Now what?

[zonianbrat]

Ok so I posted a thread a while back about my rear hatch not opening. Nothing works on the rear hatch. I have power after testing with a voltmeter. Checked all fuses 4 effin times. found a wire with corrosion and fixed it. Finally bought another ecm. And I still have nothing. I'm so tired of searching so dont tell me to as I have read every thread there is about this issue. Really thinking about heading to the dealership and trading this thing off at this point.

I probably wont but I am just really really pissed and tired of this thing having so many issues.

Anybody got any ideas on what to do next?

 

[NJshadow93]

Possibly a mechanical issue? Maybe the hook is seized up somehow?

 

[m@x]

Ok so I posted a thread a while back about my rear hatch not opening. Nothing works on the rear hatch. I have power after testing with a voltmeter. Checked all fuses 4 effin times. found a wire with corrosion and fixed it. Finally bought another ecm. And I still have nothing. I'm so tired of searching so dont tell me to as I have read every thread there is about this issue. Really thinking about heading to the dealership and trading this thing off at this point.

I probably wont but I am just really really pissed and tired of this thing having so many issues.

Anybody got any ideas on what to do next?

Can you post the link to your other threads regarding the issue? Just wanted to read through it before throwing ideas.

Thx
Max

 

[zonianbrat]

Possibly a mechanical issue? Maybe the hook is seized up somehow?

I can still open the door manually from the inside yet the window, rear defroster and wiper will not do anything.:ybrick:

 

[NJshadow93]

I can still open the door manually from the inside yet the window, rear defroster and wiper will not do anything.:ybrick:

Can you still use the window with the key in the rear hatch?

 

[m@x]

Ok so I posted a thread a while back about my rear hatch not opening. Nothing works on the rear hatch. I have power after testing with a voltmeter. Checked all fuses 4 effin times. found a wire with corrosion and fixed it. Finally bought another ecm. And I still have nothing. I'm so tired of searching so dont tell me to as I have read every thread there is about this issue. Really thinking about heading to the dealership and trading this thing off at this point.

I probably wont but I am just really really pissed and tired of this thing having so many issues.

Anybody got any ideas on what to do next?

zonianbrat,
can you put the reference to the previous thread where you've already gone through certain steps?

If nothing works in the back then I assume there could be only one wire delivering the voltage for all the electrical components in the back. Could that wire be dead? On which end did you check the power with the voltmeter?
Did you try to find what connectors are in the door?
Does your rear window heater work?
Wipers? Water pump? Stop lamp (on the spoiler)?

 

[zonianbrat]

Can you still use the window with the key in the rear hatch?

Negative. It doesnt do anything. When I try to open the window with the key fob I get a single beep like when you lock the doors but nothing actually happens.

 

[zonianbrat]

zonianbrat,
can you put the reference to the previous thread where you've already gone through certain steps?

If nothing works in the back then I assume there could be only one wire delivering the voltage for all the electrical components in the back. Could that wire be dead? On which end did you check the power with the voltmeter?
Did you try to find what connectors are in the door?
Does your rear window heater work?
Wipers? Water pump? Stop lamp (on the spoiler)?

I will try to find the previous thread to reference but I am super busy today and shouldnt even be on the cpu now.:lol:

My friend is an electrician at work and he tested the wires with the meter. I was tending to one of my kids while he worked so maybe he missed something. We did a search on google before hand and found a thread with email conversation with a tech who told the person step by step which wires to test. We printed that out and that is what my friend went off of. He said everything tested fine. Hot wires were hot and the ground was good too. He checked the wires in the back hatch since I have the back panel off. FYI rear window heater does not work nor does the rear wiper or the rear window wash pump. The 3rd brakelight does work. This is crappy as I am moving a bunch of stuff with the trailer but could make half as many trips if I had the rear of the 4r.:toilet:

 

[NJshadow93]

Maybe the window motor is shot. I have heard that if the window isn't fully closed, even though it may appear to be, the wiper and defroster won't work since its all connected. Just a thought.

 

[BlackWorksInc]

Zonianbrat, checking powers and grounds is a good start. Did you happen to check input/outputs of the module? You would do this by measuring voltage changes when activating the switch, manipulating sensors, jumping wires for inputs that indicate "closed" and so on. I can get into more detail if you want, but you're going to need at least a DVOM, some spre jumper wires, a bit of time. Preferably I would recommend also using a power probe as well and a low amp probe if you have one.

