Body ECU test bad, or does it?

[IBallEngineer]

This post is mainly directed [MENTION=10169]TheDurk[/MENTION] but I figure I should share my reservations about condemning a body ECU and as always entertain any insight others may have.

Working on a 1999 Limited. Owner does NOT have a remote/fob, but thinks he had one at one time. I do NOT know if his truck has the engine immobilizer.

His complaint is the door locks will UNlock the doors, but not lock the doors. When I attempted to lock the doors from the master switch, there is no clicking or any noise from any of the actuators. This leads me to believe the actuators are not the problem. (Disclaimer, I have not actually tested any of the actuators) So I pulled the switch, and disconnected the connector. I applied ground to the Red/White wire at Term 6, got no action. Applied ground to Red wire at Term 12 and door locks unlocked.

From here I disconnected 1H at the Body ECU, tested continuity to the terminals at the switch, good continuity. Tried to directly ground the red wire at the body ECU, but without hurting it I don't think I made a connection. But I'm about 99.99998 percent certain the wiring is fine, but the Body ECU is not actuating in the lock direction. I did not test the switch from the passenger side because they ground the same terminals at 1H.

At this point I was running out of time, so I jumped ahead a little, bad idea. I tried the key in the cylinder in the passenger side, same results, will unlock, but not lock. In the Driver's side, the cylinder unlocks just fine, but the cylinder would not turn in the "lock" direction. I quickly pulled the door panel to look for a mechanical failure, found none, so I pulled the handle and looked closely at the cylinder, still couldn't see why it wouldn't turn. I did not try grounding the individual circuits from the key.

I also did not test the unlock detection switch circuits, only the front doors have them, but I never got to that. I should have done that when I had the Body ECU out.

I also tried a used Body ECU I got for $20 from a guy, but I don't know what year it came out of although I believe a 2000. Thing is, the door lock functions remained unchanged. AND it wouldn't start, so I believe it had the immobilizer in that used Body ECU.

So my question is, should I confirm the courtesy door switches and door unlock detection switches all operate normally before condemning the Body ECU? And... what role does the lock cylinder operation play in this? I took the switch off the cylinder and manually turned it but the operation was unchanged.

I am bummed that I was rushed, he told me he needed actuators and I believed him, I have new motors I was saving for my own truck. So I only blocked out 2 hours and told him he could just hang out. I'll have him leave it with me one day and sort through this, but if it turns out it IS the Body ECU, I'll have to order one.

What says you?

 

[TheDurk]

The lock cylinder thing is weird, so certainly excites suspicion. I tried all kinds of ways to see if there is an interlock on my '99 (factory wireless, no immobilizer, no alarm) and there just isn't. The key will turn to lock and all closed doors will then lock (on second turn) even with the driver door open or the passenger door open. I even tried using my spare key to turn ignition ON and the other key still locked all the doors (on second turn). So that's a head-scratcher. Also, the door switch will still lock all the doors even if driver's door is open, so I don't think there is any interlock that interferes with the lock process.

Do the actuators get 12v+ on the blue/white wires?

What happens if you apply 12V+ to the blue/white wire at Pin 7 on 1H and ground to Pin 3 (black/yellow)? That should lock all doors except driver's which has its own ground. Reverse and they should unlock. If that happens, actuators are obviously good. Then I'd apply ground directly to Pin 10 on 1H where the red-white wire goes. At this point, I'd also try grounding the brown-white wire at the Pin 1 on the key switch. You would need to ground it twice in close succession for the Body ECU to signal all actuators. This goes to a separate lock terminal on the Body ECU. If no action either way, I'd say it's body ECU without a doubt.

 

[IBallEngineer]

The lock cylinder thing is weird, so certainly excites suspicion. I tried all kinds of ways to see if there is an interlock on my '99 (factory wireless, no immobilizer, no alarm) and there just isn't. The key will turn to lock and all closed doors will then lock (on second turn) even with the driver door open or the passenger door open. I even tried using my spare key to turn ignition ON and the other key still locked all the doors (on second turn). So that's a head-scratcher. Also, the door switch will still lock all the doors even if driver's door is open, so I don't think there is any interlock that interferes with the lock process.

Do the actuators get 12v+ on the blue/white wires?

