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Voltage Regulator Issue


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Well, you can use the external regulator or fix it right. Get rid of the 41 code and your charging problem goes away w/o using the external regulator. I think it a wiring problem and something's open in the field wire circuitry. I'd also try cleaning up all the alternator connections and pull the ECU 60-pin connector and clean up both the male and female connectors. The ECU might be bad too, but I don't think so. Do an ohms check across the two field connections.

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Roger, I'd like to fix the problem, but that probably won't happen without tearing apart the harness. The external voltage regulator isn't even charging anymore. I'm tempted to just put my renix style alternator bracket and alt on and rig up a harness. 

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6 hours ago, PFCLeist said:

Roger, I'd like to fix the problem, but that probably won't happen without tearing apart the harness. The external voltage regulator isn't even charging anymore. I'm tempted to just put my renix style alternator bracket and alt on and rig up a harness. 

 

You can basically run the Renix alt as a 1-wire.  I think I had mine switched to the ignition or master disconnect on my old MJ, but I don't believe it needs to be as it's like any other CS-130 and shuts the field off if there's no rotation (or whatever magic goes on there).

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Yeah the old GM alternator jeep used in the 80s with a built in regulator is fairly simple wiring.

My preference would be to figure out the issue with the 93 alternator, but if you can fit the Renix alternator then maybe it’s not an issue you need to mess with. Unless there’s something else wrong with the PCM.

 

 

 

Sent from my iPhone using Tapatalk Pro

 

 

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On 3/6/2018 at 8:47 PM, HOrnbrod said:

Well, you can use the external regulator or fix it right. Get rid of the 41 code and your charging problem goes away w/o using the external regulator. I think it a wiring problem and something's open in the field wire circuitry. I'd also try cleaning up all the alternator connections and pull the ECU 60-pin connector and clean up both the male and female connectors. The ECU might be bad too, but I don't think so. Do an ohms check across the two field connections.

2.5 OHMs engine off, and about 6 running at idle. Cleaned up the ECU connections nice, they weren't bad at all. Even the external regulator isn't charging anymore, which is why I am assuming my new alternator is also bad. 

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5 minutes ago, PFCLeist said:

2.5 OHMs engine off, and about 6 running at idle. Cleaned up the ECU connections nice, they weren't bad at all. Even the external regulator isn't charging anymore, which is why I am assuming my new alternator is also bad. 

 

The 2.5 ohms show the field winding isn't open, so that's good. The code 41 is really just an indication that the ECU isn't seeing the the alt and it's not charging. There are many causes that will flash the 41 code. I'm about out of ideas and at this point would start searching for others (especially early XJ HO owners) who had code 41 and what was their fix.

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  • 2 weeks later...

Just based off the part numbers on RockAuto it looks like the ecu interchange years are '91-'92; '93; and '94-'95.

I've got an ecu out of a '93 XJ Country in a box somewhere. The jeep ran before I parted it out three or four years ago. I hung onto it thinking I'd use it as a spare before I discovered the interchange issues, but I don't really need to hang onto it if I don't need it. It did get plugged into my '91 MJ once while I was doing diagnostics but it wasn't an ecu problem, I'm just adding that cause I don't know what difference there is between them and what effect it may have had on the ecu. 

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How much would it cost for you to part ways with it? It's proving to be difficult to find one around here in junkyards, and they won't sell me one at an auto parts store without a serial number, which of course mine doesn't have, the sticker is worn off. They also want mileage, which I'm sure these computers didn't store. 

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5 hours ago, PFCLeist said:

How much would it cost for you to part ways with it? It's proving to be difficult to find one around here in junkyards, and they won't sell me one at an auto parts store without a serial number, which of course mine doesn't have, the sticker is worn off. They also want mileage, which I'm sure these computers didn't store. 

PM me. Trick will be how soon you want it. Looks like about $30 for regular mail to a random zip based on your location, would take maybe two weeks to get there, but I work ten-hour shifts so can't make it to the post office while its open until Friday. I might be able to get it to a courier before then but I don't know what's around locally, and it might be a bit of a drive (50 miles +) to the nearest large courier's location. I wouldn't really be looking for more than cost to ship, it's not doing me any good and I can't guarantee I didn't cook it hooking it up to my '91. I guess I could hook it back up to see if it starts. Once I find it of course... It's in a box somewhere but after three moves in the last year I'm at a bit of a loss as to where exactly that box is.

I couldn't find an ecu pin out diagram from '91 to look for differences, if someone happens to have one. 

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Hmm, that's more of a hassle than I'd want you to go through, not to mention I seem to remember you live in Canada. The money conversion would probably be a pain, too. I may try rockauto, like DirtyComanche mentioned. Thanks for the offer, gogmorgo. 

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It's not too much hassle if all I'm doing is dropping it in the mail. I just can't guarantee I can get it to you any sooner than two weeks shipped out on Friday. Priority mail would be $50 IIRC and "guarantees" six business days. If I can find it I can try to grab a serial number off it too if that'll help you out at all. I've got to go digging through that stuff today anyway, need to reorganize my garage cause I'm sick of not knowing where anything is. 

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21 hours ago, gogmorgo said:

It's not too much hassle if all I'm doing is dropping it in the mail. I just can't guarantee I can get it to you any sooner than two weeks shipped out on Friday. Priority mail would be $50 IIRC and "guarantees" six business days. If I can find it I can try to grab a serial number off it too if that'll help you out at all. I've got to go digging through that stuff today anyway, need to reorganize my garage cause I'm sick of not knowing where anything is. 

Well I do appreciate it, I'll get back to you if I need it. I was lucky and found one the other day, won't be able to install it for a few days though. 

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Remanned computer, another new alternator and new battery. Relays and fuses checked again, ground and wires tested. I crank her over annndddddd.... 12.32 volts running. I don't know what to do. The field circuitry is getting the proper ohmage, too. 

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1 hour ago, PFCLeist said:

Remanned computer, another new alternator and new battery. Relays and fuses checked again, ground and wires tested. I crank her over annndddddd.... 12.32 volts running. I don't know what to do. The field circuitry is getting the proper ohmage, too. 

 

This hasn't happened to me, but I've read that a defective ASD (auto shut-down) relay can negatively affect the charging system. Just for grins, swap it out with one of the adjacent relays in the PDC. They are all the same relay in that row. 

1991PDC.jpg.ce16ad6babd8c3ee76354412403a73c8.jpg

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Would an auto shut down cause an intermittent starting issue too? Sometimes at random I turn the key and it won't turn over, but will max the gauges out. And other times it turns over and starts fine, seems like it could be a sticking relay or something. 

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1 hour ago, Ωhm said:

During engine crank only the ignition switch will ground certain bulbs, gauges or both. This function is called "bulb check". Could be normal for what you are seeing happen to your gauges.

I know it's normal, my point was more about the ignition switch doing what it's supposed to do, but an intermittent no crank. Perhaps whats causing this issue could be related to the alternator not charging. Also, swapping that relay with 2 others did nothing, unfortunately. 

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3 hours ago, PFCLeist said:

Would an auto shut down cause an intermittent starting issue too? Sometimes at random I turn the key and it won't turn over, but will max the gauges out. And other times it turns over and starts fine, seems like it could be a sticking relay or something. 

 

Possibly. Try swapping it out with another one from the PDC.

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