 

[zonianbrat]

Zonianbrat, checking powers and grounds is a good start. Did you happen to check input/outputs of the module? You would do this by measuring voltage changes when activating the switch, manipulating sensors, jumping wires for inputs that indicate "closed" and so on. I can get into more detail if you want, but you're going to need at least a DVOM, some spre jumper wires, a bit of time. Preferably I would recommend also using a power probe as well and a low amp probe if you have one.

Nor my friend or I checked inputs of the module. I'm assuming you mean the module in the rear hatch? If so I have two of them (I bought a used one). Neither one of them help out the situation. We didnt check for voltage changes either. Please let me know what we should do in detail cause I am at the end of my rope with this thing and I know if I take it to a shop i'll end up spending hundreds of dollars in labor.

 

[BlackWorksInc]

So to make things a little more complicated for you, that rear door ECU is very heavily dependent on network communication. Even though the rear window switch, door latch, and such goes directly into the Rear Door ECU; the majority of inputs such as Window Lock-out, Lock/Unlock, ect are given via the Multiplex communication line. Also the fact you swapped out the ECU for a used one and still had no response along with the loss of functionaility in all functions associated with the Rear Door ECU makes me think it might be a network issue, which will require a scantool capable of communicating with all availible modules on the vehicle (your standard code reader and/or lower end scantools will not be able to do this.)

So this complicates diagnostics and may put this out of your capability to continue testing effectively. I need to look over the diagrams and try and figure out how to approach this with a limited toolset, because at this point I would use the TIS Techstream, DVOM, Power Probe, and a DSO to do my diagnostics; which you don't have access to I assume.

(Edited)
Something you can do in the meantime is to check the connection between the Body ECU and the Rear Door ECU. At Connector B4 (Connector A to Body ECU) Pin 23 there should be a Brown w/ Red Stripe Wire, this is the Multiplex communication line from the Body ECU to the Rear Door ECU. At the Rear Door ECu this will translate to a Red Wire at Pin 1 Connector B8 (Connector A to Rear Door ECU.) At this point just look for connectivity, a break or damage to this wire can result in a loss of communication. It won't set an MIL because its a body control and has no real bearing on Emmisions which is what causes a DTC to set the MIL.

 

[BlackWorksInc]

Something of interest I came accross... I can't find anything that dictates where the window is. What I mean by that, is there is no sensor or switch that detects that the window is not at full rest or fully open, which is confusing because I can't tell HOW the Rear Door ECU determines the window glass being open or closed to prevent the rear wiper from working...

I assume there's a learned value or some sort of small hall effect sensor in the motor itself (it has about 4-5 wires going to it.) But this would not affect the rear hatch door opening/closing. So I'm still a bit stumped here as to what is killing the rear door... Does the 3rd Brake light work also?

 

[m@x]

BlackWorksInc has extensive knowledge on this topic.

It looks like you either:
1) have a bad control unit in the back - we excluded this by replacing one.
or
2) a common line is shot. In general lines I assumed there was a hot wire feeding all the devices and then at least 1 control wire per device + ground. But BlackWorksInc pointed out that there was a smarter communication with the rear door. The data link could very well be the culprit.
3) The data uplink on the main brain is not talking to the rear. Could a logic probe be useful in this case?

I don't know much about this, but this is what my troubleshooting common sense tells me.

If I don't make sense, shut me up. eep:

 

[BlackWorksInc]

BlackWorksInc has extensive knowledge on this topic.

It looks like you either:
1) have a bad control unit in the back - we excluded this by replacing one.
or
2) a common line is shot. In general lines I assumed there was a hot wire feeding all the devices and then at least 1 control wire per device + ground. But BlackWorksInc pointed out that there was a smarter communication with the rear door. The data link could very well be the culprit.
3) The data uplink on the main brain is not talking to the rear. Could a logic probe be useful in this case?

I don't know much about this, but this is what my troubleshooting common sense tells me.

If I don't make sense, shut me up. eep:

You're making sense, I believe in '05 and up we went to a straight CAN Bus system (I don't remember exactly, Toyota likes to call some of their Can Stuff Multiplex still, sort of how TRAC became ATRAC but still is the same thing...) CAN uses a twisted pair of communication lines (much like a pair from the CAT-5 or 6 line that is supplying your internet,) This data communication line seems to be a single wire, unfortunately Toyota does not really provide how the waveform will look on a lot of their datalines in general.

