Toyota BCM replacement

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jhellwig

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It looks like the BCM on my wifes van biy the dust. Does anyone know if these have to have a vin specific program put in them or can they just be swapped?

The issues we have are multiple warnings for various systems like. VSC, ABS,TCS, brakes TPMS power steering and a bunch of warning lights. It doesnt charge and the power windows and turn signals dont work. I did check all the fuses and found none of them were blown.
 
Have you done any diag beyond checking fuses? There are likely to be multiple fault codes in those modules which are driving the warning lights.
 
BCMs rarely go bad on Toyotas. Unless it got contaminated by water or a power surge was present.

Did you check the battery, grounds and the other inputs it takes in like door/brake switches?
 
I checked for codes but none were set. My scanner does not have the advanced toyota diagnostics though. It looks like toyota makes a program that I could get to diagnose it but the one place I saw it was 1500 for it.

I am still trying to find a mechanic to work on it as I dont know much about Toyota's. The dealer in town is not recomended by anyone so I have to haul it somewhere. One mechanic looked at it and said it was above them.

BTW this is a 2014 sienna in case anyone cant see my signature.

All the switches other than the power windows apprear to work but I do realise that some of the switches might have multiple contacts.
 
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2010 Sienna 3.5 V6
I've got 2 codes;
U0126
lost communication was steering angle sensor module and
C1201
notations
1 brake boost sensor, circuit range performance
2 engine control system.

This is somewhat beyond my knowledge, so from recall
Next, was watching a video on someone that was working on a can-bus in there is 2 resistors, one resistor that went bad made the resistance between the 6 and the 14th in on the obd2 connector read at 120 ohms instead of the 60 ohms it should have been reading. Basically everything relying on the can-bus is not able to communicate without the correct resistance ohms. I think they were working on a BMW, can't remember, but they must have swapped out the part with the bad resistor as I recall it.

I've checked my pins and I get right around 100 ohms to maybe 111, I don't remember exactly what I bought another brake control module thinking I could easily put it in but it's so close to the fender wall that it won't be easy without taking the brake lines loose to change just the computer part of the module.

I don't know that this helps with your your BCM or not, but I figured I'd throw that out there just in case.
 
My $30 eBay scanner can read previously referenced codes, Faslink M2, plug into OBD2 port and software runs on phone, or in my case Samsung Tablet, and I also have Innova 3160e, $230(Walmart). I think the newer Innova's are also cross referenced under Craftsman and a whole lot cheaper on eBay, but there is all kinds of new stuff just coming out, research and order immediately and you could be able to get something delivered to your front door by the weekend, narrowing your search area can bring up a closer seller where the price is close enough to the cheapest that it's worth it for a shorter shipping distance.

Which reminds me to order some Rock Auto calipers, I'm planning on bleeder screws not cooperating as and when I ever get to change out my ABS module, as I should have previously referenced what I was changing. My newest code reader, Faslink P1, is supposed to do the ABS bleed, and I I tested it with out actually bleeding the lines, it did activate the ABS, it's software is funny, because it seems it was sourced through another company and their similar product is
HUMZOR NexzDAS Lite
not that I am recommending it, just putting it out there as an option, but there so many new code readers I'd say research and shop around, I just got mine and haven't used it enough to have a experienced/educated opinion.
 
You said it doesn't charge? The alternator has a clutch built into the pulley that I've seen fail a few times. Check your charging system voltage. The "Christmas tree lights" on the combination meter is a sign of low alternator output
 
Are you getting 14VDC across the battery with the van idling? If it's less, you can get combinations of what you are experiencing. Your BCM may be fine.

I'm hoping the shops that turned you away atleast checked your battery and charging system.
 
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Originally Posted by Supersonic
2010 Sienna 3.5 V6
I've got 2 codes;
U0126
lost communication was steering angle sensor module and
C1201
notations
1 brake boost sensor, circuit range performance
2 engine control system.


Do you have access to a scan tool that can interpret the DTC sub-data Toyota uses? You are probably right on the money with checking the CAN bus for the right resistance of 120ohms, but unless something physically damaged the car's wiring that contained the CAN bus wiring pair, or someone tried to install a aftermarket remote start/alarm or radio interface that taps into the CAN bus, it's a pretty robust network.
 
Originally Posted by mehullica
You said it doesn't charge? The alternator has a clutch built into the pulley that I've seen fail a few times. Check your charging system voltage. The "Christmas tree lights" on the combination meter is a sign of low alternator output


I forgot about the clutch thing. I will check that.

Originally Posted by JTK
Are you getting 14VDC across the battery with the van idling? If it's less, you can get combinations of what you are experiencing. Your BCM may be fine.

