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Ok, here is what I am dealing with.

This is the alt on the 88 2.6.
88 alt.JPG

As you can see, it has a round connector.

This is the alt I took off of the 91 2.8
91 alt.JPG

It has a square connector. (Well, rectangle, technically.)

Does anyone know the pinout on these ?

I cut the square connector off of the 91. It only has one wire going to it.
onewire.JPG


I'm certain this is going to be a fairly simple adaptation to make.

Just can't seem to access all my brain cells at the moment.
 

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Is that (2.8L) the gm alternator?
 

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I don't think it's gonna work ...... Just the wrong one..
If the alt's do run the fuel pump and stuff you would have to yet figure out another relay, that is if would even mount.
 

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Discussion Starter · #4 ·
shooter said:
Is that (2.8L) the gm alternator?
You got me.

The motor is gm, so I would assume the alt is as well.

This has all just become too much frustration. I have spent way too much money on this truck, and only gotten to drive it to town, 4 times. I'm ready to just give up on it.

Rather than that, I am just walking away from it for the night.

I may try to find the info I need, online, but I am not going back out there again, tonight.
 

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Discussion Starter · #5 ·
bradzuzu said:
I don't think it's gonna work ...... Just the wrong one..
If the alt's do run the fuel pump and stuff you would have to yet figure out another relay, that is if would even mount.
I'm not concerned about the fuel pump. Very easy bypass.

I'm just not sure what all the wires do. There are 4 for the isuzu alt I have to figure out, and the one for the gm alt.

Once I get that figured out, I'll find ways to bypass what needs bypassed.
 

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Discussion Starter · #6 ·
I wanted to drive it to town today.

It had been running for a while. Charged the battery back up enough that it would start again.

Let it sit for probably 35 minutes, to get ready to go to town... And once again it won't start, because the battery is too low. I had to drive the jimmy into town.

I'm glad I didn't drop the insurance on the jimmy, or 'swap' the coverage over to the trooper. But damn ! I'm paying insurance on both vehicles now. And getting nothing to show for that extra expense, with the trooper.

I just can't afford to buy another alternator right now.

And while it WAS running today, I heard the water pump bearings. Now I'm going to have to replace that !

I've already spent over 1500.00 on this truck, and only gotten to drive it 4 times. I'm sick of it !

I could have bought a nice already running vehicle for that amount.
 

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Hopefully, the gm alternator is the cs130 series. If so, the pages in this link might be helpful. http://www.alternatorparts.com/cs130_sbpage1.htm

Additionally, I have a decent schematic of the 2.6L alternator from the electrical troubleshooting manual if you need me to scan and upload.
 

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Discussion Starter · #9 ·
bradzuzu said:
Your battery is new??? This time of year battery's start to die after cooking in the summer heat..
Not brand new. But not more than a year old. And it's an optima red top.

shooter said:
Hopefully, the gm alternator is the cs130 series. If so, the pages in this link might be helpful. http://www.alternatorparts.com/cs130_sbpage1.htm

Additionally, I have a decent schematic of the 2.6L alternator from the electrical troubleshooting manual if you need me to scan and upload.
Jackpot !!

Wow ! Shooter, I'd kiss you if you weren't so damn ugly !

Yes, I do believe it is the cs 130 series. (I guess it could be the cs121. I'll find out tomorrow.)

And hey, looka that ! It sez that the cs130 puts out 85 to 105 amps. That's better than the old one.

Very helpful article. Thank you.

Man, I'd love to have the entire electrical troubleshooting manual.

I'll gladly accept your offer of a scan of the schematic !

Thank you again.

:D :D :D
 

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Here you go. They're in no particular order. I uploaded those I thought you might have interest in. Not sure, however, the pic showing fuse #14 and the one showing the fuel pump appear to me to show the circuit from the alternator to the fuel pump via the key switch. I made them links due to the size I chose.











 

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Discussion Starter · #11 ·
shooter said:
Here you go. They're in no particular order. I uploaded those I thought you might have interest in. Not sure, however, the pic showing fuse #14 and the one showing the fuel pump appear to me to show the circuit from the alternator to the fuel pump via the key switch. I made them links due to the size I chose.
Fantastic !

Thank you very much !

Every one of those is going to be helpful. Even just the first one, leads me back to the alt being the biggest gremlin in this problem I've been chasing.


Look at the fusible links. Pulling the 1 black, and .4 green, both worked to get rid of the mysterious drain. And both lead straight to the alternator.

I wrote more about the alt problem last night, in the blathering thread. I'll repeat a bit of it here...