For example, using a logic probe (like a Power Probe III or something similar) would maybe let you know there is voltage on the line. The problem is you don't know if that's good or bad. If the system grounds the dataline for communication then constant voltage might be good or it could be bad.

What I mean by that is if you hooked up a DSO (Digital Storage Oscilloscope) to the data line, you'd get most likely a funky looking square wave or some sort of pulsed transmission. But trying to decode that transmission is fairly difficult, so you could be looking at the BCM sending A signal to the Rear Door ECU, but it may not be a CORRECT signal if that makes sense; since information like using the switch at the Driver's seat, unlocked/locked doors, and Key Fob data is provided by the BCM over the communication line.

At the very least, establishing that there is connectivity on the line from the BCM to the Rear Door ECU lets us know that dataline is still connected.

 

[zonianbrat]

So to make things a little more complicated for you, that rear door ECU is very heavily dependent on network communication. Even though the rear window switch, door latch, and such goes directly into the Rear Door ECU; the majority of inputs such as Window Lock-out, Lock/Unlock, ect are given via the Multiplex communication line. Also the fact you swapped out the ECU for a used one and still had no response along with the loss of functionaility in all functions associated with the Rear Door ECU makes me think it might be a network issue, which will require a scantool capable of communicating with all availible modules on the vehicle (your standard code reader and/or lower end scantools will not be able to do this.)

So this complicates diagnostics and may put this out of your capability to continue testing effectively. I need to look over the diagrams and try and figure out how to approach this with a limited toolset, because at this point I would use the TIS Techstream, DVOM, Power Probe, and a DSO to do my diagnostics; which you don't have access to I assume.

(Edited)
Something you can do in the meantime is to check the connection between the Body ECU and the Rear Door ECU. At Connector B4 (Connector A to Body ECU) Pin 23 there should be a Brown w/ Red Stripe Wire, this is the Multiplex communication line from the Body ECU to the Rear Door ECU. At the Rear Door ECu this will translate to a Red Wire at Pin 1 Connector B8 (Connector A to Rear Door ECU.) At this point just look for connectivity, a break or damage to this wire can result in a loss of communication. It won't set an MIL because its a body control and has no real bearing on Emmisions which is what causes a DTC to set the MIL.

Ok....sounds like french since I am so tired but I am willing to give this a try possibly tomorrow. Do you by chance have a diaghram? I'll have to see if my buddy can bring over his voltmeter too. Any idea exactly which fuses feed the back? My buddy and I checked all the fuses but if I knew which ones actually fed it I would just replace all of them just to eliminate and cover all of my bases. Oh and the 3rd brake light does work.

Bri

 

[MikeInNH]

unfortunately Toyota does not really provide how the waveform will look on a lot of their datalines in general

This sounds like a digital signal...NOT an analog signal. So there is no waveform pattern. It'll be different for each and every combination of signal.

Multiplex line is just a line that is sending multiple signals to multiple devices over the same line. This isn't complicated or new or all that creative. It just saves labor and material when building the vehicle. The problem with it ...is it's a single point of failure. So if the line goes bad..then multiple devices won't work. Hard to troubleshoot.

 

[zonianbrat]

Gotcha!

 

[BlackWorksInc]

This sounds like a digital signal...NOT an analog signal. So there is no waveform pattern. It'll be different for each and every combination of signal.

Multiplex line is just a line that is sending multiple signals to multiple devices over the same line. This isn't complicated or new or all that creative. It just saves labor and material when building the vehicle. The problem with it ...is it's a single point of failure. So if the line goes bad..then multiple devices won't work. Hard to troubleshoot.

You're right it is a digital signal, any while it will vary its still a limited amount of information so the signal should stay the same according to the action. i.e. pressing up on the console with the doors unlocked, and the vehicle idling should result in the same digital information each time.

But you will see a waveform. I've done this checking communication lines, the issue is just a matter of decoding that signal.

 

[m@x]

This sounds like a digital signal...NOT an analog signal. So there is no waveform pattern. It'll be different for each and every combination of signal.

Multiplex line is just a line that is sending multiple signals to multiple devices over the same line. This isn't complicated or new or all that creative. It just saves labor and material when building the vehicle. The problem with it ...is it's a single point of failure. So if the line goes bad..then multiple devices won't work. Hard to troubleshoot.

Even though the signal is digital and represented by 1's and 0's, the voltage in the wire still has an analog waveform since there are raising and falling edges between the high and low levels that represent those 1's and 0's.