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Heating and hazard light and central control panel not working?

Tiny
MARK2345
  • MEMBER
  • 2004 LEXUS RX 400H
  • 4WD
  • AUTOMATIC
  • 110,000 MILES
My central control panel has gone completely dead. No buttons will turn on anything including heating, navigation buttons, air con and the button for the hazard lights does not activate them. The map still comes on the navigation screen but can’t get off that as no buttons work.

Have checked all fuses and seems ok. Radio buttons just below panel all still work.

Any help welcome.

Thanks,

Mark
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Thursday, October 10th, 2024 AT 11:04 AM

9 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 48,363 POSTS
Hi Mark,

The only circuit that I can see that is shared is the ECU-b1 fuse which we need to see if the fuse is good and that it has power.

Here is a guide to help:

https://www.2carpros.com/articles/how-to-check-a-car-fuse

Here is the location of the fuse under the hood fuse panel. Check out the images (below). Please let us know what happens.

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Thursday, October 10th, 2024 AT 3:48 PM
Tiny
MARK2345
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Hi, I have checked the fuse and it looks good. Just before it all stopped working the hazard lights kept switching off and on and then it all went dead. Is there something else I need to check?

Thanks very much for your help.

Mark
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Saturday, October 12th, 2024 AT 2:02 AM
Tiny
KEN L
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Does the ECU-b1 fuse have power on both sides? To confirm the HVAC controls are dead and the hazard lights? Is there anything else that is not working?
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Sunday, October 13th, 2024 AT 9:01 AM
Tiny
MARK2345
  • MEMBER
  • 5 POSTS
Hi Ken,

Sorry for late reply. Yes, both sides of that fuse have power. And yes, all buttons that control the navigation, heating and hazard light switch are dead.

Thanks for your help,

Mark
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Wednesday, October 16th, 2024 AT 11:08 AM
Tiny
KEN L
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  • 48,363 POSTS
Okay, let's do the same check for the ECU-IG-1 fuse in the fuse panel by left side of the dash. Again, test with the ignition power on. Here is he fuse location. Check out the images (below). Please let us know what happens.
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Thursday, October 17th, 2024 AT 8:37 AM
Tiny
MARK2345
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Hi Ken, all checked and that fuse is good. Is there anything else that could be the problem?

Thanks,

Mark
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Thursday, October 17th, 2024 AT 9:16 AM
Tiny
KEN L
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  • 48,363 POSTS
Okay, let check the wht/blk wire at the AC amplifier for ground, this guide will help and I have included the HVAC system wiring diagrams so you can see how the system works and which wires I am talking about, I marked them in red.

https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester

Here is how to remove the AC amplifier as well. This part may be bad, if it has power and ground get a used unit from ebay and try it. Check out the images (below). Please let us know what happens.
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Friday, October 18th, 2024 AT 10:29 AM
Tiny
MARK2345
  • MEMBER
  • 5 POSTS
Hi Ken,

So I’ve had a mechanic look at it and he said I needed to replace climate control system. I have asked him what exactly that is but have not heard back from him. He said to look on eBay and I have bought what’s in the attached photo. Do you think this is what he meant?

Thanks very much,

Mark
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Thursday, November 7th, 2024 AT 7:27 AM
Tiny
KEN L
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I know you checked the fuses but was there power at the fuse with the systems on? I don't think replacing the HVAC controller will fix the problem because there are two other systems that are not working which means a bad power source or ground, this is why I needed you to check the power source.
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Thursday, November 7th, 2024 AT 5:38 PM

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