Strokermjcomanche Posted July 6, 2014 Share Posted July 6, 2014 I'm having issues with my dd 89 mj that I recently upgraded to a 95 xj driveline ( 4.0 aw4 np242 ). Even before I did the swap it read low 13's in voltage with no headlights or a/c on . If I put the a/c on, or the headlights , or the electric cooling fan comes on it dives into the high 11's or low 12's . I also confirmed the guage was correct with a charging system tester at orielys .When I did the swap I refreshed / added new grounds where needed . It's a new alternator and I know the voltage is controlled by the computer in that year . Any other things I should do to try to fix this issue? I want to wire up some lights but want to address this issue first . As always any and all help is much appreciated . Thanks Link to comment Share on other sites More sharing options...
Jeep Driver Posted July 6, 2014 Share Posted July 6, 2014 Did you replace the battery cables? Cable from alt to breaker? Link to comment Share on other sites More sharing options...
Strokermjcomanche Posted July 6, 2014 Author Share Posted July 6, 2014 No but they are all clean and the drivetrain only has 96 k on it . Link to comment Share on other sites More sharing options...
TheDude Posted July 6, 2014 Share Posted July 6, 2014 You should be able to check the wires condition by using a Multimeter to see if the volts drop from one side of the cable to the other. Link to comment Share on other sites More sharing options...
HOrnbrod Posted July 6, 2014 Share Posted July 6, 2014 Your alternator should put out 13.5V - 14.5V across the battery terminals, depending on the battery charge condition and applied load. As long as there is no major dimming of the headlamps at idle or slow starting engine turnover, I wouldn't be worried about the voltmeter bouncing between 11V and 13V. My 91 has done that since I've had it in spite of new mains cables, beefed up grounds including the instrument cluster, and a 134A alternator. I think it's because of the voltmeter's sensing point, a know problem on OBD1 systems. Link to comment Share on other sites More sharing options...
Strokermjcomanche Posted July 6, 2014 Author Share Posted July 6, 2014 Cool thanks , I just don't want to have any problems in the winter time when I'm at my friends cabin with 2feet of snow in the middle of the night . Hornbrod what alternator are you using ? Link to comment Share on other sites More sharing options...
HOrnbrod Posted July 6, 2014 Share Posted July 6, 2014 This one. Link to comment Share on other sites More sharing options...
Strokermjcomanche Posted July 6, 2014 Author Share Posted July 6, 2014 Looks to be a direct bolt on? I get everything at cost at the parts store I worked at so this might be my next project. thanks Link to comment Share on other sites More sharing options...
HOrnbrod Posted July 6, 2014 Share Posted July 6, 2014 For the 4.0 HOs it is basically PnP. Even though some claim they had to do a little grinding on the alt brackets I didn't have to. It was tight going in and took a little while, but it fit. Also you have to reclock the plastic cable guide on the back - easy, and the existing pulley has seven ribs. You can either replace the pulley with a six rib version, or use the existing seven rib pulley and align the belt toward the rear like I did. I have been running this alternator for years with no problems. Don't know how it would fit in the 2.5 engine though. :dunno: Link to comment Share on other sites More sharing options...
desertmike Posted July 7, 2014 Share Posted July 7, 2014 Quick question. I have an 89 XJ and 88 MJ both 4.0. I need some more power for winches. Will these fit with a little work and are they electrically compatable? Thanks Link to comment Share on other sites More sharing options...
88Chief4x4 Posted July 7, 2014 Share Posted July 7, 2014 I was reading low volts on mine too, I put in new battery terminals from advanced and now my voltage is back to normal Link to comment Share on other sites More sharing options...
HOrnbrod Posted July 7, 2014 Share Posted July 7, 2014 Quick question. I have an 89 XJ and 88 MJ both 4.0. I need some more power for winches. Will these fit with a little work and are they electrically compatable? Thanks It's been done on Renix stuff, but it's more difficult. You would need the alternator bracketry from an HO and an external regulator. On the HOs the Denso alts are regulated by the ECU. Link to comment Share on other sites More sharing options...
desertmike Posted July 7, 2014 Share Posted July 7, 2014 Thanks hornbrod Did some more checking including your some of your posts and I think I'm going to see about getting mine rewound. Link to comment Share on other sites More sharing options...