I'm hoping the shops that turned you away atleast checked your battery and charging system.

I am not getting 14 volts. That is how I know it ia not charging. In the mean time of it setting in my garage till I took it to my first mechanic one of my kids decided to play in it and ran the battery dead. That is how I found out it wasnt charging after I jump started it and shortly after I started to drive all the displays went out and I barley managed to limp it back to the driveway. Charged it up and ran it while hooked up to the charger and that didnt change anything. Voltage was aroind 12.8 when I tried that as it was only a 15 amp charger. I figured being on a charger or jumped to another vehicle might trick the computer into thinking the alternator was working and clear the errors but it didn't. I am going to try tonight to get the plug off the alternator and jump excitation voltage to it to see if it will charge.

I hate electrical on vehicles. I am an electrician and it still messes with my head some of the ways they do things.
 
Does anyone know the wiring for these alternator. I have voltage on 3 of the 4 wires in the plug on it when the key is on. I am woundering if the fourth pin needs power for it to work.

I hooked my charger to the output of tge alternator to see if there is a CT that the wire goes through but it didnt change anything.
 
Quote

Do you have access to a scan tool that can interpret the DTC sub-data Toyota uses?
but unless something physically damaged the car's wiring that contained the CAN bus wiring pair,

Not that I am aware of, but haven't used the new Faslink P1 enough to know it's capabilities, just got it because of the promise of ABS bleeding.

For my can-bus issue I am only guessing there is a resistor in the ABS module that is the problem because of the video I watched, and being the used part was cheap, I was going to swap it. The ABS module seems to have been an issue on other Toyota's of similar vintage. The Sienna location of the ABS Module makes it difficult to swap, may be a blessing so I don't touch it at all...

My one other thought was to figure out a way to add a resistor somewhere into the can-bus that is easily accessible. Of course, I should probably leave it alone and just drive as is.

This is the video I was watching, starting at 22 minutes gets to the point;
Can-bus Trouble
 
Originally Posted by jhellwig
Does anyone know the wiring for these alternator. I have voltage on 3 of the 4 wires in the plug on it when the key is on. I am woundering if the fourth pin needs power for it to work.

I hooked my charger to the output of tge alternator to see if there is a CT that the wire goes through but it didnt change anything.


I hate electrical on vehicles. I am an electrician and it still messes with my head some of the ways they do things."



You are an electrician? And asking these basic questions? What level of test equipment and and scanner?

Do you have a service manual, wiring diagram, or schematic?

As stated, the BCM rarely is the fault. It is the numerous signals and sensors, wiring, connectors, etc. feeding it info that fail.
 
Last edited:
Originally Posted by user52165
Originally Posted by jhellwig
Does anyone know the wiring for these alternator. I have voltage on 3 of the 4 wires in the plug on it when the key is on. I am woundering if the fourth pin needs power for it to work.

I hooked my charger to the output of tge alternator to see if there is a CT that the wire goes through but it didnt change anything.


I hate electrical on vehicles. I am an electrician and it still messes with my head some of the ways they do things."



You are an electrician? And asking these basic questions? What level of test equipment and and scanner?

Do you have a service manual, wiring diagram, or schematic?

As stated, the BCM rarely is the fault. It is the numerous signals and sensors, wiring, connectors, etc. feeding it info that fail.

Well considering it is a car that I have never worked on before and not an industrial automation system that I have been working on for years I might have some basic questions for people that have worked on them before. If I had a wiring diagram or was able to find one do you think I would be asking?

I finally got the communication cable and the Techstream software on my computer and now I see I have a p0500 and a p0705 code set. Now I at least have a direction to look.
 
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I also have a u0129 code which is loss of communication to the brake system control module. Makes sence since I cant acess that ecu in Techstream. Looking like a possible can bus issue now unless that module died.

Looks like I am going to have to take it to a dealer since Google isnt turning up any answers.
 
Well we took it to the deal that no one recomends and they say the alternator is bad. Didnt quote me to bad of price for replacing it considering the front end has to come off to do it.

Of all the diagnostics and error lights there was nothing about the charging system in any of it.
 
had lots of dtc's set when my alternators regulator went bad from improper sealing at the factory.
dash lights galore and indicating all doors opening randomly.
it was alternating all right.
from no charging to around 17v.
causing all sorts of driveability issues along with turning the cluster into a christmas tree.
all over having to wash a huge colony of ants out of the car.
i sprayed the tree they were living in and they moved into the accord.
a $15.00 ebay regulator module and 10 minutes to replace fixed everything.
didnt even have to pull the alt.
 
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