ParadiseMJ Posted February 12, 2016 Share Posted February 12, 2016 OK, I've been reading about similar problems, didn't want to hijack so here I am. I had intermittent voltage gauge readings. Sometimes it reads straight up, sometime a little to the left and if I turn on the blower, or any other accessory it dips considerably. The lights are strong. Driving home yesterday, tooling along at 60-65...the MJ just quit. I coasted to the side, All the electrics in the truck were working...radio, gauges, interior lights, headlights. The thing just died. So I sat there for a couple minutes... Turned the key, started right up. Drove the rest of the way home. But the gauge was on 9, and as I drove the 6-7 remaining miles it built itself up to reading straight up, slowly. Backstory: I had been having problems with the starter. It would start, run fine...then wouldn't start, like nothing. No crank, no click, nada. I'd climb under, check the wires on the starter, tap the starter...started right up. Replaced the starter and that problem went away. The only thing out of place was the front axle vent line was dislodged and hanging (weird). Any ideas? Link to comment Share on other sites More sharing options...
87MJTIM Posted February 13, 2016 Share Posted February 13, 2016 CPS? Similar symptoms years ago (in a galaxy far away). Truck just died on the highway. I would crank but not fire. Still had electrics. Link to comment Share on other sites More sharing options...
ParadiseMJ Posted February 13, 2016 Author Share Posted February 13, 2016 The dealer CPS is about 2K miles old. The problem is that all the lights work, the gauge goes back & forth...even with the lights bright. When I turn the key. I get either nothing, or it cranks and starts. Then the gauge starts out low and eventually builds up after it starts and runs. Link to comment Share on other sites More sharing options...
cruiser54 Posted February 13, 2016 Share Posted February 13, 2016 I bet your alternator might be dying. Or the 2 wire connector is crudded up. How long since you did a connector refreshing under the hood? I can't remember what years your MJ is. Link to comment Share on other sites More sharing options...
ParadiseMJ Posted February 13, 2016 Author Share Posted February 13, 2016 It's an 88 4.0 (AW4) I have never eliminated the C101, but 've cleaned all the connectors, headlights (and a headlight harness upgrade) did the grounds in the harness, body, block, dipstick...a year or so ago. I'll bet you're right about the alternator OR more likely the wire connection. The gauge has never been quite right. When the gauge reads 10-11, the battery reads 13.5 - 14 or so. I also test it at the starter relay and an aux circuit breaker for lights etc. for power and it always reads ~12.5 when off and 13.5 - 14 while running. This weekend sucks for getting anything done. Wife has me nailed down with grandkids and Valentine's day so I'll be looking at it on Monday. Thanks for the help. Link to comment Share on other sites More sharing options...
cruiser54 Posted February 13, 2016 Share Posted February 13, 2016 Ever do Tip 18 or upgrade your cables? Link to comment Share on other sites More sharing options...
Gene Posted February 13, 2016 Share Posted February 13, 2016 Hi paradise, Look at it this way. If the voltage at the gauge is low, there are two possibilities. First, the voltage in the whole system may be low. This would most likely be a bad alternator, much less likely a bad battery. Second, which is more likely, the voltage at the battery and alternator is fine, but it's getting "lost" somewhere in the wiring. Do you have a volt meter? If not, get a cheap one. This should be less than $10 at Harbor freight. It may be called a multi meter. Set the voltmeter on about 20 V DC, and check the voltage at the battery, with the engine off. Typically, a good battery, fully charge, will be around 12.7 V or higher. Then start the engine, and with the engine idling, check the voltage at the battery again. Typically this will be at least 1 V higher, about 13.8 or so. Now, with the engine still idling, turn the headlights and wipers on. The voltage will not be as high, but it still should be over 13 V. To be absolutely certain, carry the voltmeter with you, and when things are "acting up", check the voltage of the battery then. If the voltage of the battery is 13, and voltage at the gauge is 7, then the alternator and battery are good, you're losing voltage somewhere in the wiring. Cruisers tips address this in detail, although apparently there are also problems with the connectors to the ignition switch as well. Finally, the two things you are experiencing may not be related. It's possible that there is a separate problem causing the stalling, not related to the voltage loss. Good luck! Gene Link to comment Share on other sites More sharing options...
