Time to replace alternator or wiring problem?

Question

I was driving on the highway and the battery light came on. Then I was sitting in traffic and the Jeep just stalled. I restarted and could only keep running if I gave it gas. The check engine light came on. Went back on highway and got home.

The MIL is 12 (battery disconnect) & 25 (idle air control motor circuit). The battery still has almost 13 volts.

Id this a wire or short or is the alternator going/gone?

DougW · Accepted Answer

Clean the idle air passage. It's gummed up.

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You don't need to take the TB off, just clean the top and bottom of the valve with a toothbrush and some carb cleaner. Then go around the bore. Next with the engine running, spray cleaner into the passage just above the valve. Try to keep the engine running. If things are real bad you might have to take the idle motor and valve assembly off and clean it on the bench. NOTE: Never run the engine with the idle air motor dissembled, the idle air motor/solenoid will be damaged.

DougW · Answer

oh.. and as for the battery, check and clean the terminals. Usually, but not always, when they get loose all sorts of codes can be set. Code 12 just means the battery was disconnected within

50 startups.

Mindy · Answer

I agree ... man knows what he's talking about ... same problem, same solution .. easy job

Will Honea · Answer

Another odd problem can be with the inline fuse wire. Mine started throwing battery/alternator codes and it turned out that the fuse wire was corroded and broken where it was crimped to the alternator output wire. The problem was erratic and getting worse but it took forever to locate the problem.

csdude · Answer

I would take the throttle body off though, that way you can take theidle control valve/plunger/motor off and really clean the passages,butterfly and walls and the idle control motor itself. If it says theidle control motor circuit isn't working the idle control motor iseither dead or can't move or so. I have seen some gunk in my old grandcausing the same problems (I ended up getting a new idle controlmotor). Taking the throttle body is pretty easy, the gasket doesn'teven cost a buck and that way the crap you wash out doesn't end up inyour intake manifold.

Mel P. · Answer

Doug,I understand code 12 and have gotten it before  on several occasions for different reasons.  But my battery light came on.  Should I be concerned about my alternator?  Maybe the voltage regulator?thanks again,

DougW · Answer

Could be the battery.If it was the alternator there would be other codes thrown.That and I've got a 93 ZJ with the original alternator so theydo last quite a long time.I've slept since yesterday, what is the year/model of your jeep?These come in handy. URL, but there are several three LED versions of the same thingthat help diagnose low/high charge and low/high capacity.

Time to replace alternator or wiring problem?

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