Toyota Nation Forum banner

1 - 20 of 20 Posts

·
Registered
Joined
·
33 Posts
Discussion Starter · #1 ·
I've been searching online but no luck yet.

Does anyone have a link to a wiring diagram for the Avalon 4th generation?
 

·
Super Moderator
1995 T100 2WD & 1993 MR2
Joined
·
9,403 Posts
Thats gonna be tough since Toyota holds all the copyrights to their products.
 

·
Registered
2018 Avalon XLE Premium V6
Joined
·
624 Posts
$20 will get you 2 days to download all you want as far as diagrams and repair manual information on the Toyota TIS site.

@sdspeed is right, I haven't seen many wiring diagrams in the wild.
 

·
Registered
2013 Toyota Avalon Limited W/Premium Package +
Joined
·
327 Posts
I got a 3 year alldatadiy sub for the price of one last fall. it's not the greatest site but you get longer than 2 days.
Check around for a coupon. If your only looking for something specific I can probably get you the section you need. There's a of of wires and diagrams in these computers on wheels.

Let me know if I can help you out. Or google for a code and see if one works.
 

·
Registered
2013 Toyota Avalon Limited W/Premium Package +
Joined
·
327 Posts
$20 will get you 2 days to download all you want as far as diagrams and repair manual information on the Toyota TIS site.

@sdspeed is right, I haven't seen many wiring diagrams in the wild.
Reason is because they stopped producing the manuals in PFD format. I think anything post 2009 is harder to get much of the manual from TIS in 48 hours.
 

·
Registered
Joined
·
33 Posts
Discussion Starter · #6 ·
Well that explains it then... had no idea.

I'm trying to trouble shoot the charging circuit. I just installed a 130amp replacement alternator in a 2013 Avalon but even though the alternator puts out 14.2v now, the battery light is still on... good battery, good fuse, good cables, good connections, and no faults on my scan tool. Car runs great except the battery light won't go out now.

Gary, if you could get a copy of the schematic for it, that'd be great. Thx !
 

·
Registered
2013 Toyota Avalon Limited W/Premium Package +
Joined
·
327 Posts
That's a whole different animal. Charging system is very basic. Finding the gremlin can be a major issue.

Here's the basic charging wiring diagram and alternator connectors at the end of the post

But the questions aren't as simple
  • Why was the alternator replaced? Dead? Over/undercharging?
  • Was the battery fully charged and load tested?
  • Was the battery light on or off before this happened?
  • Did you measure for A/C leakage from alternator? Meaning the diodes are not properly rectifying from A/C to D/C. New or refurbished alternators aren't tested properly these days and QC sucks.
  • Did you measure if while running there is a voltage difference between alternator output terminal and the reading at the battery posts (not the connectors and make sure you scratch the surface to get a good battery reading) Even 1/2 Volt not a good sign.
  • Is voltage fluctuating?
  • Have battery posts, terminals and extra wiring connected been checked and really well cleaned?
An outside good article on why this can happen:
Persistent Battery Light After Battery or Alternator Replacement

Here's a link to and old thread on testing but charging system is still pretty much the same basic system.
best way to test alternator

My suggestions:
Needed tools and products:
  • Multimeter with A/C and D/C range
  • Hand to wiggle wires and connections :)
  • A can of electrical contact cleaner
  • Vaseline
Check all of above questions off and ensure the answer is 100% yes.
Take off alternator plug spray both the wiring end and the alternator end with the contact cleaner. while off do a good visual inspection of the connector. Make sure the Main alternator output terminal is shiny and no corrosion. I would put Vaseline on it like one the on the battery terminals after connected even if it's covered by the boot. Check fuses and relay related to charging system including visual inspection for contacts in and out. Swapping then with another same one in the fuse box can sometimes help find a relay that SEEMS to work fine but has a little gremlin living inside causing intermittent issues. Problem clears and pops up elsewhere. If that ever happens stop and replace said relay immediately. No need to screw anything else up.

I'd suggest before doing anything to do the following skipping what you are 100% sure was done: Check for any DTC or pending codes. Clearing everything if any and disconnecting battery wait 10 minutes and start making sure everything is clean as a whistle. If battery not 100% fully charged do a slow charge. Max 2 amps till full charge. Then After all the cleaning, checking and reconnecting then you start her up and if light on start the test procedures listed.

Alternator connectors:
332960

332961


Diagram:

332962


Just incase: Symbols
332963

332964


This should give you something to start with. Hope it helps.
Let me know if you need anything else. But be patient it takes me hours to find and even just to post.
 

·
Registered
Joined
·
33 Posts
Discussion Starter · #8 ·
I'll make some more checks and let you know what I find.

Basically though, I started the car last Thursday morning and noticed the battery light. Next, I put the meter on the battery and only measured 11.9v at idle with stereo, heater, and day headlights on.

I disconnected the negative battery cable and the car died.

I measured no resistance from B36 to battery positive terminal with car off and no voltage drop with the car running.

It just looked like no output from the alternator so I bought a reman at Autozone - p#15542 130amp version.

After installing it, I measured 14.2v across the battery at idle and after turning on the heater, stereo, and high beams, I measured 14.1v.

Battery settles to 12.6v after sitting and starts the car immediately with no hesitation.
 

·
Registered
05 camry 07 tacoma
Joined
·
3,289 Posts
Killswitch- can you post the voltages on the IC regulator terminals with engine running.
Thanks.
 

·
Registered
2013 Toyota Avalon Limited W/Premium Package +
Joined
·
327 Posts
Good job in testing the drop.

