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View Full Version : Diagnosing an Electrical issue (aka A series of unfortunate events, LoL)



d0nt_h8
01-10-2010, 03:19 PM
Ok, this entire thing starts back on October 01, 2009. I was on the fwy with the Cherokee and driving 70 when I had a right-front wheel come off at speed. Luckily the thing didn't roll and just caused some sparks on the freeway.

As a result, I replaced the rotors & wheel. This was fine for about 2 minutes. I started driving and heard something on my rig 'shift'. I couldn't tell what it was or where when I inspected it. A little later I was looking inside the engine well and noticed a broken motor mount. So I replaced THAT. Once the motor mount was replaced the rig ran fine, but I started getting an 'error 41' diagnostic code which apparently means " An open or shorted condition detected in the generator field control circuit." This also drained my battery.

At this point I took the rig to a mechanic. He stated that my 'alarm indicator light' was the culprit, and disconnected it. It then ran fine & didn't run down the battery.

The problem now is that the front windshield wipers no longer work. WHAT THE HELL, LoL.. :stars:

I had another guy tell me it was just the wiper switch, but I'm unsure. Anyone suspect the timing of this other than me? Oh and to top it off, my battery was dead again this morning. All after taking it out & driving it around 3 counties just yesterday. It did have a momentary start problem yesterday early too, then started.. I'm at a loss as to where to go next.

4.3LXJ
01-11-2010, 09:59 AM
This is the place where in chasing electrical gremlins that you need a good meter. I got a good one from Sears for this purpose and as a back up for my others on the job a while back. The cool thing about it is that in not only measures volts and ohms, but will measure both AC and DC amps. I had one like this and it turned out to be the alternator. found it in less than five minutes by following the current draw with the amp clamp. I suspect your switch may be bad, but there are some things to check first. The wiper motor gets current all the time when the key is on for the park function. I would just unplug it and start checking that with a test light if nothing else. And if you had that meter you could see if there is a current draw there too while you're at it.

d0nt_h8
01-11-2010, 10:45 AM
This is the place where in chasing electrical gremlins that you need a good meter. I got a good one from Sears for this purpose and as a back up for my others on the job a while back. The cool thing about it is that in not only measures volts and ohms, but will measure both AC and DC amps. I had one like this and it turned out to be the alternator. found it in less than five minutes by following the current draw with the amp clamp. I suspect your switch may be bad, but there are some things to check first. The wiper motor gets current all the time when the key is on for the park function. I would just unplug it and start checking that with a test light if nothing else. And if you had that meter you could see if there is a current draw there too while you're at it.

Dude- thanks for the solid info- I'm picking up a meter today! I'll let everyone know the outcome.

d0nt_h8
01-24-2010, 05:08 PM
...after all the checking it DID turn out to be a battery- hey better that than something really expensive! :thumbsup:

Melissa
01-24-2010, 08:34 PM
...after all the checking it DID turn out to be a battery- hey better that than something really expensive! :thumbsup:

Much better than something really expensive.

How old was your other battery?

Melissa
01-24-2010, 08:50 PM
The reason I am asking......................

last year I went through my jeep throwing an error 41 code, which in my 93 is the Alternator field circuit. I had my alt out three different times and it tested good, and my battery I replaced 3 different times because it was not passing, I was stumped because every battery I replaced was for one that was brand new from the parts store. Turns out after the fourth time I had my alt out and went to a fourth parts store to have it tested, he hooked it up, it passed again, but he stopped and said wait a minute and tried it again, it still passed but he said something is wrong...................20 minutes and $15 dollars later he replaced the brushes in it and I went on my way.

I just thought I would throw that out there because your jeep threw a 41 code and even though my alt passed all the tests it was still the problem, not my battery.

I hope it is just your battery, but if it happens again, I would take a hard look at your alternator.

Thats just my 2 cents

rguignard
01-25-2010, 06:36 AM
i would ck the alt as well if the diodos ( i suck at spelling ) are bad it will ck good but its still bad. as far as the wipers go ck for power and allways ck the fuse FIRST !!!! dont ask how i know about that one :smiley-laughing021: did you have it done when the tire came off ?

