ECU is located behind the dash board and just to the right of the steering column. square metal box about 12cm x 12cm x 4cm.
KZJ78 95 Flashing Hub lock light (2 Viewers)
- Thread starter Lomoski
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Haha your car is winking at you! So you must have front and rear LSDs? didn't realise there were models like that. I jacked mine up on one side in my driveway and engaged 4WD - two wheels move as I have centre diff lock only.
The ECU is roughly underneath the steering column. I was able to identify it because there was a loud relay clicking that matched the flashing light.
I have no idea why your lights would be blinking but I will say, if it ain't broke don't fix it!!
Mine must be in a different place
I have no idea if I have limited slip diffs or not. I know when the car was lifted with all 4 wheels in the air and the 4wd system fully engaged, all 4 wheels were turning. With the hubs engaged and engine off, spinning one front wheel would cause the other to spin opposite direction, and disengaged the front wheels could be manually spun at will.
Out of curiosity, why did you disconnect a wire at the ECU to stop the hub lock indicator blinking instead of removing a bulb from the instrument panel? Was it for operational reasons or you just found the ecu method easier to accomplish? Without knowing what else the ecu might be using that signal for, I’m inclined to just pull the light bulb.
Okay, your front wheels are operating as normal - the same as mine. No LSD in the front, only one wheel gets power with 4wd system engaged.
I unplugged the ECU after I took the advice of a member on here with experience of the system - oldblue. He's v knowledgeable. There's no change to anything else that's running.
As far as I know there are no 70series Prado Landcruiser's that came out with LSD, only some with a rear electric locker.
Does anyone have a FSM with troubleshooting logic for the flashing hub light indicator? Or an EWD that shows what circuits and sensors even exist for the hub and transfer case? Before I go digging around trying to isolate why mine is wrong, I'd love to get a better understanding of what signals the ECU and indicator lights are even processing. I know FSMs for the US cars include flow charts for diagnosing problems, but I've searched everywhere for equivalent FSMs for the KZJ78 and have found nothing. Is there a US spec Toyota that used the same or similar electric hub locker where that flow chart might exist?
Alternatively (if nobody has an EWD or FSM with the electric hub locker pages), does anyone know what sensors are in the hub locker and what signals are being sent back to the ECU to control the indicator lights?
Alternatively (if nobody has an EWD or FSM with the electric hub locker pages), does anyone know what sensors are in the hub locker and what signals are being sent back to the ECU to control the indicator lights?
This is all I have.
Thx for the diagram btw.
Before I open this up or start spending money to convert to manual hubs, I wanted to do as many non-invasive tests as I could to narrow down the potential flaws. I opened the connector next to each of the hub lock motors and connected my multimeter to see what I could find. In testing resistance on the actual hub assembly (the wheel side of the connector), I measured one side at 7 ohms and the other side at about 770 ohms. Both hubs should theoretically be in the unlocked position. I tried to test voltage on the vehicle side of the connector to see what signal the ECU was sending, but found nothing on either side. I don't know if this was a valid test, however, as a) I was working by myself and could not press the hub lock button while watching the voltage readout, and b) with an open circuit, maybe the ECU knows not to send a voltage to the motors.
It does seem like the resistance of both hubs should be the same if they are both in the unlocked position, so I'm inclined to thing one of them is either not all the way unlocked or one of them is broken or has a dirty contact inside. My suspicion is the one with the higher resistance is the problem, but that's purely a guess as I have no idea what the resistance of a hub motor should be.
Can anyone explain how the ECU is functioning? And from that, are there better tests I can do to figure out whether the problem is the ECU or a motor (and which one)? The ECU has three possible states to send to the hub lock indicator - off, on, or blinking - but it has only 2 wires, ML1 and ML2, from which to figure out what state it's in.
Part of this is just because I want to understand how this thing is working, but part is also because I don't want to start opening things up or replacing parts randomly until I accidentally fix the problem. It seems like I should be able to narrow down the problem if I can figure out how the ECU is processing the information and what measurements I should be seeing on different wires.
Before I open this up or start spending money to convert to manual hubs, I wanted to do as many non-invasive tests as I could to narrow down the potential flaws. I opened the connector next to each of the hub lock motors and connected my multimeter to see what I could find. In testing resistance on the actual hub assembly (the wheel side of the connector), I measured one side at 7 ohms and the other side at about 770 ohms. Both hubs should theoretically be in the unlocked position. I tried to test voltage on the vehicle side of the connector to see what signal the ECU was sending, but found nothing on either side. I don't know if this was a valid test, however, as a) I was working by myself and could not press the hub lock button while watching the voltage readout, and b) with an open circuit, maybe the ECU knows not to send a voltage to the motors.
It does seem like the resistance of both hubs should be the same if they are both in the unlocked position, so I'm inclined to thing one of them is either not all the way unlocked or one of them is broken or has a dirty contact inside. My suspicion is the one with the higher resistance is the problem, but that's purely a guess as I have no idea what the resistance of a hub motor should be.
