Ad Radar

Automotive Forums  Where Car Enthusiasts Go to Discuss Cars Online

  
 
 
Home | Active Posts | Search | Log In / Register | Terms | FAQs
Xml
Item Posts   

1995 JEEP CHEROKEE CHARGING SYSTEM PROBLEMS (HELP!)

 
 | 
hampty_38 hampty_38
New User | Posts: 4 | Joined: 06/11
Posted: 06/24/11
02:24 PM

i have a 1995 jeep cherokee. a few months ago i had to replace the ecm because the injector drivers fried. it ran great for a few months and then i started getting the check engine light . but only after the vehicle had been running for about 10 min.  so i pulled the codes. codes #41 and #42  alternator field not switching properly and auto shutdown relay or control circut. i had the alternator tested and it came out ok. i looked for shorts. didnt find any. well after a week of driving, i started it and the check engine light is on. In addition to the other codes i have a new code #46. battery over charge. checked the batt with volt meter with vehicle off. 12.62 volts. started it and i got 17.85 volts and liquid bubbling out of the battery. quickly turned it off and im fearing that it is the ecm again . does anyone have any thoughts that may help me fix this problem. any and all help is appreciated. thanks.  

waynep7122 waynep7122
Addict | Posts: 4561 | Joined: 08/09
Posted: 06/24/11
05:51 PM

i would like you to do a few tests first... these take less than 5 minutes ...

start the engine.. turn on the headlights...

set your digital volt meter to 20 volts DC scale..

1... test from the positive battery post to the negative battery post...  14.1 to 14.7 volts is expected..

2... test from the negative battery post to the engine block... 0.04 volts is expected...

3... test from the negative battery post to the body....0.02 volts is expected..

4...  test from the engine block to the firewall... 0.02 volts is expected..

please post your results for the tests..

1.__________________________

2_________________________

3_________________________

4________________________

this is a STARTING POINT FOR TESTING..

if you get more or less than what i have posted...  you have a problem on that circuit...

i can do this test faster than i can get the digital volt meter out of my tool box...  

waynep7122 waynep7122
Addict | Posts: 4561 | Joined: 08/09
Posted: 06/24/11
07:21 PM

why am i having you check the grounds....  it's the first thing to check......


0900C152800a9e0a



0900C152800a9e06  

hampty_38 hampty_38
New User | Posts: 4 | Joined: 06/11
Posted: 06/24/11
07:44 PM

1._17.85_

2_.02_

3_.02_

4_.02  

waynep7122 waynep7122
Addict | Posts: 4561 | Joined: 08/09
Posted: 06/25/11
05:10 AM

there are several wires on the back of the alternator...

the dark green wire connects to the computer to pull the spinning rotor coil to ground ... there is always a place that it can be disconnected..      see it the alternator stops charging.......  it should.


the location to determinate the connector is usually where the complete harness for that area hooks to the main harness...


i have found several alternators that  charged with the dark green wire disconnected... and they would max charge also...

if your alternator still charges with the dark green wire unterminated... there is a internal short inside ... either the brush leads... or more likely inside the rotor.. where the wires from the rotor winding pass along in a groove in the shaft where the bearing is pressed on...

warning.. the alternators will usually pass a charging test with this problem..  as the tester usually just looks for output voltage...  not how much its making...  

waynep7122 waynep7122
Addict | Posts: 4561 | Joined: 08/09
Posted: 06/25/11
05:49 AM

if the alternator stops charging when you disconnect the dark green wire....  

check the rest of the wire for cuts or shorts back to pin 20 where the dark green wire connects to the ECM..

i have a 94 jeep repair section for the charging  

there might be a place to disconnect it at the large wiring connector near the alternator..

the factory service manual does not really cover the disconnect like i have used on other mopar charging systems..  

hampty_38 hampty_38
New User | Posts: 4 | Joined: 06/11
Posted: 06/25/11
11:52 AM

i pulled the alternator and had it tested again. it was producing 14.65 volts. with a max output of 15.20. while i have it off im checking all of the wires again. my manual does show that the drk green wire goes to the ecm. now it doesnt specify its purpous but i have an idea. the little black box that the green wire goes to that connects to the alternator has four connection points and one of those is for the drk green wire. from that point to the ecm i have continuity. but from that point to where the battery ground wire attaches to the body i also have continuity. is that supposed to be that way or is the little black box thing fried?  

waynep7122 waynep7122
Addict | Posts: 4561 | Joined: 08/09
Posted: 06/25/11
12:07 PM

do you have a scan tool...  if not flip the key on 3 times within 10 seconds... last position on..   the check engine light should flash.. codes...

do you get any codes in the 41 through 47???

look at section 8a  8b 8c....


the dark green wire is for the ECM to control how much the alternator charges..   when the ECM connects the dark green wire to ground.. and its usually a pulsing ground connection to limit the current into the rotor..  more ON time.. more output from the alternator..

finding a spot where you can disconnect the dark green wire from a harness connector.. will allow you to see if the alternator it's self is a problem.. or the ECM..

it really needs to be looked at with a scan tool... so you can see if the voltage the ECM is monitoring is actually the proper voltage...   if the ECM sees reduced voltage do to a bad connection to the ECM . it make try to make the alternator charge more to keep the charging system at proper output..


log in.. check messages to the left of where you log out at...  

hampty_38 hampty_38
New User | Posts: 4 | Joined: 06/11
Posted: 06/25/11
12:26 PM

i do not have a scan tool. i did pull the codes with the ignition. codes 41 42 46. and i did just have the alternator tested and it passed twice with output of 14. and a max output 0f 15. and with the alternator disconected the wire is showing constant ground to the body .  

Xml
Showbuyersguide Hide2
2015 Jeep Cherokee
Button Getmyprice
Body Style:
SUV
Rating:
N

Research Categories:

Sponsored Links

 
 
  • Trade-in-Value.com