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What Is This Part On 96 XJ Alternator?

DirtySouthXJ

NAXJA Forum User
Location
Florida
Hi,

What is this part (black component in linked pic) attached to the back of the alternator?

** Link is directly to a jpeg, not a thread. I can't post my own pics here and this is the only pic of the component in question I could find **
https://www.jeepforum.com/attachments/dsc_0967-jpg.191240/

Should this be present on my 96 XJ? Someone has monkeyed around under the hood previously (add on wiring, un connected connectors etc.) and the engine has been replaced so I'm not sure what is supposed to be there and what is not.

I'm having charging issues that I'm trying to work out. My voltage/charging idiot light comes on when running. I get 11.95 V at idle when checked across the battery and from the alternator to ground. Also the battery drains when parked and not in use for some time.

Thank you.
 
I can't tell you what that black box is, but I can tell you that it belongs there. It is present on my '96.

I would suggest that you check your grounds thoroughly, especially if the engine has been replaced. Pay special attention to the grounds by the dipstick. There are multiple wires which go to that stud.

Have you had the alternator tested?

What is the condition of your battery terminals? In what condition are those wires at the other end?
 
I can't tell you what that black box is, but I can tell you that it belongs there. It is present on my '96.

I would suggest that you check your grounds thoroughly, especially if the engine has been replaced. Pay special attention to the grounds by the dipstick. There are multiple wires which go to that stud.

Have you had the alternator tested?

What is the condition of your battery terminals? In what condition are those wires at the other end?


Thank you Anak, that is good to know that it belongs there because I'm not sure what all is supposed to be or not. Supposedly the engine is out of a 2000/2001 and I'm not sure whether that means just the short block or if other parts were swapped over too. I do know that the intake is the older style, not a 2000/2001 style.

I did check and clean the grounds I could find which were:

- Upper firewall at center line, braided ground strap to the top of head (?), just aft of the fuel rail. This braided strap was oil soaked. This appears to be a standard engine to body ground and is the only one I've seen so far.

- Two ground wires with ring terminals to two studs (side by side) on the passenger side of the block, just aft of the A/C compressor. I cleaned the ring terminals and studs but there is some exposed copper strands that appear to have corrosion. I'm not sure how far back or how bad the corrosion is underneath the jacketing. Also not sure what these grounds are for.

- One ground wire with ring terminals on both ends from battery negative post clamp to passenger fender. I cleaned both ring terminals. The wire is semi heavy gauge (lighter than the main battery cables though). The wire and the ring terminal at the battery post clamp is not in great shape and very likely should be replaced.

- One ground at the black box in question on the back of the alternator. Whatever it is, it apoears to ground to the alternators case with a ring terminal.

^ These are the only grounds that I am aware of at this time. I did not see a ground point (stud) with more than one wire connected to it but I haven't had much time to work on it.

I have not had the alternator tested and likely won't be able to anytime soon unfortunately. I do have a replacement alternator on hand though.

I will say that the battery post clamps are not stock. Somebody did a hack job installing them too. There is a ton of exposed copper and it looks like they tried to strip the cables with a butter knife lol.

The thing is, I can see where bad grounding and/or connections etc. could cause low voltage, but there is also the parasitic drain aspect as well which leads me to believe that the alternator is bad (bad diodes).

I'm hoping it is the alternator and not some extra crazy electrical gremlin crap.
 
Alright, so I was able to do some more looking around this morning and I see the ground point near the dip stick Anak mentioned. I haven' t got a close look yet but I can see that the connection is soaked in dirty oil at a minimum. Also, there is a black with red or orange striped wire grounded there that has been cut and a crappy crimp connector installed. Does anyone know what this black with red (or orange) striped wire is for?

This ground point near the dipstick can be added to my previous list as the only ground to body/engine points I've found so far under the hood. I did trace the alternator's power wire to the underhood fuse/distrobution block near the passenger side fender and that connection doesn't look terrible, but it certainly can be cleaned and I'm going to do so today.

Unfortunately I don't have any on hand at this time, but there is a conductive grease called NO-OX-ID A-SPECIAL that I will order and use to protect all of these connections to prevent corrosion going forward. This grease is intended to protect electrical connections in harsh environments and is well regarded.

I will take some more meter readings after cleaning up these other connections and before trying the new alternator.
 