On monday, I couldn't start the trooper. The battery was completely dead. (And so started the search for the mysterious drain.)
I took the fully charged battery out of the jimmy, and put it in the trooper.
I drove to a friend's house, then back home. Then started toward town. A total of maybe two miles.
The troop started stumbling then died completely. I was able to get it started again, and started back home. It died again. I started it again, and barely limped it home.
Took that battery back out and put it back in the jimmy. Barely got the jimmy started. It was obvious that the battery was drained a lot.
Drove to town in the jimmy, and during the trip, that battery got fully charged once again.
After all the futzing around yesterday, the trooper once again would not start, and I had to drive the jimmy again. The battery in the jimmy, was still fully charged. So, nothing wrong with the battery.

I think the bottom line is that the alt here, just barely does it's job. But I think it is draining the battery, while the troop is turned off. Plus, I think that when it is running, it is putting out volts enough to keep the troop barely running. (Fuel pump works.) But no, or almost no amps. Therefore it isn't really charging the battery. As evidenced by the fact that the troop drained the other battery in just two miles of daylight running.

Now I am going to get busy with the wiring daigrams and the alternator info that you have given me, to work out a way to work around the installation issue...
 

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So it sounds like either a bad voltage regulator or that "diode" which is used to prevent the battery from discharging back to the alternator. As you probably know, you never (if possible) want the alternator to charge a very low battery due to it will soon fry the alternator. Regarding electric fuel pumps (in tank), they are designed to operate on millivolts (they initially receive 12v) to minimize explosion. Glad to see the schematics might prove helpful.
 

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Discussion Starter · #13 ·
shooter said:
So it sounds like either a bad voltage regulator or that "diode" which is used to prevent the battery from discharging back to the alternator. As you probably know, you never (if possible) want the alternator to charge a very low battery due to it will soon fry the alternator. Regarding electric fuel pumps (in tank), they are designed to operate on millivolts (they initially receive 12v) to minimize explosion. Glad to see the schematics might prove helpful.
I did one more test this morning.

NONE of my own circuits are causing a drain.

So, everything else disconnected... I mean everything. ECU, Radio, everything.

With the round plug removed from the alt, but the fusible links connected, (That square black connector at the battery positive terminal.)... Weeee tiny draw. (That is the gremlin I was chasing yesterday.)

With the round plug removed from the alt, and the fusible links disconnected... Zero draw.

With the round plug plugged in, and the fusible links connected... Draws everything the battery has.

With the round plug plugged in, but the fusible links disconnected... Zero draw.

Conclusion:

Unless I am mistaken,

The alt is not charging the battery up, while the truck is running. (While running, the battery drains.)

And the alt by itself, is drawing the battery down, while the truck is not running.

Yesterday, I walked away frustrated. Left everything connected to the battery.

Luckily, I had unplugged the round connector on the alt, and hadn't plugged it back in.

This morning... The battery tests out at exactly the same level it was, when I closed the hood yesterday evening.

Again, further proof that it is the alternator that is at fault.

~~~~~~~

Thanks again, for the data.

~~~~~~~

In my testing I have noticed that when the truck is turned off... The ecu draws more from the battery, than the radio does.

