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Alternator question
- Thread starter Drew00
- Start date
- Location
- In the islands
I am not sure of the color on your XJ but on the 1996 the dark green and orange wire is the positive from the ASD (Automatic Shut Down) relay. It have power for the first few seconds when the key is turned on and again while cranking the engine. It is also on continuously when the engine is running. The green wire come directly from the PCM. It is the ground which is toggled on and off.....think regulator.... to keep the charging voltage within specs.
- Location
- In the islands
I guess you could do that if that is what you want to but.....I see no need to do that if the relay work, if the fuel pump run, if the injectors fire, if the 02 sensor reads properly, if the spark plugs all fire,....I could go on and on but that is just me.
If I were to use a wire direct I would first remove that/those wire/s and secure them properly to avoid shorting the ignition system. Why? If that were to happen the XJ could become in - operable with possibly damaged wiring and or PCM. Just saying.
- Location
- In the islands
To check the alternator directly, remove the two small wires and replace them with two wires temporarily. Connect one wire to a positive source, the battery positive will be fine. Attach a volt meter to the battery. Start the engine and run it up to about 2,000 RPM. Touch the other wire from the alternator to a clean grounded metal on the engine. If the alternator is good the voltage would increase to 18 +/- . Be careful doing this. High voltage for an extended period could damage other electronics on the XJ.
These instructions come directly from a 1996 cd workshop manual.
- Location
- In the islands
Having it checked is a very good idea.
I conducted the above test on my XJ a year ago in response to a low voltage problem over the years that progressively got worse. In my case the voltage at the battery seldom get up to 13 volts which it only did when the ambient temperature was 50 or below which is a seldom occurrence in Florida. Conducting that test, alternator easily got up to 18+ volts. The battery temperature sensor was the culprit.
I did the test without disconnecting the wires from the alternator. I attached a test lead to the dark green wire and ground it just long enough to verify 18 volts as indicated in the manual.
- Location
- In the islands
It would appear there is an electrical problem some where. Start by testing at the battery posts with the engine running. Voltage should be 13+ then work your way up to the guages. Pay special attention to the grounds.
From your forum name I assume your XJ is a 2000 year model. Someone here with the same year model would come in and help you out on the specifics for that year ground location.
Where did you get the alternator tested? It's been said that some regular auto parts store do not do a good job testing alternators. You did not say whether or not the battery go dead. That is why I suggest testing at the battery posts.
Going back to post #1, putting an independent positive wire on the alternator will not help unless that wire there right now is bad. Grounding the terminal with the plain green wire will definitely let you know whether or not the alternator is good; that is assuming that ignition /positive exist on the terminal with the green and orange wire when the engine is running. A simple volt meter is needed to trouble shoot this issue.
Testing at the battery with volt meter engine off is 11.5 - 12 volts. Doesn't change at all when engine is running. I'll try more testing grounds. I assume the battery will go dead. I haven't let it run very long. Trying to get it going by this weekend. Thanks again for the advice.
Jeep Driver
NAXJA Forum User
- Location
- Parrottsville
Jump post #2 to the battery +
This is the 'exciter' wire.
Now see if the alt will charge........should be at 14.2 volts when charging.
This is the 'exciter' wire.
Now see if the alt will charge........should be at 14.2 volts when charging.
Jeep Driver
NAXJA Forum User
- Location
- Parrottsville
trippled
NAXJA Forum User
- Location
- colorado springs, co
That diagram is not right. Full fielded alternators on Chrysler stuff can put out upwards of 17 volts. If it's ground controlled and the pcm has lost the driver internally, you can put in an older dodge external voltage regulator, but it's probably easier to get a junkyard pcm. I don't have a diagram handy, but if you jump the ground controlled field wire to ground momentarily, you should see the battery voltage jump if the pcm is not co trolling and everything else is working.
Jeep Driver
NAXJA Forum User
- Location
- Parrottsville
What year is the XJ?
Older Jeep used GM alts.
Older Jeep used GM alts.
- Location
- Minneapolis, MN
Have you inspected the alternator brushes ? Worn brushes will test "good", but not charge properly when on the road.
- Location
- In the islands
Yes, you are correct. That drawing is for an AC Delco. That year 2000 XJ uses a Nippondenso alternator. Post #6 explained how to load test the alternator in the vehicle. If the two small wires are removed from the alternator it would not matter which test lead go to which terminal. I think Drew00 would be able to do that test himself.
Removing both wires will completely isolate the alternator from both the ignition and the pcm ground also called the field driver.