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Skyvisions
Skyvisions, ASE Certified Technician
Category: Toyota
Satisfied Customers: 14422
Experience:  Toyota Master Diagnostic
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Problems with my back door lock on my 2010 fj cruiser. The

Customer Question

Problems with my back door lock on my 2010 fj cruiser. The lock only works when the key is in the ignition and is in acc or on position, and operated with the inside lock/unlock switch. It will not function to lock or unlock with the fob, inside switches, or any of the door key cylinders, with the key out of the ignition. I have replaced the back door lock mechanism and actuator, the key cylinder and wiring, and the back door ecu. Also of note, the rear window will not release even after all of the replacements.
Submitted: 1 year ago.
Category: Toyota
Expert:  Skyvisions replied 1 year ago.

Do you have any wiring diagram, voltmeter and a reasonable knowledge of how to use it? Or the parts that you replaced all new parts or where the used? Was there anything done Recently leading up to this current problem that might help me understand what's going on?

Customer: replied 1 year ago.
I bought it used. At first I could not get the door to lock or unlock at all. After I replaced the parts with new, I noted that it started to work as I described while the key is in the ignition at the acc or on position. The rear window never released. Yes I have access to a wiring diagram from the fj forum and I have a voltmeter. I am by no means an expert but can follow directions. The vehicle must have been offroaded hard as it had red dirt dust inside everything. The frame has it caked in it. Other thought is it may have been under water although I have nothing to prove that. Everything else electrical works well.
Expert:  Skyvisions replied 1 year ago.

Let me look at the wiring diagram when I get into my office I will get some test together for you to check. Probably won't be till early afternoon.

Expert:  Skyvisions replied 1 year ago.

The first thing I need You to do is confirm that you have 12 V to the 10 amp ECU-B fuse and the 20 amp DRL/LCK fuse in the fuse box under the hood? Next I need you to locate the back door ECU which you've already replace there are two connectors in connector A pin number five is a white wire with a red tracer is there 12 V to this wire? This would be with the key off and out of the ignition. The pins are identified by removing the connector with the lock tab at the 12 o'clock position and the face of the connector looking at you pin number one is the top left and the pins are counted up in sequence to the right then the next row. Let me know if these two fuses are blown and if you have 12 V and to the white wire with a red tracer at the body ECU.

Customer: replied 1 year ago.
Ok. Im at work now will check when I get home. Thanks.
Expert:  Skyvisions replied 1 year ago.

OK

Customer: replied 1 year ago.
Ok I have 12 v at tge 10 A ecu fuse. No voltage at the 20 A door/lck fuse. And no voltage at the door ecu pin 5 wht wire with red tracer. All fuses are good.
Expert:  Skyvisions replied 1 year ago.

Just to clarify you're getting no voltage to that 20 amp door lock fuse and you're 100% certain you are on the correct fuse? If you remove the fuse do either of the female pins in the junction block/fuse block have 12 volts?

Customer: replied 1 year ago.
on the correct fuse. No current on either side of the 20 A fuse. And none at the rear door ecu white wite with red tracer.
Expert:  Skyvisions replied 1 year ago.

This is a very complicated situation. If you have 12 V at the 10 amp ECU fuse and you are on the correct fuse yet have no power to the door control ECU in the back door there is either a malfunction in the body ECU pin connections or a problem in the wiring. That is the power supply that feeds the body ECU And the back door ECU when the key is in the off position. Not having 12 V to the 20 amp doorlock fuse even the female pins in the box indicates a problem within the box. That power supply comes directly from the battery into the bottom and into a busbar that feeds multiple fuses in that box. It would be extremely unlikely to see a problem inside the box a less corrosion or water got in there because they were four wheeling. I'm going to submit an offer for a premium service which allows us direct contact via telephone. This comes as an additional cost but may be easier to get this resolved versus trying to go back and forth with my schedule and your schedule. I'm about finished for the evening myself. You can accept this offer at any time if you would like. Having the freedom to discuss this over the phone and exchange information via email will probably be quicker.

