alternator question.

hey guys, I've got a problem and need a little help. A few weeks ago I went on little trail ride. About halfway or so My alt started to die. By the end it was only putting out about 9 volts according to the gauge. When I started to pull out onto the main road my trans wouldn't shift into first. It stayed in high gear. I nursed it home and figured I take care of it later. The next day it started and charged just fine and the trans shifted like normal. It lost charge like this before but the trans never did this before. I'm wondering if I just replace the alt with a new grand cherokee high amp version or is something else going on?

The computers don't like low voltage. They do weird things as you saw with your transmission. if you are replacing it you might as well upgrade in the process.

Talyn said:

The computers don't like low voltage. They do weird things as you saw with your transmission. if you are replacing it you might as well upgrade in the process.

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x2, also, you could have unplugged the TCU and had manual shifting to get you home.

what year and what kind of wheeling? i am not sure if RENIX can use the zj alt. and if you were mudding then that could be the culprit. alt and starters dont react too kindly to mud.

edit: did you check the trans fluid level? do you have a trans temp guage.

stewie said:

what year and what kind of wheeling? i am not sure if RENIX can use the zj alt. and if you were mudding then that could be the culprit. alt and starters dont react too kindly to mud.

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I am 99% sure renix can't use a ZJ alt, but there is an upgrade for the renix. I killed an alt going through mud.. and an engine.

If it comes and goes like that, it is more likely the connections than the alternator itself. Take all battery terminals and grounds apart, clean them and reassemble. To clean them use scotchbrite or sandpaper, and rinse debris with brake cleaner, spray start or electical contact cleaner. May as well do the alternator connections too.

Talyn said:

I am 99% sure renix can't use a ZJ alt, but there is an upgrade for the renix. I killed an alt going through mud.. and an engine.

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In my experience, after going through the mud and getting low voltage, the slip rings and brushes in the alternator are coated with mud. Sometimes the mud bakes on there (clay) sometimes it wears off. If left in there and mixed with sand it can grind down your brushes.
Regulators can fail, as can the diodes, rare but it happens. Some current can leak to ground through the wet wiring and connectors. Though line leakage usually doesn't cause more than temporary problems if any.
I mud often and when my alternator stops charging, most times a cleaning will bring it back to life. Very hot water and compressed air.
Upgrading to a higher amp alternator will likely not help any.
Soaking an alternator in coolant can kill it quick, it can short internally and cook off. Coolant conducts better than water alone or even a water mud mix.

RENIX can not use the ZJ alternator. RENIX uses the Delco CS-130 internally-regulated alternator, while HO uses the Nippondenso externally-regulated alternator.

The good thing is that the Delco CS-130 is painfully easy to upgrade, so no worries there. Parts abound, and any shop can crank the thing up for you with very little effort if you don't feel like tackling it yourself.

thanks for the replies guy. My rig's a 93 country. When I bought it the engine was blown so it was replaced with a 4.6 stroker. The jeeep had 200000 miles but I reused pretty much everything including the factory alt. I'll try cleaning and checking the wiring like winterbeater suggests. and see what happens.