What happens if you apply 12V+ to the blue/white wire at Pin 7 on 1H and ground to Pin 3 (black/yellow)? That should lock all doors except driver's which has its own ground. Reverse and they should unlock. If that happens, actuators are obviously good. Then I'd apply ground directly to Pin 10 on 1H where the red-white wire goes. At this point, I'd also try grounding the brown-white wire at the Pin 1 on the key switch. You would need to ground it twice in close succession for the Body ECU to signal all actuators. This goes to a separate lock terminal on the Body ECU. If no action either way, I'd say it's body ECU without a doubt.

Thanks, I need to follow through with what you are suggesting, as well as the unlock detection even though I don't understand it's relation. You pretty much are of the same mind set as I am, I would have condemned it already if I had the time, and if the key cylinder worked.

Do you know how to tell if this vehicle has the engine immobilizer? I can always call Toyota parts, but I feel guilty since I won't buy it from them. I do have the VIN and date of mfg.

:noidea:

 

[TheDurk]

Thanks, I need to follow through with what you are suggesting, as well as the unlock detection even though I don't understand it's relation. You pretty much are of the same mind set as I am, I would have condemned it already if I had the time, and if the key cylinder worked.

Do you know how to tell if this vehicle has the engine immobilizer? I can always call Toyota parts, but I feel guilty since I won't buy it from them. I do have the VIN and date of mfg.

:noidea:

Well, you can tell by looking at the key. The unchipped master is black and really has no room for a chip. The chipped one is greyish and thicker in the body. Unchipped is flat black and has a wide hole. VIN won't help unless you are a dealer and can pull the build sheet. You can't do it by just decoding the VIN; there is no field for that. Only other way I know is the p/n off the Body ECU.

Chipped:

Unchipped:

 

[Jhelms]

I just went through all the same stuff with my 01 limited with immobilizer. I ended up replacing the in cab fuse box which contains the BCM. The control module is part number specific to an immobilizer equipped vehicle vs a non.

Same EXACT symptoms. I could usually get the doors to lock fine (solenoids are a bit sticky so need attention) but they would not unlock. Sometimes they acted like they were struggling to unlock but would not. Relay did test good and was functional so the issue was deeper than that.

Sadly and $500+ later, I had the solution. You have to buy the whole damn fuse box, but all you need is the BCM PCB out of the fuse box.

I also went down the rabbit hole of trying to diagnose and repair the old BCM and it did not work. The relays would all function but the issue seemed to be in one of the controller IC's.

Here is the culprit under the drivers dash, lower left hand corner with the cover off.

I am confident I could have found a work-around for the issue if I had more time. But decided just to fork over the cash and get my 4runner back on the road.

I kept the old unit around as I want to get back to it and mess with it more in the future.

 

[IBallEngineer]

I just went through all the same stuff with my 01 limited with immobilizer. I ended up replacing the in cab fuse box which contains the BCM. The control module is part number specific to an immobilizer equipped vehicle vs a non.

Same EXACT symptoms. I could usually get the doors to lock fine (solenoids are a bit sticky so need attention) but they would not unlock. Sometimes they acted like they were struggling to unlock but would not. Relay did test good and was functional so the issue was deeper than that.

Sadly and $500+ later, I had the solution. You have to buy the whole damn fuse box, but all you need is the BCM PCB out of the fuse box.


I am confident I could have found a work-around for the issue if I had more time. But decided just to fork over the cash and get my 4runner back on the road.

I kept the old unit around as I want to get back to it and mess with it more in the future.

This one the symptoms are reversed, it will unlock, but not lock. These things are all over the internet for less than $300, did you pay for installation or did you pay full retail?

:eyebrows:

 

[Jhelms]

This one the symptoms are reversed, it will unlock, but not lock. These things are all over the internet for less than $300, did you pay for installation or did you pay full retail?

:eyebrows:

miss-read it, apologies. Yeah they sure are all over - all used with a LOT of miles / age on them! And no, I do not pay anyone to install anything for me except window tint :bounce:

$525 out the door for a brand new module - hopefully peace of mine for the next 225K miles or more which is how long the first lasted

Also, you can make it quick and easy, the PCB will pull out of the housing so you do not have to swap the entire fuse box. Whatever works for you though

Just a hint, since you said you could not hear a click, likely one side of the door lock relay has failed. It has dual coils. The two poles by the connector side are normally closed, the two poles towards the center of the relay are normally open. The door lock relay is a non standard / not off the shelf unit made by Taiko model TB2-100P. One can sub in a standard SPST or SPDT relay if one side of the relay fails (with some custom rigging of course). This particular Taiko relay is known across several makes and models to fail. Toyota later switched to a panasonic version with the same footprint in the module if you buy a new replacement.

