2000 jeep cherokee sport alt not charging checked volts 12.5 everywhere even when running

Yes, it could be a fusable link. It could also be a blown ECU module (i.e "computer"). Test for 12 volts from the positive cable to the starter. Then check for 12 volts to the solenoid (with someone else turning the key). However, the fact that so many systems went out after the jump, it doesn't sound like a fuseble link to the starter. I'd check for a bad ignition fuse in the _cab_ section of the vehicle; (either under or on the side of the dashboard). It would be worth your time to check every fuse (everywhere) regardless of what it's says it's for. My "best guess" is a bad ignition fuse or possibly even a bad ignition switch. The only problem with the fuseable link theory is that you have affected systems beyond the starter. A bad ignition fuse or ignition switch makes more sense... and hopefully not a blown ECU module.

By the way... The proper way to jump is to start with both vehicles turned off. Then, do not put the negative leads on the batteries, but rather connect them to an engine "ground" location. Then, start the "good" vehicle first, let it run a minute or so, then with the running vehicle at a slightly higher idle (step a little bit on the gas pedal), then the "dead" vehicle tries to start. After starting, disconnect cables on the "good" vehicle first, and do so by removing the "ground" first.

Best of luck...

Check for power to the small wires to alt. needs power to those to charge. Could be a fusable link in harness.

nothing wrong with the ECM unless it has the voltage regulator as part of the system
indicates faulty wiring and faulty alternator
have a load test done on the battery
have an auto electrician do a full charging system check
charging voltage should be 14.5-14.8 volts DC
battery voltage should be 12-13.5 volts dropping to 11 volts when cranking the engine
make sure that the drive belt tension is correct and the belt is in good condition

95 GC (this car the ENGINE PCM/ECU controls charge at all times.)
this year, the alternator is not a Standalone ALT> no internal reg.
my CHARGE lamp is on, is it? ah, Check battery above is not a verb its a lamp glowing. gotcha.
The system is called that a charging system
you connect any any voltmeter to the car battery
it must read 13.3 to 15v. running or the charge system is in failure mode.
top reasons,
1: bad batteries, yes, the Alternator reg, might just give up on a bad battery and just not attempt to charge it. so try that first. and the'
battery is the #1 failure on all cars...
corroded battery terminals or cable or alternator not grounded do to corrosion.
2: Fuse 6 or 8 blown in the PDC, both 60amp huge fuses.
3: bad wiring. bad connections to any of the alternators 5 connections.
5: the ASD relay can kill the ALT field current. as can the PCM.
6: bad ALT.
7: bad PCM.at pin C141.

i recommend (DIY) the FSM tests. or alldata.com .

there are test on car for each type failure.
id start with battery.

stock car YJ ? , or all hacked up. (old cars get hacked)
2.5 or 4.0 liter engine? still have a real jeep alternator not upgraded?

loss of electrical power (first rule, we never need to guess.!!!)
not with a voltmeter. (tool that costs $20 )
alternator good (by what means, autozoned?) ( we can find out one car)
but low on gauge. what gauge in dash voltmeter.? sure...
i think you car has no charge lamp only the dash VM.

own an volt meter? a DMM? hand volt meter?

1: if the alternator charge lamp is stuck on driving.
2: is battery voltage at 13.3 to 15vdc with engine at 800 RPM idling
alternator belt not slipping, for sure.....???
if the battery voltage is near 12.5v and falling running that is
an Alternator system failure, note i said, system. !!!

this is first. if we get to here. we can find the real cause.
test 3:
is the charge lamp on keyon, and goes out running?
make sure the big fuse for the alternator in the engine bay fuse
box is not blown, 50amp?

I have no 95 FSM and my online source sucks for 95

Alternator dead: (alt good)
1: belt slipping . engine at 300rpm, nah.
2: fuse blown, the big one. (engine bay fuse box)
3: ;wrong alternator, there are many, most others will fail, even good ones.......
4: alternator ground bad. (end to end, to battery minus)
5: bad wiring to same. bad connections, any to battery or alt.
6: some jeeps the PCM has the field regulator, see link below.
ECU pin 20 , is field pin, it is on 95, 4.0L (engine not stated)

is the CEL lamp on, and throwing code 41 DTC?, alt, field errors?

the alt has 4 pins, battery, field,ground and voltage sense.
The reg is in the PCM. and if bad is a bad $3 transistor..
see same form for fix for that issue..

i think this is same as your. 1996 is big change year.
http://www.jeepforum.com/forum/f12/1993-wrangler-pcm-ecu-ecm-pin-out-diagram-1170004/


you can test the alt, PCM wire pulled !, by full fielding the alt.
grounding the field term, no wires on field pin of alt.
see FSM for details on that.
The PCM modulates the field pin to control charge at all times.

Hello. If your battery is not charging while driving, often it is due to low or bad voltage from your voltage regulator, which is also in the Alternator usually on these vehicles. Your engine has been running off the battery only and draining it, not using the alternator's power. Here are some things to look for and a question for clarification:

If you actually replaced the alternator already your regulator should be good. But to clarify your problem report, did you replace the alternator or only check it? It may take several checks while truck is running to catch the problem. If you have not done so already you will need to verify that voltage (13.9 volts or more) is actually reaching right to your battery. 12Volts will not be enough, that means something is wrong and is just battery volts. Please do this test while your Jeep is running, with lights on. DC volts across the battery need to be about 14 Volts while all is on. If you don't get that either the Alternator/VR is bad OR bad connection to it.

The alternator should be installed in the truck for voltage testing. Proper voltage with engine running is 13.5 to 14.5 volts at the battery terminals. If it reads 12.6 volts, the wire between the alternator output and the battery is open.

Check battery voltage should be 12v or better with motor off. start engine read voltage again should be 12.9 or better and then turn all accessories on...voltage should be same or slight y less but best would be at least 13v let it idle and volts should not creep downward..
Volts should never be below 12 and never at 14 except for a brief time after startup. Turn engine off and disable ignition system, then check across battery while craqnking. Volts should not go below 9.5. If so, have batt charged and load tested. If good, replace starter. No valid electrical computer testing can be done without a fully charged battery.

well , the ECU runs the alternator. (DG wire "dark green")
the alternator field is controlled 100% by PCM reg , inside PCM.
so..... if the running engine has 13.3, to 15vdc the alt is working
if lower, its not. (rpm on engine 800 or more)

not scanning the PCM a the CEL glow, you missed the boat.
why not scan it. see why the PCM is upset (DTC errors stored)

see the 2 lower pins below , those go to PCM.
in theory if the field in the old BAD ALT, was shorted.
that could in fact, burn up the PCM regulator.
shorting outputs of PCM , does that in most cases.
im the poor sod that fixes PCM's.so....

check the battery