No charging after Check Gauges light and p1682 code
11-21-2019, 05:25 PM
#16
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Year: 96
Model: Cherokee (XJ)
Engine: 4.0
It seems to me it might be the cheapest "test" to see if that is the issue...and could be considered as a reliability upgrade
cheaper than ordering a "rebuilt" PCM anyway, which would be another way to proceed
@ OP I would Google Search "external voltage regulator Jeep cherokee XJ" and see what you come up...
lol..I will do it for you now and edit back in a link if i find one!
I checked and there is quite a lot of info..sorry, cant help myself, as a parent, this bought a smile to my face
..clearly its a common problem..when you done fix it, git yourself a proper haircut too lol
Last edited by awg; 11-21-2019 at 05:41 PM.
11-21-2019, 05:33 PM
#17
Banned
Just do it.. Nike-swoosh
Given the nature of this members problem. I totally agree with bypassing the PCM regulator.
Given the nature of this members problem. I totally agree with bypassing the PCM regulator.
Last edited by Noah911; 11-21-2019 at 05:36 PM.
11-22-2019, 05:27 AM
#19
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Year: 1999
Model: Cherokee (XJ)
Engine: 4.0
At this point, I'm about to have it ran by my local jeep dealership for a diagnostic check. The problem is looking more and more computer related. A friend of mine with auto background had help to diagnose with me what was going on where we basically started checking off what was wrong. Definitely it's a cold start problem, as the vehicle will not code when it was warm. There is some sort of shorting question since we have done the terminal test when we took off the positive clamp and left the negative on and no resistance. Also, at the time it just so happened to CHECK CLUSTER code while he was there and we checked the voltage right at the battery and the clamps, both read 12.5v at the multimeter while the gauge cluster was pegged all the way to the left at 9v. So something is obviously telling the cluster to tell the sensor and/or the cluster to not read voltage correctly. At this point, it is very likely a ECM issue. But why get just a voltage regulator when you could still run the risk of it being in the ECM? Why not just get a new ECM and be done with it? This is why I am considering a diagnostic test at the dealership. If they can run it down to the ECM the faster I can get to shopping for a new ECM and be done. Hopefully it isn't a harness issue because then we're practically at square one and to start chasing this down. Unless someone can think of a way to test if it is the voltage regulator without the test being install a voltage regulator kit. At that point, I might as well buy a new ECM. Or a junkyard ECM and troubleshoot whatever problems that new junker ECM might have also.
11-22-2019, 08:11 AM
#21
CF Veteran
It's your call. I got a good pcm from Advance for $125 or so, cardone rebuilt. Not for a regulator issue, but it did work good and also it fixed a transmission hot shifting issue which was a completely unexpected benefit.
As far as the regulator, I did the swap as mentioned in post 11, and I still run the external reg with the new pcm. I like it because it charges at a higher voltage that the pcm did, 14.4 or so cold. You do have to add a dummy load to the old field wires to make the pcm think it's still in control. Other than that it's textbook to install if you have some medium electrical skills, know your way around a multimeter etc.
I have added high output headlights which do draw more than stock, and at idle with everything on, heater on high and fog lights, the draw seems to exceed the stock alternator output, and the voltage drops until I turn something off like the fog lights. But that problem was also with the pcm reg. too.
As far as the regulator, I did the swap as mentioned in post 11, and I still run the external reg with the new pcm. I like it because it charges at a higher voltage that the pcm did, 14.4 or so cold. You do have to add a dummy load to the old field wires to make the pcm think it's still in control. Other than that it's textbook to install if you have some medium electrical skills, know your way around a multimeter etc.
I have added high output headlights which do draw more than stock, and at idle with everything on, heater on high and fog lights, the draw seems to exceed the stock alternator output, and the voltage drops until I turn something off like the fog lights. But that problem was also with the pcm reg. too.
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Noah911 (11-22-2019)
11-22-2019, 07:29 PM
#22
Banned
I still say full field the alternator. Especially, based off your thought process of wanting to jump to replacing the PCM. I mean, the way I see it. if you are going to go ahead and want to preemptively condemn the PCM. Then why not? It would only serve to help. What if you replaced the PCM and it was not the reason? You would get a somewhat expensive non-solution to the problem. If you full field it.. you would know better wether or not it is related to the PCM.