Expert:  Skyvisions replied 1 year ago.

Click this link and download the illustration. It will time out. Do any of these fuses in that same block have power to them?

Customer: replied 1 year ago.
Late here tonight. Will check tomm and get back to you. Thinking about premium offer just concerned on when we would find common time when I can be in front of my truck with our schedules.
Expert:  Skyvisions replied 1 year ago.

Click this link and this link and save the illustrations. They will time out. Locate the connector as seen highlighted in yellow. This is just inside the left quarter panel where the harness comes through the boot from the door. Locate pin number 10 disconnect the connector is or any corrosion that connector. Locate pin number 10 does the white wire with the red tracer Which is the same wire that goes to the back door ECU that has no power. Is there any corrosion in this connector and does the white wire with a red tracer at pin number 10 have 12 V to it? I will be available most evenings especially tomorrow and Friday I have not much planned and would be available to walk through things on and off during the course of the evening. I am on East Coast time.

Expert:  Skyvisions replied 1 year ago.

Have a good evening. Remember that my information is only as good as your ability to follow the steps and test everything appropriately. Doesn't take a rocket scientist just make sure you have good grounds on the black lead of your voltmeter and your probing and checking the right pins and voltages as I am asking. Otherwise we will end up on wild goose chases and get nothing accomplished.

Customer: replied 1 year ago.
Ok I saved the diagrams. Will carefully check it all tomm and get back to you. I am east coast as well but early work. Out at 0600. Thanks for your help.
Expert:  Skyvisions replied 1 year ago.

OK

Customer: replied 1 year ago.
Ok so first off I was worng about the 20A dr/lok fuse. There is 12 volts at the fuse on the side to the front of the truck.
I found the plug connector you highlighted in yellow and confirmed 12 v at tge white/red wite in pin 10. Unfortunately the side of the connector that is from the tail gate the white/red wire has pullrd out of the connector and I can't figure out how to re attach it. This is proba ly the problem? Or at least hindering any further diagnostics?
Customer: replied 1 year ago.
After much tadoo I bypassed the connector on the White/red wire and now have 12 v at the door ecu pin 5.
There was a crap load of red dirt in the left quarter panel and in and on the connector. I cleaned it up and do not see any corrosion.
Unfortunately I am now back to the back door lock not working at all, even with the key on when it worked before.
Calling it wuits tonight.
Expert:  Skyvisions replied 1 year ago.

There has to be something going on in that harness going up to the back door ECU. That white wire with a red tracer is the constant 12 V power supply that makes the back door ECU work on the system. There are multiple things you have to take place but the power supply is the most important. That explains why it only seems to want to work with the key in the on position. That system has to be active continuously that's why they power supply comes directly from the battery through those two fuses I listed then powers of the body ECU and the back door ECU. Let me know how things go.

Customer: replied 1 year ago.
I am thinking It may be easier to replace that wiring harness? After bypassing the white/ red wire I have 12v at the door ecu. But now the lock does not work at all even with the key on. The rear window still is inoperative and now the rear wiper does not work as of this am.
Frustrating.
Expert:  Skyvisions replied 1 year ago.

If that pin pulled out of the connector it's possible there is damage to that connector and by disconnecting it you may have aggravated something else look very carefully at those pins in the connector make sure there's no corrosion then I would probably pull the harness out of the door and strip it down and inspect it. There had to be reason why the wire was pulled out for the wire was damaged. Getting 12 V to the back door ECU is critical but there are other multiple things that have to be in place for the system to work. This includes getting to the body ECU and checking things further.

Customer: replied 1 year ago.
Ok will do. Thx.
Expert:  Skyvisions replied 1 year ago.

You are welcome.

Customer: replied 1 year ago.
I'm checking on getting another wiring harness with a new multipin plug. I'll let you know. Thx for all your help so far.
Expert:  Skyvisions replied 1 year ago.

You are welcome.