 

[IBallEngineer]

miss-read it, apologies. Yeah they sure are all over - all used with a LOT of miles / age on them! And no, I do not pay anyone to install anything for me except window tint :bounce:

$525 out the door for a brand new module - hopefully peace of mine for the next 225K miles or more which is how long the first lasted

Also, you can make it quick and easy, the PCB will pull out of the housing so you do not have to swap the entire fuse box. Whatever works for you though

Just a hint, since you said you could not hear a click, likely one side of the door lock relay has failed. It has dual coils. The two poles by the connector side are normally closed, the two poles towards the center of the relay are normally open. The door lock relay is a non standard / not off the shelf unit made by Taiko model TB2-100P. One can sub in a standard SPST or SPDT relay if one side of the relay fails (with some custom rigging of course). This particular Taiko relay is known across several makes and models to fail. Toyota later switched to a panasonic version with the same footprint in the module if you buy a new replacement.

Are the legs soldered?

:ranger:

 

[Jhelms]

Directly to the PCB. You have to de-solder / remove the stock relay and solder in a pair of relays - or a DPDT. The conformal coating is difficult to work with so you need a good soldering station to de-solder the relay and a little bit of no clean or water soluble flux to make it flow properly. Not a task for solder braid.

The controller IC failed in mine or it would have been a simple task if it was just the relay - which is what yours sounds like.

 

[PoshSnoop]

Thanks guys. Of all the "doors will unlock, but not lock", "body ecu" threads, yours is the shortest, simplest, most detailed, and most helpful to me. Looks like I'll be forking over 500 or so numbers to Toyota in hopes of getting a fresh body ECU with the Panasonic version of the door lock relay. Before my inner cheap bastard squeaks his last on this repair, are you aware of any Toyota OEM Body ECU suppliers that sell these things new for significantly less than $500? Mr. Google's not showing anything below $450.

...and apologies for floating an old thread...

 

[bruised]

Thanks guys. Of all the "doors will unlock, but not lock", "body ecu" threads, yours is the shortest, simplest, most detailed, and most helpful to me.

...and apologies for floating an old thread...

Respectfully, I have to disagree with JHelms, I desoldered the relay and installed a new one with solder wick braid dipped in flux. I also wanted to post a short DIY so people can get an idea of if it is within their capabilities.

I have a 99 that would unlock but would not lock using the fobs or any interior switches. I could hear the relay click when trying to lock.

I will start with a warning, this is not easy and not quick, took me around 3 hours. Only do this if you are willing to buy yourself a new board should you ruin yours. I gave this a try as it seemed worthwhile to maybe save $500.

Start by removing the dash panel under the steering wheel (4 bolts)

The body control module is the white box to your left, disconnect the two connectors on the front of the box and remove the cover to expose the PCB board. The board is held in with 4 screws at the corners and 4 clips in the box. Remove/un-clip these and then gently work the board out from the connector along the left side.

Once the board is out find the Taiko TB2-100P relay, this is what gets removed. I could not find one of these or the panasonic replacement the newer boards use so I used a Taiko TB2-160. Same foot print and voltage rating, slightly higher coil resistance.

Using your wick generously dipped in flux remove the solder from the following points. This is the hardest and most time consuming part of this.

Once the solder is out gently rock the relay out. Stick your new one in and apply solder carefully, don't apply too much and spill onto other components or pathways.

Installation is reverse of removal.

 

[3bears]

wonder how much that body ecu would be through aryama

 

[IBallEngineer]

Respectfully, I have to disagree with JHelms, I desoldered the relay and installed a new one with solder wick braid dipped in flux. I also wanted to post a short DIY so people can get an idea of if it is within their capabilities.

I have a 99 that would unlock but would not lock using the fobs or any interior switches. I could hear the relay click when trying to lock.

