Wiring GM alternator to Toyota harness...

[91 4runner]

Yes if the light bulb is out then you don't have a + signal to the field and the alternator won't charge

 

[xxfullsailxx]

so the bulb is good...but there is a "charge light relay"

...that's where i'm going next i presume?

 

[xxfullsailxx]

COULD THIS be the culprit?

well, found the charge light relay...

looking at the insides, everything looks in tact...
wondering if anyone knows how to test it?
(edit: see below)

or, do i just need to call toyota parts dept. for a new one?














edit: duh...how to test the charge light relay is in the FSM dummy...

 

[xxfullsailxx]

well the charge light relay seems to be showing continuity in places it shouldn't.
AND it turns out, that FSM is pretty darn handy...

thank goodness for my landcruiser to enable me to learn so much!

charge lamp relay is pretty common on mid-80's to early 90's toyota's...and seems to fail every-so-often according to findings on google.

Toyota OEM part #27790-13010 (I am calling Toyota tomorrow to see about price & availability)
Borg-Warner #R4775 (seems to be still in production-Advanced Auto Parts: $68.99 2-days out)
Carquest #56-2138 (unavailable)

found a used one on ebay for ~$30 free shipping...ordered it for back-up.

hopefully this is my primary problem at this point (knocking on wood).

 

[ntsqd]

Was it me I'd look for the wire from the charge light at the charge relay's socket. Run a temporary jumper from that position to the I terminal on the alternator and then check for charge.

I'm kind of mystified by the relay. My experience with Delco CS and SI series alternators is that Ign switched 12VDC through a charge indicator light bulb is enough to make them happy. Why the OE alternator needs a full 12 volts is curious.

Also, in reading the MAD link it looks like looping the voltage sense wire back to the charge stud on the Delco alt. is less than ideal. It works, and I've done it, but I may just change that on my Mini. Sensing closer to the battery results in the regulator adjusting the charge voltage to be proper once past the voltage drop in the charge wire.

 

[Elbert]

I think most of the problems with engine swaps and the alternator have no relationship to the OEM toyota parts and wiring , but more often errors made with the swap. I don't recall what you said you were running for the engine harness.

I have a single wire CS140 custom alternator that is a single wire version, my engine came stock with the CS130...

Not sure what version of the GM Alt you have on your engine...as I belive you said you were running a TBI setup.

I would look through some of the engine swap threads that relate to TBI.

I've asked this very same question and not made much headway. Do yourself a favor and order two of the TOyota fuseable links....before one goes up in smoke...I've been there and let the smoke out of mine one time...about the time you feel the wire getting hot the fuseable link is toast.

 

[xxfullsailxx]

Was it me I'd look for the wire from the charge light at the charge relay's socket. Run a temporary jumper from that position to the I terminal on the alternator and then check for charge.

i think i'm going to try this, especially if i have to wait a couple of days for the relay. and i hear you about the 12v's...someone at a shop here in town i called said it was a "field" issue as well.

elbert-
i'm using the "painless" harness for the TBI motor. it didn't include any instructions/provisions for the alternator wiring...i just hooked it up the way i WAG'ed it way back when and to my surprise, everything worked just fine, so i went with it.

i guess i'm not so surprised by the possible relay failure given the age and mileage of the vehicle plus the extra demands on the system.

my fusible link was definitely affected also and i think what may have been going on was the loop connector to the fusible link wire (at the battery) had been getting worn and it was trying to push juice through just a few strands of copper...maybe this helped cause the relay failure?

i continue to pour over the wiring diagram, wondering what i might encounter next

...and appreciate the comments/input.

 

[ntsqd]

Interesting, your FSM's wire diagram shows the charge relay and my '84 Body FSM doesn't yet my FSM Engine Manual talks about it.

Once you've isolated which terminal you think it is at the relay's location check for no voltage when off and ~12 volts when on before installing the jumper.

 

[Elbert]

Kurtis on this board did a swap with a TBI...PM him to see what he did.

I would also get a GM shop manual for the year / model vehicle your engine is from so you can get the right infor as to what wire does what on the GM alternator.


https://forum.ih8mud.com/60-series-wagons/288395-tbi-swap.html

 

[xxfullsailxx]

ntsqd- your mini truck should have that charge light relay i think?

elbert-
i don't really WANT a whole shop manual for a '92 G1500 Chevy Van! but you're probably right...the chilton's sucks.

i will get a hold of kurtis, that's a good idea. it seems like most just bybass the toyota alt. wiring...my guess is he's running a one wire set-up like the rest of you...maybe that should tell me something?

mine is identical to this model except came from carquest:
New Tech N8165-3 - New Tech Replacement Alternators - Overview - SummitRacing.com

plus the FJ62 has different wiring...i have yet to identify the 3rd mystery white wire btw. it's on the truck, but not in the diagram.

AND i had it running for a year before these issues started. i don't even really know if the first alternator i warrantied was really bad since this charge light relay issue came about. i'm wondering if the problems didn't start with that worn fusible link...but i guess we'll see.

 

[Elbert]

so you had it running for a year now... when all of this happened you did not have a melt down, no burming wires....just something less than 13volts at the battery with the engine running? Present Alt tests fine, battery is good?...

