero, and I did so successfully (a much more difficult feat than with most cars and trucks), but a little while after that, I noticed that the engine would idle pretty rough and, after a few months, the check engine light came on. I checked out why, and it ended up being a misfire in cylinder 1 (no other cylinders), and since I had just replaced the spark plugs and the fuel filter was around 120k miles old, I figured that was it, and replaced it. The rough idle was still present after the repair. And after a couple of weeks from there, the check engine light came back on for the same reason, and I looked into it and figured that it was probably an ignition coil. I had checked the voltage of the alternator with the car on and off (13 off and 14.5 on), so I figured the alternator wasn't going bad. So the ignition coil is on its way, but just today I was driving and I noticed that the dashboard lights were getting really dim, and then the anti lock brake light came on, and then when I turned off the ignition key and tried to turn it back on, the battery was dead and wouldn't start. So I waited a few minutes and the car started again, but the dash lights were still dim and the anti lock light still on. Then as I was driving with my headlights on, the srs light came on, which was quite worrisome, and the speedometer started going crazy. But once I turned the headlights off, the srs light turned off and the speedometer went back to normal. And after that I drove home and turned her off. It seems like an alternator problem, however I just checked and the voltage was normal, so I'm going to jump my car tomorrow and see if it helps (I don't have a charger), but I wanted to know what you guys think, since some more experienced advise would be greatly appreciated. Oh and I'm not sure if this is related, but before this happened, at random times my brake, battery and a/t light would all come on at the same time for a few minutes, and then shut off for a while. Thank you!
 

SoCal Tom

Explorer
How old is the battery? Check the voltage in the morning before you start the car. What is it? Then turn on the headlights and check voltage ( without starting the engine). The start it and repeat those tests. Post a picture of the battery terminals.


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jlocster

Explorer
Battery, A/T, and brake lights illuminating is consistent with alternator trouble. Also, if you replace your Mitsubishi alternator with a generic alternator, you can expect the battery, A/T and brake lights to continue to illuminate at low engine RPM, even if the alternator is charging properly.
 

swiftstar

New member
The battery is pretty new, I bought a brand new one for the truck when I got it. The voltage was 11.5, with the headlights on it dropped to 8.5. It won't start but I've got a friend coming to jump it for me again and I'll text it then. And I'll get that picture posted asap
 

haolepinoy

Incomplete Idiot
The battery is pretty new, I bought a brand new one for the truck when I got it. The voltage was 11.5, with the headlights on it dropped to 8.5. It won't start but I've got a friend coming to jump it for me again and I'll text it then. And I'll get that picture posted asap

At 11.5v your battery is practically dead (at 12.0v a car battery is at around 25% charge). Either your alternator is not charging it (bad alternator or connection)...or the battery is not accepting a charge (bad battery or connection).
 

SoCal Tom

Explorer
The battery is not charging, this can be bad alternator, bad battery, dirty connections, worn out cables. Put the battery on a charger and see if it takes a charge. Clean all the battery terminals. If you are getting over 13 volts with the engine running then the alternator is charging.


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