If it is because of the regulator function of the PCM? You may want to bypass it with an external regulator. Alternatively, you could replace the PCM especially should the other issue still persists.. of your gauges not reading the voltage correctly. However, the voltage gauge may correct itself when you bypass things with an external regulator? I don't know if it would, but it might if you fool the PCM how it is described in the post above? Or, it may just remain reading wrong like that.. but actually have a correct regulated charge going to your battery. It would just be something to keep in mind to know at that point. Unless that were to bother you enough and make you want to also replace your PCM to resolve that nuance. If it is always starting and holding a charge though.. It wouldn't 'need' to be fixed. I'd probably want that fixed myself though.
Having the faulty reading at your voltage gauge like that does make me think it really could possibly be other reasons though (maybe I am overthinking things bases off my own past experience). 'Voltage drop' occuring elsewhere in other circuits does strange things. A voltage drop somewhere being the reason for your charging issue may also effect that gauge.
If you full field it and the charging issue still remains. You would know it was not the PCMs fault, and it is due to something else. Possibly being related to having voltage drop?
If you are thinking to replace the PCM anyways. What would it matter about the risks involved in full fielding the alterator to have to worry any about damaging the PCM?
If you did not want to worry about the risks or hastle of trying to full field it.. By-passing the PCM with an external regulator right from the start is not a bad idea. Even if you end up replacing the PCM with a new one, you would still end up with a better way of regulating the alternators charging. The plus to this is that it is also another means to test and see if it is actually a fault due to the PCM. An external regulator is comparatively inexpensive.. particularly should you pick one up from the junkyard.
I would recommend to full field it and see.. If the charging measured at the battery jumps up to 15+ VOLTS. Your problem is solved right there... New external regulator. Or, a PCM replacement.
Full Fielding:
On Chrysler systems, there should be two field terminals on the back of the alternator. Battery power is applied to one terminal—technically, it doesn't matter which one. For yours with a voltage regulator within the PCM controlling the alternators charge, this toggles the other field terminal; that is, it switches the other field terminal on and off to ground. The longer this field terminal is grounded, the longer the alternator charges, and vice versa.
You can isolate the alternator from the PCM regulator simply by grounding the ground-side field terminal—the one wired leading from the PCM regulator. Does the alternator charge? If it does, then either the ground circuit is open, or the PCM voltage regulator function has failed.
You can make another simple system check if you wanted to by connecting a low-current test light to the ground-side field terminal. Then, start the engine. If the PCM regulator is toggling the ground side of the field on and off, then the test light should blink. If it is not, this indicates the PCM is at fault.
It is also possible to isolate the alternator on a Chrysler vehicle.. if you wanted to do it this way instead. By disconnecting both field wires from the back of the alternator. Jumper battery power to one of the field terminals, and then ground the other one. The advantage here is that bypassing both sides of the field circuit completely separates the field circuit from the rest of the electrical system. What’s more, the alternator rotor doesn’t care which direction field current flows through it—as long as it flows. So for the moment, you needn’t worry about which field terminal is hot or which is ground.
Full fielding the alternator with these tests mentioned above means the alternator operates uncontrolled on a vehicle laden with electronics. So, exercise appropriate caution. For example, be sure all electrical accessories are shut off beforehand. Then, connect a digital voltmeter to the battery. If you are isolating it as in the last method I mentioned above.. have your jumper wires securely connected to the alternator field terminals before you start the engine. Then, start the engine and connect the jumpers to power and/or ground as needed—but only long enough to see if the alternator charges. Disconnect the jumper wire the moment you see a reaction on the digital voltmeter. No reaction of 15+ VOLTS seen on your multimeter means it is probably not the PCM.
I feel confident of the information I am telling you.. Still, I would recommend for you to verify the field terminals and such on the alternator to make sure it is as I say. Any member here who knows and is also reading this should tell of any inaccuracies if they should see them too.
That is my extra cents.
I hope you are able to find the reason(s), and get it fixed back up and running good.
If it is because of the regulator function of the PCM? You may want to bypass it with an external regulator. Alternatively, you could replace the PCM especially should the other issue still persists.. of your gauges not reading the voltage correctly. However, the voltage gauge may correct itself when you bypass things with an external regulator? I don't know if it would, but it might if you fool the PCM how it is described in the post above? Or, it may just remain reading wrong like that.. but actually have a correct regulated charge going to your battery. It would just be something to keep in mind to know at that point. Unless that were to bother you enough and make you want to also replace your PCM to resolve that nuance. If it is always starting and holding a charge though.. It wouldn't 'need' to be fixed. I'd probably want that fixed myself though.
Having the faulty reading at your voltage gauge like that does make me think it really could possibly be other reasons though (maybe I am overthinking things bases off my own past experience). 'Voltage drop' occuring elsewhere in other circuits does strange things. A voltage drop somewhere being the reason for your charging issue may also effect that gauge.
