HVAC problem/bad wiring

Tiny
TIM JEWETT
  • MEMBER
  • 2004 TOYOTA SEQUOIA
  • 4.7L
  • V8
  • 4WD
  • AUTOMATIC
  • 185,000 MILES
I recently bought this truck with various issues. The engine temperature gauge did not work (replaced sensor and still did not work). The sunroof is stuck open slightly, but motor works. And most frustrating was we had no AC/heat controls. The other controls on the HVAC control worked (hazards, 4x4, clock, etc) but not the HVAC and the lights did not light up (circled in first picture). I bought a used one on eBay thinking that would solve it and it also did not work. In my frustration I began unplugging the "new" panel and after removing one of the plugs (circled in the second picture) the lights on the panel came on and we had control of the HVAC. Also, as a result the temperature gauge works, and the outside temperature sensor also works. My thoughts are a loose ground. Any help/thoughts?
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Tuesday, January 10th, 2017 AT 2:54 PM

8 Replies

Tiny
KEN
  • ADMIN
Hey Tim,

There is a few relays and fuses you need to check you. If they check okay here is a wiring diagram (below) and a few guides that will help you get the problem fixed.

https://www.2carpros.com/articles/how-to-check-wiring

and

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

and

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

There are only three diagrams but a cut them in half so you can read them

Please run some tests and get back to us so we can continue helping you.

Best, Ken
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Saturday, January 14th, 2017 AT 11:43 PM
Tiny
TIM JEWETT
  • MEMBER
Thanks so much. I haven't had a chance to look at it in depth, but I know this will be very helpful!
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Tuesday, January 17th, 2017 AT 8:58 AM
Tiny
KEN
  • ADMIN
Good to hear, please get back to us on this problem so we can get it resolved.

Best, Ken
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Tuesday, January 17th, 2017 AT 12:12 PM
Tiny
BELTFED
  • MEMBER
Have the same issue now. No power to AC panel except clock and emergency flasher. Also have the temp gauge out as well. Did anyone figure this one out?
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Monday, July 10th, 2017 AT 11:41 AM
Tiny
KEN
  • ADMIN
Hello,

This gentleman never got back to us so we will need to pick it up where he left off. There are a couple of relays and fuses that need to be checked so we can continue.

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

and

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

Check the wiring diagrams in the post above and the locations (below)

Please run some tests and get back to us we are interested to see what it is.

Cheers, Ken
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Tuesday, July 11th, 2017 AT 12:10 PM
Tiny
BELTFED
  • MEMBER
First, thank you for the reply. I checked the fuses last evening and all appeared to have power except 3. They are H-LP-LH, H-LP-RH (Test light was very dim) and DEF I/UP. Just like the prior 2 posters, the LCD display is blank and no power to AC controls. Clock and emergency flashers work and it is a 2 wheel drive. Also, the temp gauge went out at the same time just like above. Coincidence? I was reviewing the drawings above and see that the coolant temp sensor goes to the ECM. Would that also affect the AC? I checked the coolant temp sensor and it appears OK.
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Wednesday, July 12th, 2017 AT 4:59 AM
Tiny
TIM JEWETT
  • MEMBER
Thanks all for your help on my original question. It appears my issue had to do with the AC module itself, like the ECM but just for HVAC. Finally took it to a shop and they replaced that as well as the coil which had a leak. Thanks all for your help!
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Wednesday, July 12th, 2017 AT 5:04 AM
Tiny
BELTFED
  • MEMBER
Tim, thank you fro the reply. Tim, first is the AC module the long white plastic module on the back of the vent face plate? Is this also referred to as the Integration Control & Panel? When you changed this, did it also correct the coolant temp gauge? Thank you!
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Wednesday, July 12th, 2017 AT 6:11 AM

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