Try this test first: unplug B37. Push car to ignition NOT RUN. Check if you have 5+ volts at pin 4 on the connector. Light should be also be off. If both conditions are met you have a bad regulator. Led goes straight to ground. at regulator.
 

·
Registered
2013 Toyota Avalon Limited W/Premium Package +
Joined
·
327 Posts
Killswitch- can you post the voltages on the IC regulator terminals with engine running.
Thanks.
Aren't they back sealed for weatherproofing?
 

·
Registered
2013 Toyota Avalon Limited W/Premium Package +
Joined
·
327 Posts
Yes, need to back probe or use wire piercing tool.
Considering it's regulating and charging correctly that rules out pins 1 and 2 supply and reference voltage. Pin 3 goes or comes to/from the ECM and I'm pretty sure if it was on the ECM side it would throw a DTC.

So my bet is via pin 4 LED to GND either a bad regulator since I doubt they test more than it working and regulating and probably not if the LED input works when they rebuild these things, or a short to gnd between the led and the plug at the alternator if the light is on then it's getting voltage through it and it needs to go to ground to close the loop to light. Or (which I highly doubt) he has a diode rectifying issues but I'm pretty sure that would probably mess up the electronics and throw a sh*tload of other random codes. These electronic modules don't take you throwing A/C current at the very kindly.
 
  • Like
Reactions: cj1

·
Registered
Joined
·
33 Posts
Discussion Starter · #14 ·
I removed the B37 plug and measured the pins on that plug after pushing Start twice, without foot on the brake pedal, to get the dash lights up.

Note: The battery light did go out with B37 disconnected.

1. 12.41v
2. 12.40v
3. 12.09v
4. 11.17v

The plug wires are wrapped up tight and very thin like 22awg so I didn't get to stab thru the insulation to make any measurements with B37 connected and car running.
 

·
Registered
05 camry 07 tacoma
Joined
·
3,289 Posts
Don't want to speak for Gary Q but i believe that the voltages look normal and that the charge light being on all the time indicates a fault in the alternator IC regulator.
Let us know if you change the alternator and if light stays off as it should.
 

·
Super Moderator
2020 Prius Prime Limited
Joined
·
4,844 Posts
Back to the request for the EWD (wire diagram): while TIS is only a 48 hour pass, that is all you need. Subscribe when you have many hours and simply print to PDF everything related to your car: the repair diagrams, the wire diagrams, all of it. It takes a few hours but then you have EVERYTHING you will ever need for your car. I did this for my 2009 Camry (443 files) and put it all in a folder on my computer. I am going to get everything for my 2015 4Runner and 2020 Prius Prime this way as well, just get all the docs and then I am set.
 

·
Registered
2013 Toyota Avalon Limited W/Premium Package +
Joined
·
327 Posts
Don't want to speak for Gary Q but i believe that the voltages look normal and that the charge light being on all the time indicates a fault in the alternator IC regulator.
Let us know if you change the alternator and if light stays off as it should.
Yes that's what I also assumed
.Although sometimes I can be somewhat confusing with TMI syndrome LOL. I thought that was a clear consensus. Don't know what Autozone warranty is but I'm pretty sure there's a fault in the regulator light circuit. Pin 3 BTW is a 12V source from ECM. Could even be unused like the 3 pin setup the previous models have and would still work fine.

P.S. Toyota clearly states not to disconnect battery while engine running. If done against recommendation and doesn't die. Stop engine immediately before you mess something else up.
 
  • Like
Reactions: Killswitch_11

·
Registered
2013 Toyota Avalon Limited W/Premium Package +
Joined
·
327 Posts
Back to the request for the EWD (wire diagram): while TIS is only a 48 hour pass, that is all you need. Subscribe when you have many hours and simply print to PDF everything related to your car: the repair diagrams, the wire diagrams, all of it. It takes a few hours but then you have EVERYTHING you will ever need for your car. I did this for my 2009 Camry (443 files) and put it all in a folder on my computer. I am going to get everything for my 2015 4Runner and 2020 Prius Prime this way as well, just get all the docs and then I am set.
That's a lot of f*ken work!
And I think it violates their terms of service.
@Killswitch_11 got what he needed for free with extra troubleshooting tips all wrapped up in one post. And I can pretty much guarantee the service manual doesn't offer the info and tips he was given. and if this doesn't resolve his issue with proper voltages and all that service manual will not be of much help. If he ever needs more we'll be happy to take the time to do our best to help as much as possible. since he's smart enough to do the basic proper tests before asking for help. And he actually follows advice to the letter! That's a guy worth taking an extra couple hours to try and help out.
 
  • Like
Reactions: Killswitch_11

·
Registered
Joined
·
33 Posts
Discussion Starter · #19 ·
Yikes... I thought replacing this alternator 1 time was bad enough.

Autozone has a good warranty on it so that part won't be an issue.

Thanks all
 

·
Registered
2013 Toyota Avalon Limited W/Premium Package +
Joined
·
327 Posts
Yikes... I thought replacing this alternator 1 time was bad enough.

Autozone has a good warranty on it so that part won't be an issue.

Thanks all
Yeah it sucks when you actually test properly replace the part and it is most likely defective because we assume stuff works when we buy it and most electrical parts are bloody expensive and not returnable. (minus the old school battery disconnect while engine running. which you got to admit is an extremely effective test LOL)

I'm assuming you'll update us on the outcome when you get this resolved. Helping is fun but knowing if the help resolved the issue is nice and if something else was the cause it helps us learn something new.
 
  • Like
Reactions: Killswitch_11
1 - 20 of 20 Posts
Top