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Old 03-11-2012, 08:03 PM   #1
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94 YJ battery will not charge

I'm not a mechanic by no means at all. This is the first I've even tried to work on a car. I have replaced the alternator, cleaned the battery ground, replaced the battery terminals...the battery won't charge. I can jump it off and drive it around but after turning it off, the battery is totally dead and that's after only 10 minutes of driving. Alternator bench tested good but had it tested inside Jeep and tested at 10.4 so that's why I replaced the alternator. The battery also bench tested good. This is a 1994 YJ with a Chevy 350 conversion.

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Old 03-11-2012, 08:10 PM   #2
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Make sure your alternator is hooked up correctly. I but a mud truck a while back and it had the same problem. The previous owner had hooked the alternator up wrong.

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Old 03-11-2012, 08:20 PM   #3
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I believe it's hooked up right. It was running fine and then died and wouldn't crank. The relay is not working on crank. Temporarily we wired up a switch inside Jeep so it's always on (hot wire), so we have to use the switch to turn it off. With that switch it cranks but now the battery won't hold a charge.
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Old 03-11-2012, 08:52 PM   #4
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Easy test to see if the alternator is charging properly.

With the engine running, remove the POSITIVE terminal from the battery. Engine should continue to run. If it dies, your alternator is not charging and is faulty or wired wrong.
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Old 03-11-2012, 09:03 PM   #5
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Well I currently have my distributor wired from my battery b/c I was having the cranking issues so if I disconnect the positive, I shut down my distributor. I have seen something about a PCM and ECM...any advice what are they/where are they? As I said, I am not a mechanic so every bit of help is appreciate. I'm a frustrated mom trying to help my teen son for 6 weeks now.
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Old 03-11-2012, 09:05 PM   #6
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More Info: This is how it all started...
I have a 1994 Jeep YJ that suddenly won't crank. A few years ago it was converted from a 4 cyl to a Chevy 350 (is not fuel injected). There is power from battery to relay but something is not giving signal from relay to distributor. Of the 5 prongs on the fuel pump relay, if I wire it to the middle prong it cranks but won't turn off. If I have it wired to the prong it has always been, it will turn over but won't crank. I've replaced the distributor cap and ignition coil even though the coil tested good. When I have it wired to the fuel pump relay as it should be, I go from 12v to 8v...is that normal? My teenage son was backing it into the driveway and it died and would no longer crank. The rotor does turn. Any ideas will be appreciated!
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Old 03-11-2012, 09:16 PM   #7
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So now I'm just having the battery charging issue b/c we hot wired the distributor and using a switch inside jeep to shut it off and for cranking.
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Old 03-11-2012, 09:40 PM   #8
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I've read in other posts about a PCM. Where is this located and remember this is has a 350 Chevy. I'm a frustrated mom trying to help my teen son fix his very cool Jeep.
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Old 03-12-2012, 08:37 AM   #9
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'94 YJ
Please help me restore their smiles
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Old 03-12-2012, 10:56 AM   #10
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If it's not Fuel injected your not using the PCM are you?
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Old 03-12-2012, 11:29 AM   #11
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Hi. I don't really know. I've been told it would probably be ECM instead of PCM. I'm not sure where to look to see if I am running on an ECM/PCM. Still trying to find that out. Perhaps you could tell me where to look.
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Old 03-12-2012, 12:24 PM   #12
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ECM/PCM are interchangeable terms. They both refer to a fuel injection control computer. There would be no need for it on a carb'd 350

It is probably still there behind the glove box but disconnected.

Have you tried a new relay?
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Old 03-12-2012, 01:00 PM   #13
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Okay thanks. Yes replaced the relays. It's starting to look like I am going to have to trace a ton of wires =/ I was hoping it was something like the ECM b/c so many have had the same problem and replaced that and it fixed it all but they have Jeep engines and I don't.
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Old 03-12-2012, 02:09 PM   #14
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Quote:
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Well I currently have my distributor wired from my battery b/c I was having the cranking issues so if I disconnect the positive, I shut down my distributor. I have seen something about a PCM and ECM...any advice what are they/where are they? As I said, I am not a mechanic so every bit of help is appreciate. I'm a frustrated mom trying to help my teen son for 6 weeks now.
Won't matter. Even though the battery is disconnected, the terminal cable should still be HOT from the alternator providing power to it. It's just not charging anything.
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Old 03-12-2012, 02:29 PM   #15
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What do you suggest?
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Old 03-12-2012, 02:32 PM   #16
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When I unplugged the battery cable, the Jeep died. Since then I've replaced the alternator and the battery still isn't charging or receiving a charge...I'm a little lost at this point.
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Old 03-12-2012, 03:55 PM   #17
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Your alternator might be hooked up incorrectly, or your wiring is faulty somewhere in the mix. I would begin to trace out the wires coming off of the back of the alternator to see if the wiring is frayed or broken somewhere between the alternator and the battery.