If you full field it and the charging issue still remains. You would know it was not the PCMs fault, and it is due to something else. Possibly being related to having voltage drop?
If you are thinking to replace the PCM anyways. What would it matter about the risks involved in full fielding the alterator to have to worry any about damaging the PCM?
If you did not want to worry about the risks or hastle of trying to full field it.. By-passing the PCM with an external regulator right from the start is not a bad idea. Even if you end up replacing the PCM with a new one, you would still end up with a better way of regulating the alternators charging. The plus to this is that it is also another means to test and see if it is actually a fault due to the PCM. An external regulator is comparatively inexpensive.. particularly should you pick one up from the junkyard.
I would recommend to full field it and see.. If the charging measured at the battery jumps up to 15+ VOLTS. Your problem is solved right there... New external regulator. Or, a PCM replacement.
Full Fielding:
On Chrysler systems, there should be two field terminals on the back of the alternator. Battery power is applied to one terminal—technically, it doesn't matter which one. For yours with a voltage regulator within the PCM controlling the alternators charge, this toggles the other field terminal; that is, it switches the other field terminal on and off to ground. The longer this field terminal is grounded, the longer the alternator charges, and vice versa.
You can isolate the alternator from the PCM regulator simply by grounding the ground-side field terminal—the one wired leading from the PCM regulator. Does the alternator charge? If it does, then either the ground circuit is open, or the PCM voltage regulator function has failed.
You can make another simple system check if you wanted to by connecting a low-current test light to the ground-side field terminal. Then, start the engine. If the PCM regulator is toggling the ground side of the field on and off, then the test light should blink. If it is not, this indicates the PCM is at fault.
It is also possible to isolate the alternator on a Chrysler vehicle.. if you wanted to do it this way instead. By disconnecting both field wires from the back of the alternator. Jumper battery power to one of the field terminals, and then ground the other one. The advantage here is that bypassing both sides of the field circuit completely separates the field circuit from the rest of the electrical system. What’s more, the alternator rotor doesn’t care which direction field current flows through it—as long as it flows. So for the moment, you needn’t worry about which field terminal is hot or which is ground.
Full fielding the alternator with these tests mentioned above means the alternator operates uncontrolled on a vehicle laden with electronics. So, exercise appropriate caution. For example, be sure all electrical accessories are shut off beforehand. Then, connect a digital voltmeter to the battery. If you are isolating it as in the last method I mentioned above.. have your jumper wires securely connected to the alternator field terminals before you start the engine. Then, start the engine and connect the jumpers to power and/or ground as needed—but only long enough to see if the alternator charges. Disconnect the jumper wire the moment you see a reaction on the digital voltmeter. No reaction of 15+ VOLTS seen on your multimeter means it is probably not the PCM.
I feel confident of the information I am telling you.. Still, I would recommend for you to verify the field terminals and such on the alternator to make sure it is as I say. Any member here who knows and is also reading this should tell of any inaccuracies if they should see them too.
That is my extra cents.
I hope you are able to find the reason(s), and get it fixed back up and running good.
Last edited by Noah911; 11-23-2019 at 12:49 PM.
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awg (11-22-2019)
11-23-2019, 05:28 AM
#24
CF Veteran
No offense, Noah, but, Baloney. What do they say on those TV court shows? If you repeat something wrong enough it doesn't make it true?
Full fielding the alternator is an old school test that should not be done on modern vehicles unless you want to risk roasting your electronics. It's also stupid, no offense Noah, because it's inconclusive. You would not know what voltage to expect! Noah? Any idea what voltage he should expect? Moreover, with the advance of electronics, you can just drive to any big box and have them show you a diode test and output test and test the whole system FOR FREE with a non damaging tester.
Now, this is from the 98 Jeep FSM regarding charging system testing. They say to use a tester that has a DC current probe and a carbon rehostat load. (sort of like what I said the big box stores do.) Notwithstanding they offer the following
"CAUTION; WHEN ADJUSTING THE REHOSTAT LOAD, DO NO ALLOW VOLTAGE TO RISE ABOVE 16 VOLTS. DAMAGE TO THE BATTERY AND ELECTRICAL SYSTEM COMPONENTS MAY RESULT."
and this:
"CAUTION: DO NOT CONNECT THE JUMPER GROUND WIRE TO GENERATOR FIELD SOURCE FIELD TERMINAL. DAMAGE TO ELECTRICAL SYSTEM COMPONENTS MAY RESULT."