I will start with a warning, this is not easy and not quick, took me around 3 hours. Only do this if you are willing to buy yourself a new board should you ruin yours. I gave this a try as it seemed worthwhile to maybe save $500.

Man, first off, great job that you were able to do what you did. But I'm going to go out on a limb here and say you aren't from 'round these parts are ya'?

No offense intended here, but I don't think you are disagreeing with [MENTION=123173]Jhelms[/MENTION] at all, he said it would be hard, you said it it would not be easy. Sure he said a desoldering station is needed, you said a flux coated wick could handle it. Both are true, in as much as they both would work. But based on your post count, you aren't very familiar with the level of FEAR the average forum member has of electrical and electronics. They run like scared rabbits if their turn signals don't work, no really. Use a DVOM, shoot they start googling to see if that is a new sort of optical drive for their Xbox! Soldering pencil? All they have is grandpa's Weller gun from 1964, still in the metal case and sitting on a newspaper clipping from the Nixon era. Flux my wick? I'm pretty sure most here think that is a euphemism, Hey I might have to use that one.

Seriously though, I have done some wicking, with some success and I have to say I'd try it for sure. Always good to see a different view, and learn from different experiences. Where did you source the relay? I fear the proximity of other circuits on PCB's, but If I have a failed ECU anyway I will consider taking the chance. My wife's 99 won't turn off the Rear Window Defogger, so I pulled the relay. The relay is grounded at the Body ECU, wonder if that too is a relay or an integrated circuit. Imma gonna WRECK con oiter that furst chanz I get, maybe March, or June.
layball:

 

[BrianSD_42]

I've got an extra ecu sitting in toolbox, if anyone wants it pm me. $35.00

97 Limited Auto 4WD

 

[bruised]

Man, first off, great job that you were able to do what you did. But I'm going to go out on a limb here and say you aren't from 'round these parts are ya'?

Dang, my newb is showing? :doh:

Sure he said a desoldering station is needed, you said a flux coated wick could handle it. Both are true, in as much as they both would work. But based on your post count, you aren't very familiar with the level of FEAR the average forum member has of electrical and electronics. They run like scared rabbits if their turn signals don't work, no really.

I guess I shouldn't but I find this surprising, I come from the german sports car world where everyone is a wuss, but it seems these 3rd gens are basically unbreakable and most are worth less than 5-6k. Maybe its just that electricity is dark magic.

Where did you source the relay?

Back on topic, there were tons of the TB2-160's on ebay. I ended up buying a 5 pack from a distributor here in the states that said they were certified with Taiko (although real and fake both come out of china anyway so who really knows) that was about 4$ per. Still have 4 left if anyone wants to take them off my hands.

 

[PoshSnoop]

...level of FEAR the average forum member has of electrical and electronics...

this average forum user ain’t skeered (much). i’ve misdirected numerous electrons in my time. aside from the fried wiring harnesses, engine bay fires, exploding batteries (with subsequent baking soda applications), zotted equipment, and them tingly feelings, electrons are our friends!

 

[Buckaroo]

this average forum user ain’t skeered (much). i’ve misdirected numerous electrons in my time. aside from the fried wiring harnesses, engine bay fires, exploding batteries (with subsequent baking soda applications), zotted equipment, and them tingly feelings, electrons are our friends!

The problem is you can hardly see those dang electrons, and they move so fast....

Buckaroo

 

[IBallEngineer]

The problem is you can hardly see those dang electrons, and they move so fast....

Buckaroo

And which direction are they moving anyway? The "hole" theory is full of holes!:biggrin2::drum:

 

[Thenley83651]

I've got an extra ecu sitting in toolbox, if anyone wants it pm me. $35.00

97 Limited Auto 4WD

Not sure how to send PM on here but I’d buy it.

 

[Brian.]

Not sure how to send PM on here but I’d buy it.

While he's still around, that post was from 4 years ago....

Car-Part.com--Used Auto Parts Market

search there, I've seen a few for as low $35 (probably before shipping).

BTW, there are 7 different body ECUs ~ unless you're just scavenging parts, you'll want to make 100% sure you're getting the right replacement. And if you have an immobilizer system, you'll need to deal with that too.

Hope you have some soldering experience... I destroyed one of these with a $30 pencil soldering iron before buying a better quality soldering station.