Oil soaked sounds like your situation is pretty similar to what mine was. Here is what I ended up doing at the dipstick ground: https://www.naxja.org/forum/showthread.php?t=1148570

Here is thread on upgrading the wiring for the alternator. Post #17 shows what I have done about the fusible link: https://www.naxja.org/forum/showthread.php?t=1142147&page=2

I can never seem to find the thread showing how I have done the battery terminals and related wiring on my XJ, but here is the Varmints' ZJ with the most important details: https://www.naxja.org/forum/showthread.php?t=1159228

As to the conductive grease, odds are you can find it locally at your Home Depot/Lowe's/Other Big Box Construction Supply. Ask for the grease used to deal with aluminum wiring. (Electrical supply house would be another place to look) It will probably be a conductive grease, perfect for use on your grounds. Check into the details of the specific product just to be sure. (For all I know there may be something out there that would be a poor choice.) That may save you the shipping and the time waiting.

Hopefully some of that will be useful for you.
 
Oil soaked sounds like your situation is pretty similar to what mine was. Here is what I ended up doing at the dipstick ground: https://www.naxja.org/forum/showthread.php?t=1148570

Here is thread on upgrading the wiring for the alternator. Post #17 shows what I have done about the fusible link: https://www.naxja.org/forum/showthread.php?t=1142147&page=2

I can never seem to find the thread showing how I have done the battery terminals and related wiring on my XJ, but here is the Varmints' ZJ with the most important details: https://www.naxja.org/forum/showthread.php?t=1159228

As to the conductive grease, odds are you can find it locally at your Home Depot/Lowe's/Other Big Box Construction Supply. Ask for the grease used to deal with aluminum wiring. (Electrical supply house would be another place to look) It will probably be a conductive grease, perfect for use on your grounds. Check into the details of the specific product just to be sure. (For all I know there may be something out there that would be a poor choice.) That may save you the shipping and the time waiting.

Hopefully some of that will be useful for you.

You're the man, brother! I will check out those threads.

Upgraded wiring is definitely in the long term plan along with an upgraded (higher amp) alternator. I wasn't planning on doing it yet though, my XJ was intended to be a long term project/recreational vehicle but she has been pressed into emegency service due to issues with my daily driver.
 
That black box is the ASD relay terminal per the FSM.
 
That black box has the two wires for the alternator ignition and the PCM sense /controller, i.e. one wire is ignition from the ASD relay. The other wire provides the ground via the PCM. The PCM contains the regulator which toggles the ground on and off to keep the voltages within specs.

The red and black wires there were added by the previous owner and not a part of the OEM wiring instead of the small wires contained in the black box. I could only assume there was/is a problem either with the PCM (regulator) or the wires between the PDM, the PCM and the alternator.

There is a third wire in that black box. It is about an 8AWG wire with a ring terminal. It should be connector to one of the studs on the alternator. There is also a brass strap on the opposite end that is bolted to another of the studs on the back of the alternator.
 
That black box has the two wires for the alternator ignition and the PCM sense /controller, i.e. one wire is ignition from the ASD relay. The other wire provides the ground via the PCM. The PCM contains the regulator which toggles the ground on and off to keep the voltages within specs.

The red and black wires there were added by the previous owner and not a part of the OEM wiring instead of the small wires contained in the black box. I could only assume there was/is a problem either with the PCM (regulator) or the wires between the PDM, the PCM and the alternator.

There is a third wire in that black box. It is about an 8AWG wire with a ring terminal. It should be connector to one of the studs on the alternator. There is also a brass strap on the opposite end that is bolted to another of the studs on the back of the alternator.


Hi Techno,

That pic is not mine or of my XJ, it is the only pic I could find that shows the part in question (now known as the ASD relay evidently). On my XJ those two additional wires are not there that I can see. I do have the wire with ring terminal and it is grounded to the alternator case via a stud. I'm really hoping this is not a PCM issue. Why they would have the PCM control alternator charging is dang mystery, and sounds like an expensive one at that. My old Chevy's use one wire straight from the alternator to the battery, no computer crap to go wrong, either the alternator is good or it's not. So let me ask this, if it is not the alternator, but a bad PCM..

- Is there another year PCM that will eliminate this function from the PCM?

Or

- Is there a way to go to another style alternator, like a one wire Chevy alternator?
 
Hi Techno,

That pic is not mine or of my XJ, it is the only pic I could find that shows the part in question (now known as the ASD relay evidently). On my XJ those two additional wires are not there that I can see. I do have the wire with ring terminal and it is grounded to the alternator case via a stud. I'm really hoping this is not a PCM issue. Why they would have the PCM control alternator charging is dang mystery, and sounds like an expensive one at that. My old Chevy's use one wire straight from the alternator to the battery, no computer crap to go wrong, either the alternator is good or it's not. So let me ask this, if it is not the alternator, but a bad PCM..

- Is there another year PCM that will eliminate this function from the PCM?