Can anyone explain how the ECU is functioning? And from that, are there better tests I can do to figure out whether the problem is the ECU or a motor (and which one)? The ECU has three possible states to send to the hub lock indicator - off, on, or blinking - but it has only 2 wires, ML1 and ML2, from which to figure out what state it's in.
Part of this is just because I want to understand how this thing is working, but part is also because I don't want to start opening things up or replacing parts randomly until I accidentally fix the problem. It seems like I should be able to narrow down the problem if I can figure out how the ECU is processing the information and what measurements I should be seeing on different wires.
When testing the plug ( on the hub side) , could the different readings be that one side hub could have good carbons and the other side have no carbons and just the springs running metal to metal on the copper slip rings
I have a few motors laying around from when I've done conversions, I could measure the ohms if that helps tomorrow NZ time.
That may help, but I'm in no hurry. The car woks fine for normal driving, so I have a long list of higher priority projects I can do ahead of the hub lock. I'm hoping with a little late night research I can figure out a quick and easy solution. Thx!
I'm not a sparky, Is this what you require ?
I have to admit I'm not 100% sure. I've taken a number of EE classes back in college, but those taught me the math about electrical circuits, not how to actually get my hands dirty and actually do something in the real world. That said...
I interpret your measurement as the motor being 8 ohms, that based on the first photo where your multimeter is set to 2000 ohms. That would be somewhat consistent with one of the two I measured on my car at 7 ohms (the other measured at about 7k ohms. Of course I was measuring mine from the connector on the wheel side, so I was measuring the total resistance of the whole circuit through the connector, wires, brushes, and motor where your measurement was purely of the motor itself. I think it's still good guidance.
I see at least a couple possibilities on mine. One, the hub I measured at 7k ohms might have dirty contacts or damaged brushes that are causing problems so the motor is not getting the voltage and current it needs to do it's job. Two, the hub might be fine, but is stuck in some kind of open position where one of the brushes is not completing it's circuit.
I think I have enough confidence in the potential problem that it's worth opening the one I'm measuring at 7K ohms and see if I notice anything... bent or broken brushes, too much grease or grime near the contacts, etc. Now I just need to get the time...
Just remember to pin back the carbon brushes when refitting the hub body.
Does anyone have a picture of what the brushes are supposed to look like? I've searched and haven't found one. Also a photo of what the slip ring should look like before I put the hub back on. Those would help me recognize good from bad when I pull the hub and finally inspect this thing (my hub lock indicator has been winking at me for a couple months now... getting annoying enough I'm about to finally open the thing up).
The condition of the brush's don't have any effect on when the hub light blinks.
I've converted hubs with good and bad brush's and the hub light still blinks
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I've converted hubs with good and bad brush's and the hub light still blinks
Thanks for that diagram... it gives me a little idea what those brushes should look like.
I guess I'm still struggling to understand then... broken or bent brushes don't cause the indicator light to blink? What conditions do cause it to blink then? What is the ECU seeing that cause it to signal the indicator light to be off, on, or blinking? There are only a couple wires going to the ECU, so there are not many possibilities of what it's seeing. It sounds from what your saying that the ECU can somehow tell whether the hubs did fully engage or disengage, and that's it?
There are two wires going to each hub. Is one of them a ground and the other is a hot (In other words, they are two sides of a single circuit)? Or the hub motor is grounded through the axle and other parts and one wire is an "engage" wire and the other is a "disengage" wire (two circuits both connected to grourd)? I'm inclined to think its a single circuit since when I undo the clips behind the hub and test the hub for continuity, the two wires appear to form a circuit with a resistance of somewhere between 7 and 13 ohms (I get a different reading on each hub). If it's one circuit, I'm not sure what the ECU would see to tell it the hub has fully engaged or disengaged. Maybe when the hub hits it's end point and stops the motor from spinning, the ECU sees a current spike from the motor? So if you push the hub lock button, the indicator light starts blinking to indicate something is chaining and if it senses the motor was stopped it knows it worked and changes the indicator light to either on or off, depending whether you were trying to engage or disengage?
Sorry if this is going down a rabbit hole, but I get frustrated when things that should be solvable aren't solved.... makes me want to dig in and figure out what's going on. Hopefully it would lead to a usable solution.
Has anyone heard of this solution? Quick summary - this guy shows that putting a 50 ohm resister at each wheel to essentially replace the missing motor after a manual hub conversion would stop the indicator light blinking. He barely shows it in the video but I surmise that the hub indicator light is off when the button is off and on when the button is on, although obviously it would have no way of knowing whether you had manually engaged or disengaged the hub.
Anyone who’s already done the conversion want to give it a try?
If it works, there might be a more elegant solution, like intercepting those wires near the ECU and putting the resister under the dash where it is more hidden and protected.
Anyone who’s already done the conversion want to give it a try?
If it works, there might be a more elegant solution, like intercepting those wires near the ECU and putting the resister under the dash where it is more hidden and protected.