Full fielding the alternator is an old school test that should not be done on modern vehicles unless you want to risk roasting your electronics. It's also stupid, no offense Noah, because it's inconclusive. You would not know what voltage to expect! Noah? Any idea what voltage he should expect? Moreover, with the advance of electronics, you can just drive to any big box and have them show you a diode test and output test and test the whole system FOR FREE with a non damaging tester.
Now, this is from the 98 Jeep FSM regarding charging system testing. They say to use a tester that has a DC current probe and a carbon rehostat load. (sort of like what I said the big box stores do.) Notwithstanding they offer the following
"CAUTION; WHEN ADJUSTING THE REHOSTAT LOAD, DO NO ALLOW VOLTAGE TO RISE ABOVE 16 VOLTS. DAMAGE TO THE BATTERY AND ELECTRICAL SYSTEM COMPONENTS MAY RESULT."
and this:
"CAUTION: DO NOT CONNECT THE JUMPER GROUND WIRE TO GENERATOR FIELD SOURCE FIELD TERMINAL. DAMAGE TO ELECTRICAL SYSTEM COMPONENTS MAY RESULT."
11-23-2019, 05:44 AM
#25
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Join Date: Mar 2016
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Year: 96
Model: Cherokee (XJ)
Engine: 4.0
Moreover, with the advance of electronics, you can just drive to any big box and have them show you a diode test and output test and test the whole system FOR FREE with a non damaging tester.
Now, this is from the 98 Jeep FSM regarding charging system testing. They say to use a tester that has a DC current probe and a carbon rehostat load. (sort of like what I said the big box stores do.) Notwithstanding they offer the following"
Now, this is from the 98 Jeep FSM regarding charging system testing. They say to use a tester that has a DC current probe and a carbon rehostat load. (sort of like what I said the big box stores do.) Notwithstanding they offer the following"
11-23-2019, 05:51 AM
#26
CF Veteran
11-23-2019, 05:58 AM
#27
CF Veteran
That's good advice. Myself, and I say this not because I want it to 'make me right', but just as for my background, I would not hold myself out to be an "Auto Electrician" but I have been a licensed residential electrician, well, next year will be my 25 year licensed by the City. Oh and I have both AAS and BS degrees in Electrical Technology and Electrical Engineering Technology from the State University of New York, respectively.
11-23-2019, 11:12 AM
#28
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Year: 1989
Model: Comanche (MJ)
Engine: 4.0
Hey thanks BruceB for the response!
So I'm really trying to focus on diagnostic checking the vehicle to get more of an idea of where the problem is before I go around checking every ground and all continuity in all the many harness to check at. I do know the p1682 code has already been tied to multiple areas but I'm getting more of a vibe that it is the voltage regulator is the culprit after speaking to a few folks about the situation for the p1682. I do want to reemphasize that the vehicle does charge the battery under certain conditions (i.e. the vehicle needs to be warmed up for a bit, then the ignition needs to be turned off and on several times until the voltage gauge indicates it is getting ~13v at which point I know the alternator is giving charge to the battery).
So I'm really trying to focus on diagnostic checking the vehicle to get more of an idea of where the problem is before I go around checking every ground and all continuity in all the many harness to check at. I do know the p1682 code has already been tied to multiple areas but I'm getting more of a vibe that it is the voltage regulator is the culprit after speaking to a few folks about the situation for the p1682. I do want to reemphasize that the vehicle does charge the battery under certain conditions (i.e. the vehicle needs to be warmed up for a bit, then the ignition needs to be turned off and on several times until the voltage gauge indicates it is getting ~13v at which point I know the alternator is giving charge to the battery).
Also, P1682 is NOT a charging issue. https://www.engine-codes.com/p1682.html. Given that you said working the key back-n-forth can recreate or fix the issue, I would suspect the ignition switch. When you have a no-charging issue with the engine running, check if you have full battery voltage to the alternator. As mentioned, one wire should be at battery voltage and the ECM controls the ground side of it. If you don't then your problem is not the alternator or the ECM. Measuring the ECM controlled side with your meter, you should see varying voltage depending on how much charging the ECM is commanding. Close to zero if commanding it to charge, and battery voltage if the ecm is not commanding it to charge.
Last edited by lawsoncl; 11-23-2019 at 11:18 AM.
11-23-2019, 11:40 AM
#30
Banned
Nope.. It did not burn. It is not on fire right now. That's how long it took me what like 5 minutes or something?
This is also not the first time I have full fielded an alternator either.
This is also not the first time I have full fielded an alternator either.
Last edited by Noah911; 11-23-2019 at 02:45 PM.