Maybe the very early years when they were fitted with an AC Delco alternator. Someone with the early XJ will answer that question. However, sometime in 1995 or 1996 the PCM changed. They are not compatible. Matter of fact, even the HO and post HO PCM's are year specific.
Or

- Is there a way to go to another style alternator, like a one wire Chevy alternator?
 
Hi Techno,

That pic is not mine or of my XJ, it is the only pic I could find that shows the part in question (now known as the ASD relay evidently). On my XJ those two additional wires are not there that I can see. I do have the wire with ring terminal and it is grounded to the alternator case via a stud. I'm really hoping this is not a PCM issue. Why they would have the PCM control alternator charging is dang mystery, and sounds like an expensive one at that. My old Chevy's use one wire straight from the alternator to the battery, no computer crap to go wrong, either the alternator is good or it's not. So let me ask this, if it is not the alternator, but a bad PCM..

- Is there another year PCM that will eliminate this function from the PCM?

Or


Maybe the very early years when they were fitted with an AC Delco alternator. Someone with the early XJ will answer that question. However, sometime in 1995 or 1996 the PCM changed. They are not compatible. Matter of fact, even the HO and post HO PCM's are year specific.


-
 
Hi Techno,

That pic is not mine or of my XJ, it is the only pic I could find that shows the part in question (now known as the ASD relay evidently). On my XJ those two additional wires are not there that I can see. I do have the wire with ring terminal and it is grounded to the alternator case via a stud. I'm really hoping this is not a PCM issue. Why they would have the PCM control alternator charging is dang mystery, and sounds like an expensive one at that. My old Chevy's use one wire straight from the alternator to the battery, no computer crap to go wrong, either the alternator is good or it's not. So let me ask this, if it is not the alternator, but a bad PCM..

- Is there another year PCM that will eliminate this function from the PCM?

Or


Maybe the very early years when they were fitted with an AC Delco alternator. Someone with the early XJ will answer that question. However, sometime in 1995 or 1996 the PCM changed. They are not compatible. Matter of fact, even the HO and post HO PCM's are year specific.


-

Thank you Techno! From a consumer point of view it is a terrible idea to integrate something like voltage regulation into the PCM. Sure, when brand new PCMs were readily availible over the dealership parts counter, this was probably great for Jeep's pockets, but damnit man this a nightmare 27 years later with little to no new parts support. I may just put together a carbed setup to keep on stash, because once these year specific PCM's kick the bucket and start getting super hard to impossible to find in working condition, how are you going to keep the vehicle running? Or even charging lol. Year specific PCM's (and evidently fuel pumps too lol) make no sense imo. Besides being bad news for us, it didn't make any sense when these vehicles were new, I mean think of how many different versions of functionally the same parts for the same vehicle model they would have had to stock and store to be able to service these vehicles while still under warranty and/or supported? At least three different fuel pumps to cover 1995-1997? That's outrageous and incredibly inefficient.




You can do a stand alone voltage regulator. There are kits. Here is one example: https://alternatorparts.com/external-voltage-regulator-high-output-alternator-kit.html

Thank Anak! Interesting, and very helpful too. Reading their page they mention that upgraded alternators (higher amp) have been known to fry the in PCM voltage regulator, I'm very glad to know that since an upgraded (higher amp) alternator has always been in the long term plan.
 
So doing some more looking under the hood, I see that there is a wire like fusible link at the same location (between the two large wires) that Anak has a 100 amp fuse in his first post in this thread
https://www.naxja.org/forum/showthread.php?t=1142147&page=2

I would assume that if the fusible link was bad, that I would be getting no power at all instead of seeing 11.95v from alternator output to ground and between the positive and negative posts? Also, I can't see how this fusible link would be causing a parasitic drain on the battery. I'm thinking it has to be bad diodes in the alternator or bad voltage regulator. I hopefully will be able to het the alternator bench tested soon and that should hopefully tell me if it is the alternator or the voltage regulator. I will likely pick up that PCM voltage regulator bypass that Anak linked in either case, because I really don't like the idea of that being integrated into the PCM and I plan on going to around 240 amp alternator in the future.
 
I dont see where you checked for a bad battery or for an unusual battery drains before just throwing money at it?
 
You can do a stand alone voltage regulator. There are kits. Here is one example: https://alternatorparts.com/external-voltage-regulator-high-output-alternator-kit.html

I have one of those regulators here in my parts bin that was installed for a few weeks then removed. I liked the idea as I could adjust the output to my preferred 14.5 volts at the battery. What I did not like was the way in which it cycled...one could actually see the lights going brighter then dimmer at idle speed at night. Some users are very happy with them, I not so much. I looked at the unit a few weeks ago and pondered over a decision whether to keep it with the stack of "It may be useful someday".