Gene Posted February 13, 2016 Share Posted February 13, 2016 Hi paradise, I actually missed your latest post above, where you posted the voltage readings. Sorry. Based on those, it's overwhelmingly likely the problem is not battery or alternator, but somewhere in the wiring. It still wouldn't hurt to check battery voltage right at the time it's acting up. Gene Link to comment Share on other sites More sharing options...
HOrnbrod Posted February 13, 2016 Share Posted February 13, 2016 Good info from Jon Kelly: 1) RENIX used a Delco CS-130 alternator, which is internally regulated.2) RENIX alternators are grounded through the mount, the engine block, and the main ground lead about 2/3 back (it's attached above and behind the distributor, passenger side.) Valve cover seepage often gets into this connection.3) The RENIX IP voltmeter is a notorious liar. As mentioned, verify that suspect reading with an independent DMM, connect it to the battery.Delco alternators are actually pretty robust, I've used them on Gawd knows how many conversions (SI and CS series) and in myriad industrial setups. I prefer them over just about anything else.However, Point #2 should be particularly noted. If you think you're having ground trouble (a typical cause for "floating voltage at steady-state operation,) I would suggest making a test lead out of 10AWG or maybe 8AWG wire - make it long enough to go from the alternator case to the battery - post. You may use clips on both ends, or you can put a 5/16" or 3/8" ring on one end - there is a boss on the back of the alternator case, drilled & tapped M8-1.25 (use a 20m/m long screw. Using an overlong screw there can bind the rotor - it's a through hole, usually.)If this additional ground settles down your voltage readings, then clean your main ground (since it's also the primary ground for engine management sensors,) and consider making the alternator ground a permanent installation (rings on both ends - a 5/16" or 3/8" will also fit to the battery clamp bolt and most binding posts.) The alternator direct ground may also be run to the stud where the primary ground attaches - but why not just go directly to the battery? Use min. 10AWG wire for a permanent ground (although 6AWG - same as OEM mains - would be preferred. However, you're augmenting an existing ground, not creating one from whole cloth.)Floating output on RENIX is actually a fairly common issue - and often not the alternator's or regulator's fault...As far as a parts house test? Don't bother taking your alternator in - those benches aren't worth a damn (I used to work on them. They check voltage at 1-2A - but it's current that is the critical factor!) The little red roll-around Bear ARBST (common in parts houses) that tests alternators on-vehicle is a bit more effective, since it will actually load the system, but even that is of limited utility. I would suggest finding a local starter/alternator/generator shop and going there - you'll get a better part, and they can actually wring the damned thing out for you and find out what's really doing on (your issue may also be something like "diode ripple," from failing rectifier diodes. The parts house bench can't test for that.)Sure, the small local shop might not offer a "lifetime warranty." But, the best warranty is the one you don't need - and I've never needed a warranty replacement from my local shop. (I recently talked Rod into doing mail-order as well, click here - www.kelleyswip.com/sjg.html. You'd deal with Rod directly, and do note that he keeps banker's hours on the West Coast. But, his work is ROCK SOLID and that more than makes up for the inconvenience...) Link to comment Share on other sites More sharing options...
ParadiseMJ Posted February 13, 2016 Author Share Posted February 13, 2016 Thanks guys, All things I'll have to check and confirm/eliminate. I agree on the gauge itself being off but if I wasn't getting the weird symptoms I'd go right to that. I will get to work on it early this week. Link to comment Share on other sites More sharing options...
Gene Posted February 13, 2016 Share Posted February 13, 2016 Delco alternators are actually pretty robust, I've used them on Gawd knows how many conversions (SI and CS series) and in myriad industrial setups. I prefer them over just about anything else. Hi hornbrod, Great information (as usual) in this post! I'm surprised at the comment about the reliability of these alternators. A local alternator shop said that they have experienced a very high failure rate with these. Apparently when you have a relatively high output alternator, in a fairly small non-ventilated case, heat builds up, and the heat will kill the diodes. This is especially a problem when the alternator has a prolonged very high output. For example, if you have a dead battery, jump the vehicle to started, and then run to charge up the battery, the extra load will cause extra heat and may kill the alternator. About 15 years ago, when my alternator went bad for the third time, I found an "Iceberg alternator" kit. At that time I bought it from JC Whitney. This had additional cooling on the diodes, I think what was basically flat on the original design had cooling fins that projected externally on the conversion. This alternator has held up for many years. Not much mileage, but lots of time! Again, thanks for the post. Gene Link to comment Share on other sites More sharing options...
Gene Posted February 13, 2016 Share Posted February 13, 2016 https://alternatorparts.com/7130-7140.html looks like "Iceberg" kits still available. Gene Link to comment Share on other sites More sharing options...
cruiser54 Posted February 13, 2016 Share Posted February 13, 2016 Good info from Jon Kelly: 1) RENIX used a Delco CS-130 alternator, which is internally regulated. 2) RENIX alternators are grounded through the mount, the engine block, and the main ground lead about 2/3 back (it's attached above and behind the distributor, passenger side.) Valve cover seepage often gets into this connection. 3) The RENIX IP voltmeter is a notorious liar. As mentioned, verify that suspect reading with an independent DMM, connect it to the battery. Delco alternators are actually pretty robust, I've used them on Gawd knows how many conversions (SI and CS series) and in myriad industrial setups. I prefer them over just about anything else. However, Point #2 should be particularly noted. If you think you're having ground trouble (a typical cause for "floating voltage at steady-state operation,) I would suggest making a test lead out of 10AWG or maybe 8AWG wire - make it long enough to go from the alternator case to the battery - post. You may use clips on both ends, or you can put a 5/16" or 3/8" ring on one end - there is a boss on the back of the alternator case, drilled & tapped M8-1.25 (use a 20m/m long screw. Using an overlong screw there can bind the rotor - it's a through hole, usually.) If this additional ground settles down your voltage readings, then clean your main ground (since it's also the primary ground for engine management sensors,) and consider making the alternator ground a permanent installation (rings on both ends - a 5/16" or 3/8" will also fit to the battery clamp bolt and most binding posts.) The alternator direct ground may also be run to the stud where the primary ground attaches - but why not just go directly to the battery? Use min. 10AWG wire for a permanent ground (although 6AWG - same as OEM mains - would be preferred. However, you're augmenting an existing ground, not creating one from whole cloth.) Floating output on RENIX is actually a fairly common issue - and often not the alternator's or regulator's fault... As far as a parts house test? Don't bother taking your alternator in - those benches aren't worth a damn (I used to work on them. They check voltage at 1-2A - but it's current that is the critical factor!) The little red roll-around Bear ARBST (common in parts houses) that tests alternators on-vehicle is a bit more effective, since it will actually load the system, but even that is of limited utility. I would suggest finding a local starter/alternator/generator shop and going there - you'll get a better part, and they can actually wring the damned thing out for you and find out what's really doing on (your issue may also be something like "diode ripple," from failing rectifier diodes. The parts house bench can't test for that.) Sure, the small local shop might not offer a "lifetime warranty." But, the best warranty is the one you don't need - and I've never needed a warranty replacement from my local shop. (I recently talked Rod into doing mail-order as well, click here - www.kelleyswip.com/sjg.html. You'd deal with Rod directly, and do note that he keeps banker's hours on the West Coast. But, his work is ROCK SOLID and that more than makes up for the inconvenience...) Makes me wonder if in my Ground Refreshing Tip there should be a note to run the extra ground cable from an alternator bolt to the passenger side inner fender......... Link to comment Share on other sites More sharing options...
HOrnbrod Posted February 13, 2016 Share Posted February 13, 2016 Si - it sure wouldn't hurt. I ran an extra case ground wire when I swapped in a 136A Nippon Denso alternator. The VM doesn't drop as much as before when running all the lights and motors. Link to comment Share on other sites More sharing options...
cruiser54 Posted February 13, 2016 Share Posted February 13, 2016 Thanks for the homework assignment......................... Link to comment Share on other sites More sharing options...
HOrnbrod Posted February 13, 2016 Share Posted February 13, 2016 :thumbsup: Link to comment Share on other sites More sharing options...
cruiser54 Posted February 13, 2016 Share Posted February 13, 2016 Just what I need....... Link to comment Share on other sites More sharing options...
HOrnbrod Posted February 13, 2016 Share Posted February 13, 2016 Do the below alt voltage drop test to verify. My positive side was fine, but the negative side was dropping a bit over .5V. After adding the extra case ground wire the drop was negligible and made for a more stable dash VM. Image Not Found Link to comment Share on other sites More sharing options...
rocketwheels Posted February 13, 2016 Share Posted February 13, 2016 Thanks for this info , as well ! Link to comment Share on other sites More sharing options...
