Question about 1998 Jeep Wrangler
Pin #20 (dark green wire) on the computer should run to the alternator field circuit. (be aware...Jeep changes color codes more than I change my socks)
The regulator is part of the computer and is not separately available. When the computer sees low voltage it provides a ground to the dark green wire that causes the alternator to begin charging.
To determine if the alternator/regulator combination is working, put a volt meter across the battery terminals (you need a fully charged and load tested battery to do this) With the engine running and no accessories on, the charge rate should be about 13.5 to 13.9 Not above 14. With all accessories on and headlights on high beam, the charge rate should not drop below 13 (at worst 12.5) and should not ever drop below that regardless of how long it runs.
If it does, and the alternator was already proven as good, then the regulator (in your case, the computer) needs to be replaced.
But, before doing that, check the fuses in the power distribution center to make sure the one for the alternator is not blown. Also make sure that the larger alternator wire has full battery voltage (check at the alternator connection) If there is lower or no voltage there, find out why.
Another thing to check is that all ground connections are good at the battery, engine, firewall and especially at the left fender where the computer is connected. (if the ground wires at the computer are not properly grounded it can't send a ground to the alternator
There is a "work around" where you can wire in an old style regulator but I don't remember exactly what goes where but it will turn the check engine light on and therefore may cause you to fail a vehicle inspection though the charging system has nothing to do with emissions..Therefore, I don't recommend it unless you only use the jeep off road.
Hope this helps a bit.
Posted on Jan 31, 2010
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Posted on Jan 02, 2017
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