BlueXJ
01-25-2010, 09:02 AM
This is what I think the chain of events seem to be. First when the tire came off the front probably slammed into the ground, breaking the motor mount. The broken motor mount caused the alternator to, along with the motor, shift and the alternator shorted against the unibody. Once this happened it continued to give insufficient re-charge to the battery causing premature failure.
You repaired or replaced all components except the alternator and the wiper switch which probably went bad from usage at less than 12 volts. So by using this chain of events after you replace the switch and alternator you should be at the end of the problem except one. What caused you to lose the wheel in the first place???

W.O.R.P.Offroad
01-26-2010, 07:09 PM
i have had sim electrical issues alt, batt, and starters failin all the time. i upgraded all my batt and alt cables and never had another problem.

d0nt_h8
01-27-2010, 05:59 PM
The reason I am asking......................

last year I went through my jeep throwing an error 41 code, which in my 93 is the Alternator field circuit. I had my alt out three different times and it tested good, and my battery I replaced 3 different times because it was not passing, I was stumped because every battery I replaced was for one that was brand new from the parts store. Turns out after the fourth time I had my alt out and went to a fourth parts store to have it tested, he hooked it up, it passed again, but he stopped and said wait a minute and tried it again, it still passed but he said something is wrong...................20 minutes and $15 dollars later he replaced the brushes in it and I went on my way.

I just thought I would throw that out there because your jeep threw a 41 code and even though my alt passed all the tests it was still the problem, not my battery.

I hope it is just your battery, but if it happens again, I would take a hard look at your alternator.

Thats just my 2 cents





"O ye of great premonitions" lol.... guess what-

went out this morning to take the dog to a local park, and nuthin... no turnover, no clickie, no lights.. :mad0090: I love working on my Jeep.. but this kind of thing drives me insaaane.....:mad: Ok, so you said brushes in the alternator? What did he say was actually wrong with the existing brushes.. especially if it was passing on the test?

...this kind of thing would be interesting to just take my time & figure out if I didn't have a day job, lol... damn..

d0nt_h8
01-27-2010, 06:08 PM
This is what I think the chain of events seem to be. First when the tire came off the front probably slammed into the ground, breaking the motor mount. The broken motor mount caused the alternator to, along with the motor, shift and the alternator shorted against the unibody. Once this happened it continued to give insufficient re-charge to the battery causing premature failure.
You repaired or replaced all components except the alternator and the wiper switch which probably went bad from usage at less than 12 volts. So by using this chain of events after you replace the switch and alternator you should be at the end of the problem except one. What caused you to lose the wheel in the first place???


You know, when taking a step back you probably dead-on about this chain of events.. But if the alt. shorted against the body, would I not get a low meter reading? Nothing abnormal electrically has been indicated other than that brief error code 41.

Regarding the wheel, there was apparently a couple of hairline fractures in the wheel studs. I have kept them tight forever.. the only thing I can think of that put it past the point of no return would maybe be hitting a curb or something at a higher speed.. but my wife would have told me that... maybe it was from the desert running of the kid who butchered my fenders finally causing them to fail.. I was just driving on the fwy at the time.. Never ever found that wheel lol, but a look at it showed some were rusted about 1/2 way through the stud showing they had been cracked.. I'm just glad it was ME driving.. I kicked up sparks until I stopped, lol :eek:

Melissa
01-28-2010, 05:25 AM
"O ye of great premonitions" lol.... guess what-

went out this morning to take the dog to a local park, and nuthin... no turnover, no clickie, no lights.. :mad0090: I love working on my Jeep.. but this kind of thing drives me insaaane.....:mad: Ok, so you said brushes in the alternator? What did he say was actually wrong with the existing brushes.. especially if it was passing on the test?

...this kind of thing would be interesting to just take my time & figure out if I didn't have a day job, lol... damn..


What I remember was the last place I had my alt tested the guy said yup it's passing, but he took the time to test it more than once and really watch what my alt was doing. He tore into it, looked at the brushes and said this is your problem, your brushes are going bad. I don't know exactly what the problem with the brushes were, or what they even do, but it was a $15 dollar fix and now over a year later my alt is still working great. That is the reason I mentioned it, I went through hell trying to figure out what the heck was going on with my Jeep, why I kept getting stranded, why all the brand new batteries were "going bad", and where the short was that was causing all my problems. Yours sound almost identical to what I went through, thats why I thought you might benefit from me saying something. I really was hoping it was just your battery, there much easier to get to and change....lol

YellowSub2000
01-28-2010, 06:15 AM
This is what I think the chain of events seem to be. First when the tire came off the front probably slammed into the ground, breaking the motor mount. The broken motor mount caused the alternator to, along with the motor, shift and the alternator shorted against the unibody. Once this happened it continued to give insufficient re-charge to the battery causing premature failure.
You repaired or replaced all components except the alternator and the wiper switch which probably went bad from usage at less than 12 volts. So by using this chain of events after you replace the switch and alternator you should be at the end of the problem except one. What caused you to lose the wheel in the first place???