Pretty good radio, I guess.

~~~~~~~

Next up is taking the old alt out, to see if the new one can be put in it's place.

If not. I have already discovered that I can mount the new one, where the smog pump was. (Just need a piece of pipe as a spacer.) Bonus to this is it gets the alt up toward the top of the engine.

I just don't know if the belt will work with the alt put up there.

One trick I have up my sleeve... If the new alt will not fit in the old position, and the belt won't work in the new one... I still have the belt tensioner that I took off when I removed the AC. I may be able to work something with that, to get a belt to work, with the alt in the higher position.
 

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Discussion Starter · #14 ·
Just a side note.

When I have finally worked this out, I will merge the posts from this thread into my 'blathering' thread.

I will probably post a new thread with a 'clean' writeup of the mod.
 

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Well, it's time to get creative.

I can't mount the new alt in either location, top or bottom. At the top, it is pinched between the exhaust manifold and the MAF. At the bottom, it is the wrong bracket.

I am still going to try to do this using the resources I have.

I can't afford another alternator.

My plan: Take both alts to town, tomorrow and have them tested. Knowing full well that the tests they run will not tell me whether the fuel pump circuit is working or not. They should still be able to tell me whether it is going to be a waste of time with the new one. Or whether the old one has a bad diode or something.

My hope is that the new one will be ok. Not holding much hope for the old one.

Next, I am going to cut the bracket that was used for the smog pump.

Then bolt it in place of the bracket at the bottom, that was for the old alt.

From there it will still take some adapting, but it should be workable.

Pics:
supposed to be.JPG

This is the current bracket. (Unbolted and just sitting there.)

engine side.jpg

This is the two brackets. You are looking at the engine side. The side that is flat against the engine, when they are bolted on.

The top one is the old smog pump bracket. The bottom is the alt bracket.

The red circles on each bracket are identical. You can see that I am going to have to cut or drill on the smog pump bracket, to be able to bolt it in place of the old alt bracket. The arrow, of course points to the one that will have to be cut or drilled.

bracket.jpg

Now this is the bracket from the face side. The bracket comes in two pieces. You bolt the first one to the engine, then bolt the second piece to the first. Second piece being on the left.

The red circles are there to show where the holes will have to be. The green lines are what I will probably end up doing. That end of the bracket has to be cut off a bit because one of the motor mount bolts is in the way. So I may cut it off, then just cut a groove back to where the second bolt will have to go.

And last:
location.jpg

The first half of the smog pump bracket kind of just sitting there close to where it will be bolted.

I'm taking the alts in to be tested, first. Because it doesn't make sense to go any further without doing so.

Then I'll have to get the first half of the bracket bolted on, and get the second half bolted to it... To see if I am going to have to move that bracket. I'll do it without cutting, by stacking washers under it on the one bolt I will be able to use. If the bracket has to be moved to one side or the other, from there, I will not have cut it prematurely.

Hopefully I'll have some sort of bracketry worked out by tomorrow night, and will be ready to move on, to the wiring.
 

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Discussion Starter · #16 ·
Went to town today.

Had the alternators both tested.

Only question that remains how, is whether to have Tad change my forum name to "Dumbass" or "complete idiot".

Both alts tested out perfect. (I neither know, nor care whether the 'fuel pump circuit' was tested.)

I described the problems, and got them to re-test. 5 different ways, they tested it. TRYING to make it fail. It passed everything with flying colors.

So, back to the drawing board.

It does make things a bit simpler. Now I don't have to figure out how to make some bracketry.

Sooo... Last thing I remember about this is that the battery was drained overnight. In my testing I found that if the round plug is plugged into the alt, with the vehicle off, it drains the battery overnight. (Round plug plugged in, and fusible links all plugged in.)

But with the round plug unplugged... No drainage.

It was natural to assume it was a fault in the alternator.

Now of course, I have to look for the fault elsewhere.

Maybe a wire in the harness is grounding to the frame or something, when the connector is plugged in. But doesn't make contact with the frame or whatever, when I unplug the round connector and lay it aside.

Or maybe it's something else.

The recent changes included my lock circuit, my blower circuit, and my power window circuit. I have tested those circuits and found no faults. I have even completely removed those circuits, and had no effect. No change whatsoever in the problems.

And one other thing. When I had the dash apart, I found that several of the lights were missing, in the center of the dash. One of them being the idiot light for the battery/alt.

I replaced all of the missing lights and the round plug thingys that the lights go into. Now all those lights in the center light up when they are supposed to.

I am wondering if there is a problem there. And that is why they had those bulbs and their carriers out of there ?

Well, whatever. I have to get back to tracking circuits and figuring out what is actually wrong. The battery didn't drain itself. I have now had that battery in the jimmy for a week, and a couple trips to town, with absolutely no problem.
 

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Quick and dirty test. This will give you a good starting point.
1. Disconnect neg cable from battery and use test lamp / meter between neg post and neg cable.
2. One by one, remove fuses until light/meter shows nothing.

Are you sure they tested the diode pack which keeps the battery from feeding back to the alternator?

Have you checked the wires at the terminals on the round connector?
 

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Discussion Starter · #18 ·
shooter said:
Quick and dirty test. This will give you a good starting point.
1. Disconnect neg cable from battery and use test lamp / meter between neg post and neg cable.
2. One by one, remove fuses until light/meter shows nothing.
I'll do exactly that, the next time I go out there. Maybe later tonight, maybe wait until tomorrow. Kind of needing a break, right now.
shooter said:
Have you checked the wires at the terminals on the round connector?
I'll do that, as well. Also going to check all the wires that go into the connector, for grounding out somewhere.

I am going to leave the alt out right at first, for ease of testing for ground faults.
shooter said:
Are you sure they tested the diode pack which keeps the battery from feeding back to the alternator?
I told them what was happening, and they immediately tested for that.

I was standing right there. At my insistance, they really tried to make it fail. They threw everything they had at it, and it still passed.

If they thought they were going to sell another alternator, I'd think they would really want to have had this thing fail. LOL

Good news, the other one IS a CS130. :D :D :D Kind of thinking about going ahead and making the swap, sometime later, just because of that. LOL I just want to get the troop back on the road for now.

The original alt is only 50 amps. Even an old chevy IS type, is at least 60 amps and has a bigger body, and better cooling...

Besides the amperage, price is another incentive. The bosch is almost twice the price of the CS130.
 

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Yep, the 130 sounds like a no brainer. Believe the 88 and up with a/c had a mighty 60 amp and no a/c had 50 amp.
 
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