If the regulator is bad, the external regulator could be a viable option for you.

RCP Phx suggestion is a great on. Identify the problem before spending money.
 
I have one of those regulators here in my parts bin that was installed for a few weeks then removed. I liked the idea as I could adjust the output to my preferred 14.5 volts at the battery. What I did not like was the way in which it cycled...one could actually see the lights going brighter then dimmer at idle speed at night. Some users are very happy with them, I not so much. I looked at the unit a few weeks ago and pondered over a decision whether to keep it with the stack of "It may be useful someday".

If the regulator is bad, the external regulator could be a viable option for you.

RCP Phx suggestion is a great on. Identify the problem before spending money.


Interesting and good to know! Thank you. I'm not spending any money yet other than picking up an alternator to have incase the alternator is the issue, I do have the receipt and it is unopened, so if not then I'll just return it. I am very hesitant to use it because I do plan on going to a 240 amp alternator to run anything I feel like adding in the future regardless if any of these issues were present or not, that has been the plan since before I knew there was a charging/draining issue. Evidently, it is recommended to go to a stand alone voltage regulator or better yet an internally regulated alternator and bypass the PCM regulation all together which makes sense to me and is something I very likely will do regardless of this charging/draining issue, because I don't want PCM related charging issues going forward (hell, I don't even want a PCM to be honest) and if it's not the issue now, it is only a matter of time before 25+ yr old fragile electronics kick the bucket. Integrating charging control into the PCM is a terrible idea in all cases other than for the manufacturer to sell you a very expensive PCM over a simple charging/draining issue(n) In my experience with other make vehicles, the voltage regulation was integral to the alternator and the alternator only had one wire that connected directly to the battery. No PCM integration (hell, no PCM at all lol!), no extra wires or relays, no wild goose chases..either the alternator was good or it wasn't period. If it wasn't for this PCM voltage regulator, there wouldn't even be a question, either there would be proper voltage at the alternator, or the alternator is bad.

Everything else I have done has been free, like testing for voltage with a multimeter I already had and cleaning grounds with a wire brush I already had. The low voltage combined with parasitic draw could be due to bad alternator diodes and/or a bad PCM voltage regulator, evidently either can cause both symptoms at the same time. Sure, another component being shorted out could cause a drain, but what other than an alternator diode and/or bad voltage regulator would also cause low charging voltage along with it? I will bring the alternator in to get bench tested but I can't at this time. I did clean all but one ground which I can't get loose without buying another socket, it is the braided ground strap from the firewall to the head/block right behind the fuel rail. I did also clean the contacts at the fusible link at the underhood fuse box. Everything else I could think of has been cleaned and well tightened. Today I read 12.05 v at both the alternator to ground and across battery terminals at idle, which is only slightly better than the 11.95 v I was reading before.
 
By the way, I usually test my alternator on the engine using the test method indicated in the 1996 workshop manual as indicated in group tab 8C page 5. This is easily done by jumper the negative (not the positive) wire on the back of the alternator to a clean ground. Care must be taken to monitor the charging voltage with a test meter. This is very important. Why? With a good alternator, voltages could quickly exceed 15 volts and keep going up.
 
By the way, I usually test my alternator on the engine using the test method indicated in the 1996 workshop manual as indicated in group tab 8C page 5. This is easily done by jumper the negative (not the positive) wire on the back of the alternator to a clean ground. Care must be taken to monitor the charging voltage with a test meter. This is very important. Why? With a good alternator, voltages could quickly exceed 15 volts and keep going up.

Thank you Techno! I'll see if I can figure that out and give it a try.

I did a little bit more looking around under the hood today and now I'm not sure if the PDC is correct for this year. Supposedly, the engine is out of a 2000 or 2001 XJ but I can say for sure it does not have the newer style intake, so maybe just the short block?? I looked in the 96 owners manual and they show a diagram of the 96 PDC, it also lists two positions for 60 amp "generator" maxi fuses. When I look at the underhood PDC, I only see one 60 amp maxi fuse and the layout doesn't match the diagram in the owners manual. The PDC cover also has a diagram that does match the PDC but doesn't match the owners manual diagram. Also the external "fusible" link section has two square head bolts with a wire style fusible link between them, but I seem to recall seeing other 96's where those wires were on one single square head bolt with nothing between them. I have no idea if any of this is correct or what the PO has done! I do see alot of wire routing "tabs" not connected to anything allowing the wires to just flap around.
 
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