I was thinking and about to say the same thing, but you put it in better words than I would have. Good Job!

YellowSub2000
01-28-2010, 06:28 AM
What I remember was the last place I had my alt tested the guy said yup it's passing, but he took the time to test it more than once and really watch what my alt was doing. He tore into it, looked at the brushes and said this is your problem, your brushes are going bad. I don't know exactly what the problem with the brushes were, or what they even do, but it was a $15 dollar fix and now over a year later my alt is still working great. That is the reason I mentioned it, I went through hell trying to figure out what the heck was going on with my Jeep, why I kept getting stranded, why all the brand new batteries were "going bad", and where the short was that was causing all my problems. Yours sound almost identical to what I went through, thats why I thought you might benefit from me saying something. I really was hoping it was just your battery, there much easier to get to and change....lol

The brushes for an alternator serve a similar purpose as brushes in an electric motor. They provide a connection to the armature (shaft) for the current to travel when its collected from the rotation. Since the armature is spinning, the connection cannot be a permanent one, hence the "Brushes". A wearable composite of metal that is made to maintain contact with the armature. Brushes are spring loaded, once worn or broken the contact becomes compromised, providing less power. The starter motor would also have brushes, for thoughts. Hope this explains their purpose a little bit.

http://electronics.howstuffworks.com/motor5.htm for another outlook on it.

Mudderoy
01-28-2010, 08:56 AM
I'm amazed at the engineering of my Jeep. 150k miles and I'm still on the same alternator. I'm thinking about switching it out for a Dakota(?) alternator to get the higher amperage for my off road lights and winch.

d0nt_h8
01-28-2010, 03:42 PM
....there is some great info here.. thanks! So, can anyone tell me WHY none of the readings would be low- either during diagnostics or just basic driving around? I got no funky readings....

Then nothing.

rguignard
01-28-2010, 04:20 PM
....there is some great info here.. thanks! So, can anyone tell me WHY none of the readings would be low- either during diagnostics or just basic driving around? I got no funky readings....

Then nothing.

yep its working good becouse the diodes are bad would be my guess. if you think of a diodes as a one way ck valve it lets power go one way but not the other. now yours are letting power go both ways thats why you getting a dead battery its got a drain on it at all times. just my 2 cents

Melissa
01-28-2010, 04:48 PM
The brushes for an alternator serve a similar purpose as brushes in an electric motor. They provide a connection to the armature (shaft) for the current to travel when its collected from the rotation. Since the armature is spinning, the connection cannot be a permanent one, hence the "Brushes". A wearable composite of metal that is made to maintain contact with the armature. Brushes are spring loaded, once worn or broken the contact becomes compromised, providing less power. The starter motor would also have brushes, for thoughts. Hope this explains their purpose a little bit.


Makes more sense to me now, thanks

Oh and I did the same on my starter, changed the brushes in it, so much cheaper than buying a new one.




I'm amazed at the engineering of my Jeep. 150k miles and I'm still on the same alternator. I'm thinking about switching it out for a Dakota(?) alternator to get the higher amperage for my off road lights and winch.

So am I for the most part, my alt had over 200K on the original before the brushes were changed




yep its working good becouse the diodes are bad would be my guess. if you think of a diodes as a one way ck valve it lets power go one way but not the other. now yours are letting power go both ways thats why you getting a dead battery its got a drain on it at all times. just my 2 cents

Yup, that was my problem, wish I had learned it this way instead of the way I did :rotfl2:

YellowSub2000
01-28-2010, 06:32 PM
I believe an Alternator from a new Grand has a higher Amp rating also. I believe it's direct bolt in if you take the mount.

d0nt_h8
01-28-2010, 10:23 PM
yep its working good becouse the diodes are bad would be my guess. if you think of a diodes as a one way ck valve it lets power go one way but not the other. now yours are letting power go both ways thats why you getting a dead battery its got a drain on it at all times. just my 2 cents

ohhh ok.. lol.. sometimes it takes me a minute, lol... that just clicked (unlike my starter) with me & makes complete sense... :):thumbsup:

THANKS!

d0nt_h8
01-28-2010, 10:24 PM
I believe an Alternator from a new Grand has a higher Amp rating also. I believe it's direct bolt in if you take the mount.