It's not a difficult system to understand, it's just the tracing part that can get tricky.
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Old 03-12-2012, 03:55 PM   #18
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When I unplugged the battery cable, the Jeep died. Since then I've replaced the alternator and the battery still isn't charging or receiving a charge...I'm a little lost at this point.

Have you tried a new wire between the battery and alternator?
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Old 03-12-2012, 03:58 PM   #19
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That means the ignition is running of the alternator all the time instead of the battery.
This is how it should run when all is functioning properly. The battery is only there to start the vehicle and act as a filter against voltage spikes, once the engine is running the alternator provides sufficient power to the Jeeps entire electrical system.
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Old 03-12-2012, 04:05 PM   #20
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This is how it should run when all is functioning properly. The battery is only there to start the vehicle and act as a filter against voltage spikes, once the engine is running the alternator provides sufficient power to the Jeeps entire electrical system.

I saw I typed that backwards after I posted it and was editing it as you quoted it...
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Old 03-12-2012, 04:50 PM   #21
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I have traced the wires from alternator to battery and all over. I'm going to look at the wires again. There was a breaker on the wire from alternator to battery. I took that off and put a fusible link in place b/c I couldn't find that breaker anywhere. I'm wondering if I should just go ahead and replace the wires from the alternator to the battery. I'm also wondering if I should replace my battery even though it tested good. Should my main focus be on the wires between the alternator and the battery?
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Old 03-12-2012, 10:04 PM   #22
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Get a volt meter and see that the battery has 12+ volts, then start the engine, fast idle and check the voltage, it should be 13.4+ up to 15 if not it not going to charge. check the large wire coming out of the alt. also.
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Old 03-12-2012, 10:45 PM   #23
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Okay I'll check tomorrow. Just curious, what role could my starter selenoid be playing in this situation...any?
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Old 03-12-2012, 11:31 PM   #24
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Ohm out your ground cables. Start with the negative battery cable. Then ohm out your ground cable from engine block to frame. While your down there check out the connections.

Remember to remove the cables. So you are only ohming out the cables. 5 ohms and under is good.
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Old 03-13-2012, 07:57 AM   #25
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Also are your dash gauges working?
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Old 03-13-2012, 07:38 PM   #26
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A friend of ours has tested the wires from alt to relay and back. He said they are good. We have not tested the starter...could the starter play a role in this? Cleaned the grounds on the block and firewall didn't help. New battery and it drained it too! My maint. gages work. Any ideas on a new direction?
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Old 03-13-2012, 07:57 PM   #27
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Quote:
Originally Posted by Mburkey View Post
I believe it's hooked up right. It was running fine and then died and wouldn't crank. The relay is not working on crank. Temporarily we wired up a switch inside Jeep so it's always on (hot wire), so we have to use the switch to turn it off. With that switch it cranks but now the battery won't hold a charge.
So the key wont crank the engine?

There is an energizer wire for the alt. thats on when the key is at run. If for some reason your energizer wire doesn't get power, the alternator will not produce a charge. This could also explain why it bench tested good.

10v sounds like the battery voltage while the jeep is running. I also have a 350 conversion. You might have burned out the ignition switch that rests on top of the steering column and attaches via a rod to the ignition key mechanism.

Original Replacement Parts J3250575 - OEM Ignition Switch for 76-95 Jeep® CJ & Wrangler with Tilt Wheel - Quadratec


So the alternator works Energizes creating a magnetic field. That wire comes from power on the Run position of the ignition key.
Then you have a charging wire to the battery and a power wire for the stater.
My first thought is that its not energizing. If it does not energize then no magnetic field is created and induction can not occure.


If its also the case that the key wont turn over the engine, then check this switch, its on the steering column under the dash. On top.
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Old 03-14-2012, 12:40 AM   #28
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We temporarily wired the distributor to the battery instead of the relay and ran a switch inside Jeep to use for crank and for kill. Until then, I did not have any battery charging issues, I only had crank issues. My son was backing into the driveway and Jeep died and would not crank again. With some quick looking around we could not figure out why relay wasn't working and replaced relay but still wouldn't work so that's why we wired it up to the battery and switch. This fixed the crank problem, lol but now I have the battery problem. How likely is it that the distributor wired to my battery is pulling it down or keeping it from charging. How likely is it that my original cranking problem (along with stalling on acceleration-intermittent basis, poor idle, hesistation-intermittent) is related to a Cam Position Sensor problem or a Crank Position Sensor problem? I'm thinking since I did not have a battery/alternator type problem before, I should wire the distributor back to the relay and then troubleshoot the crank problem. Can I have a CAM or CPS problem and still crank and run the Jeep but with rough running? When I have distributor wired to my relay I go from 12v to 8v which I read the resistor in the distributor is designed to do that but I should have a bypass wire of sorts that should bring it back to 12v. At this point I'm wondering if I should replace the wire harness in distributor, or the CAM, or the CPS after I wire my distributor back to the relay. Thanks for staying with me. I am trying very hard to learn about this engine and get a general idea of how things work. I am a Mental Health Therapist, not a mechanic nor do I have in-depth knowledge of engines. This is a new journey...
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Old 03-14-2012, 07:09 AM   #29
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voltages

Having difficult with understanding what you mean when you say it won't crank but you can turn it over. Should be the same thing.

Starting with the battery. The battery should be 12.7 volts when in its sitting, fully charged. It should go to 14.4 volts when running and being charged. It should not drop below 10v when cranking.

Except for the fact that the alternator may not have charged the battery, the alternator and the battery cranking are totally independent. You can remove the alternator and the vehicle should start and run if the battery is charged.

Alternator: The alternator is a 3 Phase, A/C (alternating current) generator. There is a full wave, 3phase bridge rectifier inside that rectifies the 3 phase A/C current to a pulsating DC current. However, there is only output when there is a field current to energize the generation system inside the alternator.

The field current is supplied from different sources on difference alternators. Some are internally energized. On those there is a regulator inside the alternator. The alternator has enough residual generation to activate the regulator. It then applies field current until the alternator output is 14.4 volts. It supplies enough voltage to the field, up to 14.4 volts, to make that happen.

In the older alternators the regulator was on the side of the fender well and could be relay operating or solid state.

On the Jeep Wrangler, I understand, that regulator is inside the ECM module. If it goes bad, then the alternator won't put out current to charge the battery. There should be a smaller wire going to the alternator. That is the field for the alternator and should have voltage on it when the vehicle is running. If not, then the ECM is bad.

The first thing I would do is work with the battery. Get a charger and charge the battery up to full voltage. Then see if the vehicle will start and run. If not, then you have a problem with the starting section of the vehicle, separate from the battery/alternator. You still might have an alternator problem, but it isn't causing the starting problem.

If it will start and run with a fully charged battery, then you have a charging problem. You can replace the ECM if that is the problem, or you can replace the alternator with one that is the same physically but has an internal regulator.

I am flying pretty blind here as I could not understand your real problem from the way it was described.
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Old 03-14-2012, 08:20 AM   #30
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Okay I apologize b/c my lack of terms and knowledge I am having a hard time explaining it but I do have several people who have knowledge helping me and they are stumped too b/c in theory everything should be working as it sits. My original problem was: the Jeep died while my son was driving and it wouldn't crank back up. It would however make the noise like it was trying but would never catch (so that's what I meant by it will turn over but not fully crank). We replaced the dist. cap, coil, and ignition module. It still would not crank. I keep having parts store charge my battery and keep testing/trying new things. The battery drains out in a very short time. The alt is now new. Could I be having this charging problem b/c we wired the distributor straight to the battery and bypassed the relay? It's either not charging or something is drawing it down. The old alt bench tested good. Then we tested it inside the Jeep and it tested at 10.4 so we replaced it. Now the new alt is testing inside the Jeep at 11.8, still not enough. I'm wondering if I need to wire that distributor back to the relay and then work on the original cranking problem. Since this has been converted to the Chevy 350 I didn't think I was using an ECM. I have a black plug at the top of the firewall in the center with nothing plugged into it.

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