ParadiseMJ Posted February 16, 2016 Author Share Posted February 16, 2016 OK, so I dove in to my electrics this afternoon. My aux lights ground, from the relay has a common ground for two of the relays. It was loose. I refreshed that and used a tighter fitting sheet metal screw. Now there is zero drop in voltage when I flick them on. Hurrah. I found that the PO had screwed the switch ground screw through plastic into metal, so it wasn't really a good ground anyway. There is still a significant drop in voltage when I turn on my blower motor (at the gauge, but not at the battery). I have to move some stuff around to see if adding an extra ground to the blower if anyone thinks that would work. I read something by Cruiser about that. I also checked my already consolidated sensor grounds that are all soldered now, good and tight. I have yet to run an extra ground to the alternator body. I checked my output and two wire connector at the alternator. The two wire looks brand new inside (I did clean this out and grease it when I installed the alternator 3 yrs. ago). The output is showing 14.7 VDC when running. I checked all the fusible links at the starter relay, all tight and hard. The starter relay is old and rusty, but still seems to work fine - volt wise. I checked just about every connector inside the engine bay, sprayed 'em out, and put a thin layer of DG on all. When I reconnected them I also wrapped a length of electrical tape around them like I usually do, to keep them secure and dry. My volt gauge is still a little wonky. At least I've eliminated some stuff. Like I said, the only time the volt gauge really shows a significant drop is when I turn on the blower OR the radio, which are my next two suspects. If I punch the cig lighter...no drop. Driving lights used to show a drop...now they don't, so there's some progress. It still cranks and starts like a teenager, BUT sometimes I turn the key and it's just dead...and I've had two incidents where it just crapped out with no warning, deead in the water. I'm going out in a bit to adjust my NSS because last week I noticed that the reverse lights were on when the Jeep was parked...in PARK. That's one of the things that told me I needed to do some fine tuning on the wiring. Sorry about the long post, but I'm just thinking out loud. So, here's a QUESTION. If the NSS is loose, out of adjustment or generally screwed up...could it make the Jeep die, after it was started and running...I mean could it kill the engine?? Thanks for the help. If anyone has any more input, it's welcomed. Link to comment Share on other sites More sharing options...
gogmorgo Posted February 16, 2016 Share Posted February 16, 2016 Don't think the NSS could kill the motor. When it's perfectly operable, it runs in all gears. Maybe if it controlled torque converter it could lock and stall at a weird time, but I don't think it has anything to do with the tc. Link to comment Share on other sites More sharing options...
ParadiseMJ Posted February 16, 2016 Author Share Posted February 16, 2016 So the only issues left are: 1. Engine cuts out, usually at speed, only a couple times so far. Just cruisin' along and the next second, engine dead, all electrics work otherwise. Then it starts right back up. 2. Not a fuel problem...as far as I can tell...no stutter, sputter or "run out of gas" feeling. Pressure good, pump primes everytime. Although the pump is old... :???: 3. It'll run fine all day. then I'll get in to start it (hot or cold) and I get nothin'. Kinda why I'm looking at the NSS, besides the inoperable reverse lights, and it won't start in Neutral...ALL fuses good. 4. Voltage drop when I turn on blower, not lights, not cig lighter, not radio...just the blower. Working on that. Link to comment Share on other sites More sharing options...
cruiser54 Posted February 16, 2016 Share Posted February 16, 2016 4: see www.cruiser54.com. Blower motor ground. Link to comment Share on other sites More sharing options...
Gene Posted February 16, 2016 Share Posted February 16, 2016 Hi paradise, Probably 3 separate issues. 1+2 will be very hard to track down. You may not solve that til it gets worse. 3 sounds like neutral safety switch, especially with it not starting in neutral. 4 may be close to "the nature of the beast see this thread http://comancheclub.com/topic/49226-heater-sapping-power/ Good luck! Gene Link to comment Share on other sites More sharing options...
cruiser54 Posted February 16, 2016 Share Posted February 16, 2016 Here buddy: http://cruiser54.com/?p=211 Link to comment Share on other sites More sharing options...
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