Now THAT's just a good call.

rguignard
01-29-2010, 06:17 AM
did you get it fixed ? the grand alt isnt a bolt in if i remember right you have to do some mods but it easy stuff if you do it take some pics and post them up :thumbsup:

d0nt_h8
01-30-2010, 05:01 PM
..nope, I get paid Monday.:boohoo: ..but on top of the alt, if that fixes the issue I'm going to add my coil-overs and 4:88s.. sweet! :popcorn:

rguignard
01-30-2010, 08:25 PM
..nope, I get paid Monday.:boohoo: ..but on top of the alt, if that fixes the issue I'm going to add my coil-overs and 4:88s.. sweet! :popcorn:

are you taking the frt springs out and replacing them with the coil-overs ? i would love to do that but im putting my lift on tomorow. are you going to go with a zj alt ? are you doing the gear swap ?

d0nt_h8
01-30-2010, 10:03 PM
are you taking the frt springs out and replacing them with the coil-overs ? i would love to do that but im putting my lift on tomorow. are you going to go with a zj alt ? are you doing the gear swap ?

Yep, I'm going with adjustable coil-overs... installing those at a friend's place.. I've been wanting them for while! I'm not doing the re-gear.. I gots no space! LoL:) I SO miss my spot outside of the city.. I want my shop back!! :sad0147:

heheee

rguignard
01-30-2010, 10:11 PM
Yep, I'm going with adjustable coil-overs... installing those at a friend's place.. I've been wanting them for while! I'm not doing the re-gear.. I gots no space! LoL:) I SO miss my spot outside of the city.. I want my shop back!! :sad0147:

heheee

:smiley-laughing021: i work in a shop and i have full access to it at all times

d0nt_h8
01-31-2010, 12:34 AM
:smiley-laughing021: i work in a shop and i have full access to it at all times

...yeah I knew that part was gonna be irritating when I moved.. now all I can think about is my city bug-out plan, rofl.. after I completely finish with what I wanted to do with my rig, land is the next step.. I will get my damn shop back one way or another :thumbsup:

rguignard
01-31-2010, 08:27 AM
...yeah I knew that part was gonna be irritating when I moved.. now all I can think about is my city bug-out plan, rofl.. after I completely finish with what I wanted to do with my rig, land is the next step.. I will get my damn shop back one way or another :thumbsup:

:thumbsup:

rguignard
01-31-2010, 08:30 AM
Yep, I'm going with adjustable coil-overs... installing those at a friend's place.. I've been wanting them for while! I'm not doing the re-gear.. I gots no space! LoL:) I SO miss my spot outside of the city.. I want my shop back!! :sad0147:

heheee

on your coil-overs are you going to reinforce the upper shock mounts ? or how are you going to mount them ?

d0nt_h8
02-02-2010, 08:18 PM
...ok, good news. Come to find out that after all was said and done, there was a part of the battery cable which (as a result of the prior accident) had shifted and was grounding against the body, causing the failure. I so love it when unexpected repairs have a cheaper than planned solution...

Cables replaced, alt now charging & so far so good.. I say that with, maybe a moment of hesitation.. lol.. I keep waiting for it to happen again! But since I fixed it yesterday, it has held a charge since.. keeping my fingers crossed, LOL

We'll see if she holds!
:D

rguignard
02-02-2010, 08:40 PM
...ok, good news. Come to find out that after all was said and done, there was a part of the battery cable which (as a result of the prior accident) had shifted and was grounding against the body, causing the failure. I so love it when unexpected repairs have a cheaper than planned solution...

Cables replaced, alt now charging & so far so good.. I say that with, maybe a moment of hesitation.. lol.. I keep waiting for it to happen again! But since I fixed it yesterday, it has held a charge since.. keeping my fingers crossed, LOL

We'll see if she holds!
:D

power to ground not good :thumbdown: glad you found it hope thats all :thumbsup: