Alternator Not Alternating

[brokedownboys]

I thought I was hot s*** because I swapped my fuel pump and that was a bigger undertaking than usual for me.


Time to prime the fuel system, right? I put a jumper wire in the Fuel Pump Test Connector and turned the key to ON, but no gas. Dumbass time. I yanked out the Circuit Opening Relay and bypassed it with another jumper wire. Still no gas when I turn the key to ON. Instead I get visible sparks and a small cloud of spoke. Nice.


It turns out the battery was dead from sitting for a month and I seriously should not have messed with the Circuit Opening Relay at all. I swap my dead battery with a charged one from my girlfriends car and put a new fuse in the EFI slot (it was visibly blown). I put the Circuit Opening Relay back in its spot, put the jumper wire in the Fuel Pump Test Connector, turn the key to ON and the fuel pump starts whirring. Van fires up and I take it for a premature celebratory test drive.


It feels good to be back on the road (the fuel pump job took me a awhile). But after about a mile I notice my lights are getting dim. This is when I should have turned around, but instead, I embark further on my fateful test drive.


After two miles I can hardly see the road and the engine starts to bog down. I barely make it off the highway when the thing dies on me.


I run home (2.5 miles in the dark). For some reason (I look like a tweaker) no one stops to give me a ride. Me and my girlfriend return to the scene with jumper cables. The car starts up but immediately dies when I disconnect the jumper cables.


My girlfriend has a smart idea that we take the battery home and charge it using a trickle charger. After a few hours of charging we drive back to the van and plop in the fresh battery. It has just enough charge for us to limp it home (with no headlights on).


I assumed I had an Alternator issue, which is strange considering I never had problem before doing the fuel pump. I ordered an AC Delco alternator off RockAuto and installed it per llammavan's very helpful guide. Unfortunately this did not abate the problem and the van still dies shortly after I disconnect the jumper cables. The voltage across the battery terminals does not increase while the van is running either.


Now my suspicions are directed towards the Alternator Wiring Harness. Frankly, it does not look stock, as there is a lot of electrical tape involved in that situation. How can I test the continuity of my Alternator Wiring Harness? Is there some fuse I am not considering which could prevent my alternator from the charging the battery? Could my Fusible Link be at fault?


I would simply replace the Alternator Wiring Harness, but I understand that part is NLA. Do I need to learn some electrical engineering and make a new one from scratch? What should I do??


HELP A YOUNG VAN WAGON OWNER,
Jackson

[Jan-Willem]

I only have experience with one van, mine, a 86LE
but mine has/had that 3-wire alternator control cable, and mine could simply unplug on both ends, it is maybe 2 feet? On my van I found 17 repairs on that wire… I made a new one, but i kind of had to do that anyway, to fit an alternator that I could buy locally. But unless mine was really a mishap, maybe that wire is just a weak point, it is very near the manifold. If yours is the same, you can unplug it, test resistance with a multimeter. If good, clean the contacts and put it back, or fix it

[AD2101]

Are you getting Christmas lights on the dash? I'd backtrack to see if you done goofed anything up when you were messing around in there (unlikely but since you noted the issue started after the seemingly unrelated repair it doesn't hurt to check). I'd then check the fusible link (https://www.toyotavantech.com/forum/showthread.php?136-The-fusible-link-thread) and, if that checks out fine, examine the alternator harness. If it's the harness, you can make a new one using this guy (https://www.amazon.com/XtremeAmazing-Alternator-Harness-Repair-Connector/dp/B06XCJSF51), and this guy (https://www.repairconnector.com/products/Nippondenso-Toyota-MR2-Alternator-Connector-Round-3-Wire-Male-Terminals.html) (potentially relevant thread (https://www.toyotavantech.com/forum/showthread.php?4755-Christmas-dash-after-installing-new-alternator)). When I had to rig up my own harness 6 years ago I just spliced the alternator end of the plug into the existing harness on the van since it was still good but it's straightforward enough to make a whole new one if you need since they are NLA from Toyota now.

Another potentially relevant thread. (https://www.toyotavantech.com/forum/showthread.php?2521-Alternator-No-Charge-No-Christmas-Warning-lights)

Good luck!

[brokedownboys]

Good evening van wagon lovers,
Little update to my situation here. The -/+ light is no longer illuminated when the key is turned ON. I have already replaced the 7.5 Amp CHARGE fuse. Does this mean I am no longer under a Christmas Dash condition?
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Since I already replaced the alternator and still no charge, I am going to troubleshoot the harness. Wires S, L and I fell out of their protective plug during installation of the new alternator, so they were suspect #1. No contact, no electric field, no charge, right?

In order to identify the wires (as illustrated in AD's potentially relevant thread) I set up the following test:
-Unhook battery
-Unplug 7.5 amp CHARGE fuse
-Key Off
-Set multimeter to 20V DC
-Ground negative terminal of multimeter to chassis

In this condition, all three wires read 0 volts.

Then I hooked up the batter and a single wire read 12 volts. I marked this wire S (sense).
I turned the key to ON and another wire also started reading 12 volts. I marked this wire I (ignition).
I plugged in the 7.5 amp CHARGE fuse and all three wires were hot. I marked the last wire L (lamp).
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Since I am getting voltage at all three spade connectors, the next item I scrutinized was this guy.

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Indeed he's looking a little smashed up, maybe enough to prevent the spade connectors from making contact with the alternator? Gonna solder on a new plug and see what happens. Is my thinking sound?
-J

[Jan-Willem]

https://www.toyotavantech.com/forum/showthread.php?2521-Alternator-No-Charge-No-Christmas-Warning-lights
Looks like someone already ‘touched’ those wires, they originally are white (sensing), yellow (lamp) and black-yellow (ign)

[brokedownboys]

Another disappointing night...

Many layers of brittle plastic tape gave way to what remained of the factory wiring harness. The color coding of the factory wiring harness confirms my previous determination of wires L,S and I. That at least is reassuring. But as you can see by that little yellow thing, the previous wing-nut made use of the same while constructing the harness I have inherited from him today.

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I called over a friend, we took the undamaged end of the factory harness, soldered on some 16 gage wire, and crimped on a few spade connectors in lieu of the damaged pigtail. Then I plugged the spade connectors into the internal voltage regulator's little nubs one by one.

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We swapped the battery from my gf car which reads 12.4 volts. The van starts just fine.

But to my disgust, the voltage at the battery terminals does not surge to 14, it just slowly declines. Even more upsetting, we are only reading 1 volt at the [+] box.

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I am open to any possible explanations as to what is happening. I do not believe I crossed wires L, S, or I, but will check again. I can see the pulley turning, how can I confirm I have electric field in there?

I understand that circuit S connects to the positive terminal of the battery via fusible link 0.5 to sense the voltage of the battery. What about circuits L (lamp) and I (ignition)? How does the L circuit connect to the +/- lamp and the 7.5 CHARGE fuse? How many volts should wire L be reading when things are working normally? How does the I circuit connect to the rest of the ignition circuit? Circling back to my first post, are either circuits intermingled with the EFI system? My friend thinks I might have fried my ECU when I jumped the fuel pump, anyone able to talk me down from that ledge rn? THANKS

[Jan-Willem]

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12422
Hi
i hope you can read the charts.
J3 is your plus box, it should always be battery-level voltage. Running or not running. One side is connected to your battery through 2 fusible links, the other side runs directly to the main pole of the battery.
if, when not running, it measured no voltage to the ground of the battery, one of these fuses must be malfunctioning. If it does, but not to ground of the engine, the ground wire to your engine must be malfunctioning, which would be weird if it does start.

[brokedownboys]

Jan,
Thank you so much, this is the information I need.

I see fusible link 0.5 (circled in blue) which protects the white S (sense) wire going into the alternator. I see the two fusible links (circled in orange) which protect the B (alternator output) wire.

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I agree with your theory that fusible links on the B circuit could be malfunctioning. Unfortunately, I am unable to read your picture since it is such low resolution. Are you able to identify the two fusible links I circled in orange? Then I can browse the fusible link thread, locate the linkages on my van and replace them.

Thank you!

[Jan-Willem]

Yeah sorry, i do not know how to fix the resolution, it is fine on my ipad, but scales down when i post.
the bottom one is labeled fl2.0L the upper one is fl1.25B
https://www.toyotavantech.com/forum/showthread.php?136-The-fusible-link-thread
i can’t help you with hands on experience here, as both these fusible links, on my van were butchered beyond recognition. I replaced whatever was left with a twin box for maxi-fuses.

[brokedownboys]

Behold fusible link 1.25B. Not exactly confidence-inspiring, but at least it appears to have done its job. Could my botched jumping of the fuel pump been the straw that broke this camels back?

12435

I upgraded to klein crimpers and made a new one out of generic 20 gauge fusible link from NAPA. Any objections?

12436

It appears to have done something since I have 12 volts at the [+] box now, which is technically progress. Otherwise I remain in the same sad boat. Van starts up and produces no additional volts. Alternator still not alternating.

I even went to the trouble of un-plucking each pin of my hand-made harness and confirming there is 12 volts at all three connectors. As far as I can tell, the alternator is getting positive voltage where needed. Is it possibly not grounding? Are there any other fuses I need to check?

[brokedownboys]

My problem was fusible link 1.25B all along. It assume it melted when I short-circuited the vehicle in post 1. On the bright and shiny side, my J3 aka [+] box now has 12v with protection :-D Plus, now I can now strut my vans cute new blue piercing all around town <3 So its not all is bad in brokedowntown.

DO NOT buy a faulty AC DELCO alternator on RockAuto.com. As I am only set to receive a 1/3 refund of the shipping cost associated with this unit, I am compelled to lodge a 1/3 experience here on the toyotavantech.com public forum, an experience which, sadly, actually, could have easily been a 3/3 rock auto experience.

The irony of it all is I had in fact read timsrv's thorough admonishment on this precise subject and was resolved to buy a DENSO unit. Unfortunately the similarity of names and fog of war prevented me from heeding a wise man's prudent warning.

I have not only gained priceless knowledge of my charging system, but fortune has befallen me an original copy of the Toyota Van 1987 Wiring Diagram Thank you dad for the critical Christmas present and thank you Jan-Willen for sharing your copy. I am happy to do the same with others who share the enthusiasm for Van Wagon.

Anyway, van reveal:

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