Like in your opinion do you think we will be replacing a part of the fuse box, or the wire from the fuse box to the connection, or something else? I haven’t had many (if any) issues with the steps up to this point, but also don’t want to sign up for taking apart the entire of the vehicle.
I think you can fix the issue without having to purchase anymore parts. It is just a bad wire connection. Hopefully you can get to the other side of that fuse module that has the wire connections to it. Usually you can unclip things in order to get access to the other side.
A picture of the fuse module while it is installed in the vehicle might help me see how things are put together so I can advise on how to proceed in getting to the other side of it. I haven’t worked on a Lexus before.
Good news and bad news guys. I have lead you astray, as I mentioned in an earlier post, I replaced the fusible link last week (with a new OEM part). This morning when I was disassembling the fuse assembly I removed the fusible link and noticed a break in the 50A heater fuse. So I called Lexus and ordered another fusible link to arrive Tuesday.
See the picture of the blown fuse attached. It was not visible through the windows (like the first one was), and I only noticed upon removal.
My question for you guys is any idea why this link/fuse would blow twice? (The first time I understand from the bad jump, but the second I just don’t get).
Here is the steps I use when I remove and install the fuse module. First, I disconnect the power from the battery. Then, I remove the brake fluid reservoir and platform for it, this allows for access to remove the plastic cover around the fuse box and over the relays. Then, remove the bolt on the stud holding the fusible link in place. Once the bolt is removed the plastic corner cover can be removed and the fusible link can be pulled out. Slide in the new part and perform the steps in reverse. Once the battery connected and components are all back in place. Then, the car is started using the push button and fan turned on. Thoughts? Thanks for your help!!!
Well good find. You now have two possibilities for the trouble. There is either a short in the wiring to the blower or the blower itself has a problem. I think you previously tested the blower by applying power directly to it. If so the blower could be drawing excessive current and still work. I assume the blower motor isn’t getting jammed somehow and can run freely. A jammed motor will draw excessive current. To see if there is a short in the wiring you can use your test light probe by clipping on the positive power point that provides power to the fuse module. Place the probe tip on the contact for that fuse position that the fuse module plugs into. You should see the light turn on. Next, disconnect the blower wiring and then do another probe check. If there is a problem with the wiring the light will go ON again and you will need to track down the short in the wiring. If the light doesn’t turn on then it appears the blower motor is causing the issue. I don’t know the design of the blower assembly but I suspect there is a speed control circuit inside it and that is what is causing the problem.
Don’t install a new fuse assembly until you repair the shorted circuit. If you unplug connector AF4 and the short is still there, I suspect the the fuse box was damaged when the vehicle was jump started. There are circuit tracks inside the fuse box, something may have melted and shorted together.
Great information, but I am confused with both of the tests you guys outlined…
@Cougar: yes, when I previously tested the motor I just applied power, so it could potentially be drawing excess circuit. You are suggesting installing the new fuse module (when it arrives) and while the car is off, testing the power at the post on the fuse module, testing the power at AF4, and then testing the power at the blower motor to see if there is any short in the line. If there is not a short in the line then replacing the motor blower. Is this correct?
@Nevada_545 : I suspect you are correct, that seems more likely to me that short being further down the line, although it would be much easier if it was the blower motor. You are suggesting with the blown fuse assembly installed in the vehicle, unplug connector AF4 next to the parking brake and seeing if the female end of the connector still is not receiving power? Wouldn’t this just eliminate that the short is not in the AF4 connector itself?
You need to test the circuit for a short to ground before installing the new fuse.
You can test the circuit with a test light as Cougar described or you can use your ohm meter. With the ignition off the connector that the fuse plugs into should be an open circuit.
If you unplug connector AF4 it eliminates the blower motor and the wire between the blower motor and connector AF4 from the circuit.
Do not install the new fuse until you have found out what is causing the high current flow issue and fixed it. Is it the blower or is it with the wiring? It is more likely that the problem is with the blower than a wire short issue, unless something has cut into the wiring somehow.
My previous testing advice explains how to use your test light to search for grounding issues. When the clip wire of the test probe is tied to the HOT side of power (positive) and the probe tip touches a ground point, the light turns on, just like it would when you tie the clip lead to ground and touch the probe tip to the hot side of the power source. When you tie the clip lead to the HOT side, the lamp of the probe acts as a load when the probe tip touches a ground, so current is limited to only what can flow through the light. To do that test the fuse module needs to be removed and the probe tip needs to touch the contact point where the fuse would normally plug into. The light should turn on if the short is still on the line. You can then disconnect the blower and see if the light goes out. If it does turn off then you have eliminated the shorting issue. When using the light to find grounds make sure the probe tip doesn’t touch anything else except the contact you are testing. If it contacts other grounds the testing will be invalid.
Thanks for your responses, your help has been invaluable.
I ordered the new part and it should arrive on Tuesday. The tests you outlined make sense, and I will definitely test for a short (and identify the location) before installing the new part. I will keep you both posted. Thanks again!!
You’re welcome for the help. I suspect a new blower module will solve the issue and proper testing will prove if that is true or not.
Ok, so before replacing the fuse I followed both of your directions and determined the high current flow was caused by the blower motor. I replaced the fusible link and the blower motor and SUCCESS! the fan is blowing and on this hot summer day I could not be more thankful for you twos information and experience.
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Good to hear you had success. Good job. You hung in there and solved the problem. It is kind of funny that this issue happened the way it did. I can only think that there is a solid state circuit inside the blower module and voltage spikes on the power bus caused damage to the circuit. You’re welcome for the help on this issue and thanks for the progress update.