HOrnbrod Posted July 7, 2014 Share Posted July 7, 2014 Thanks hornbrod Did some more checking including your some of your posts and I think I'm going to see about getting mine rewound. Yep, I think that's your best option to get more juice out of your Delco. Back in the day that was the first option: bring your tired generator, alt or starter to a reliable local shop and have them rebuilt and rewound. Today it's cheaper to pick up an offshore "remanufactured" POS from one of the chain auto parts store that dies usually in the first year. As a result the good local shops have mostly gone under. Link to comment Share on other sites More sharing options...
desertmike Posted July 7, 2014 Share Posted July 7, 2014 hornbrod Checked with a local rebuilder and he can upgrade mine to about 140A for about $125 or so. Link to comment Share on other sites More sharing options...
HOrnbrod Posted July 7, 2014 Share Posted July 7, 2014 That sounds like a plan. While you're at it, you should also upgrade the mains cables. You can't beat these from Jon Kelly: http://www.geocities.com/JeepI6Power/electric.html Link to comment Share on other sites More sharing options...
Strokermjcomanche Posted September 10, 2014 Author Share Posted September 10, 2014 Just did my alternator upgrade today to a 136a Oem part#56027913. Turning the headlights , blower motor or if the cooling fan comes on the voltage still drops considerably around high10s - low11s . If I install the lights I have I'm going to bet that's going to drop the volts even lower and I'm not looking to kill my battery . Can I install a different regulator? Or any other ideas? Thanks I've changed the entire engine harness and PCM , new battery and now a mopar nos alternator since this problem with no improvement . I'm lost and frustrated any help is appreciated . Link to comment Share on other sites More sharing options...
Jeep Driver Posted September 10, 2014 Share Posted September 10, 2014 Just did my alternator upgrade today to a 136a Oem part#56027913. Turning the headlights , blower motor or if the cooling fan comes on the voltage still drops considerably around high10s - low11s . If I install the lights I have I'm going to bet that's going to drop the volts even lower and I'm not looking to kill my battery . Can I install a different regulator? Or any other ideas? Thanks I've changed the entire engine harness and PCM , new battery and now a mopar nos alternator since this problem with no improvement . I'm lost and frustrated any help is appreciated . A bad battery with a dead cell is like a black hole and will suck the life out of everything you got. Link to comment Share on other sites More sharing options...
Strokermjcomanche Posted September 10, 2014 Author Share Posted September 10, 2014 It's a brand new optima, but I have a new mopar battery in my other truck I can swap for diagnosing that . Link to comment Share on other sites More sharing options...
Comanchemodder Posted September 10, 2014 Share Posted September 10, 2014 It's a new alternator and I know the voltage is controlled by the computer in that year . So did you install an external regulator or do you have the computer from that year with your drivetrain swap? When I swapped a later 2.5 into my RENIX, I used the later alternator and therefore needed an external regulator. Without the regulator, the alternator never charged. Link to comment Share on other sites More sharing options...
Strokermjcomanche Posted September 10, 2014 Author Share Posted September 10, 2014 Yes its the complete 95 xj 4.0 driveline, harness etc . The alt charges but IMO it's not putting out enough volts under load . I'm going to grab a multimeter to confirm today . Link to comment Share on other sites More sharing options...
HOrnbrod Posted September 10, 2014 Share Posted September 10, 2014 Measure battery voltage4, not running. It should read about 12.5V. Then put a meter across the battery and measure the charge voltage at just above idle. Should be 13.8 - 14.5 volts or so depending on battery condition. Then turn on lights, fans, blowers, etc. while monitoring the battery voltage. It should remain the same even if your dash voltmeter drops. As long as it charging the battery at full load, no worries. My truck does the same thing on the dash voltmeter ever since I swapped the alternator and installed new mains cables years ago. I suspect it's a wonky dash meter or maybe a dirty connection somewhere between the meter sensing point at the PDC and the meter. It's a pretty common problem. Also do Cruiser's extended cluster ground wire tip for the cluster - that helped me a bit. Link to comment Share on other sites More sharing options...
Strokermjcomanche Posted September 16, 2014 Author Share Posted September 16, 2014 All is good now or was good from the getgo . I bought a new fluke multimeter and I have 14.5 v with everything on ( blower , lights , cooling fan , fog lights ... )I guess the orileys tester is not as accurate as I thought . Thanks for all the help . Now I just need to get the trans to shift like normal !! Link to comment Share on other sites More sharing options...
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