Yeah I think most of us who have done swaps so far, or for the most part have been using FJ60. So I'm sure there is or may be soemwiring differences at the ALT...which is going to be an issue.

I belive there are some troubleshooting routines in the GM manual about what to look for regarding voltage readings at the wires that connect to the ALT, which might be helpful. But given all of that I would lean towards issues with the yota side then... of course looking for the dumb stuff like a blown fuse, loose connections, blown fuseable link, cut wire...etc. Assumption is that no other repair work preceded this issue?

the haynes and chilton manuals suck.

You might help yourself by posting up the wiring connections from the toyota side at the alternator and then the alt you are using and what wires run off it. Edit ( I meant to say pictures)

 

[xxfullsailxx]

so you had it running for a year now... when all of this happened you did not have a melt down, no burming wires....just something less than 13volts at the battery with the engine running? Present Alt tests fine, battery is good?...

yes, no, no, yes, yes and yes!

prior to this, i had been loosing juice in the battery on a regular basis.
if i didn't drive it every day, within two days, the bat would be dead.
i was just getting into trying to figure out where the battery draw was happening.

the other day while driving it (after having it on the charger overnight) i realized that my voltage was dropping and i had no charging going on...
made it home, tested both the bat and the alt and realized it wasn't charging...

i assumed it was the alternator, so i took it in for warranty replacement. got a new one, installed it, and still no charge...
looked at the system in general, fuses, wiring i had messed with and the fusible links, and realized the fusible link from bat to alt was worn, but not completely fried, although it did look like it had taken a little heat.

our local library (and i bet MOST libraries these days) has the "All-Data" automotive service database...i may go down there and copy the pages i need for the chevy.

 

[ntsqd]

For my engine swap I bit the bullet and ordered the GM manual from Helm. I expect to use the Z-28's Cruise Control down the road, so I knew that I needed more than just the basics.

I don't really know if "Patch" (the Mini) has the charge relay or not. My '86 FSM (for the turbo truck) shows an internally regulated Alt, but my '84 with the CS-130 on it was an external regulator and I've no idea where the 84's FSM is. Nowhere is a charge relay mentioned in the '86 FSM. When I made the Alt swap I simply looked for the wire that had 12VDC with the IGN on, and that would make the light come on when grounded and used it for the excite wire.

 

[xxfullsailxx]

no luck with the charge light relay...new part in, problem still the same.

taking Fluke in to the "professionals."

 

[Elbert]

For V-8 Swaps... for one I know some of the links in the FAQ are no longer valid.

I'm going to post up a thread to make an attempt to amass the correct information regarding wiring the alternator in regard to a GM V-8 Swap. Over the Christmas break I'll install my spare GM OEM CS140 alternator to verify tha tthe wiring is proper and then I'll documents with pics and narrative.
At min we should include the size and style of the engine...ie 5.7 vortec, we should also document the engine harness...ie.. painles, howell etc, and then document the model number of the alternator ie..CS130, CS 140...etc, and also document the model and year of the LC invovled.

Because just like you I've run into the same issues. I've asked multiple people and bascially struck out. There need to be some clear no BS pictures.... and narrative. Example " the two white wires that connected to the stud on the back of the yota alternator are now connected to teh XYZ of the GM alternator or they are incorporated into plug XYZ as noted in picture XYZ."

I feel your pain and that's why I went with a single wire alternator ...for one I did not have good informaition and two I wanted to get the truck running.

 

[xxfullsailxx]

okay, SO!.....for anyone still listening...

took my truck to the shop this afternoon, explained to the mechanic
(who is "known" for good electrical work) what i had going on:
the engine swap, the history and my current issue. he had the vehicle for a couple of hours.

conclusion:

he looked over my wiring, he looked over the wiring diagrams for both vehicles. all seemed in order.
just so happened the shop had an old gm alternator sitting around the shop,
so he installed it, wired it up the same way i had it, and PRESTO! 14+ volts.

turns out, the second alternator i got, which is a new-re manufactured unit from carquest;
which i had tested at two different shops and tested "good,"
was really not putting out any voltage when installed in the vehicle for whatever reason.

this little conundrum cost me: a week+ worth of time, $100 in relays and $100 for a mechanic to tell me what i already knew, but couldn't confirm.
not sure what the lesson is here...

SO THEN...

if you have a GM alternator with a 3-wire pigtail and you want to wire it into the Toyota wiring harness on an 1988 FJ62...

From the GM pigtail: To the Toyota harness:

Red wire: Inconsequential/not used
Brown wire: To the black/yellow for gauge & light
Black wire: To the yellow/white wire for 12v w/ignition on
Power Stud: Two heavy gauge white wires w/ ring connector

will post pictures tomorrow...and contribute to Elbert's thread because it would be helpful.

 

[Elbert]

here is a link

https://forum.ih8mud.com/60-series-wagons/543731-documentation-alt-wiring-v-8-swaps.html

Appreciate everyone with GM V-8 swaps to add to the knowledge base.

I hate to think about the $$ I've spent chasing my "@$$" on stuff like that over the years....