HVAC problem/bad wiring

2004 TOYOTA SEQUOIA

185,000 MILES • 4.7L • V8 • 4WD • AUTOMATIC

TIM JEWETT

MEMBER
5 POSTS
FOLLOW

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?

Images (Click to enlarge)

Jan 10, 2017 at 2:54 PM

STRAILER

CERTIFIED EXPERT
53,855 POSTS

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

Images (Click to enlarge)

Jan 14, 2017 at 11:43 PM

TIM JEWETT

MEMBER
5 POSTS

Thanks so much. I haven't had a chance to look at it in depth, but I know this will be very helpful!

Jan 17, 2017 at 8:58 AM

STRAILER

CERTIFIED EXPERT
53,855 POSTS

Good to hear, please get back to us on this problem so we can get it resolved.

Best, Ken

Jan 17, 2017 at 12:12 PM

BELTFED

MEMBER
7 POSTS

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?

Jul 10, 2017 at 11:41 AM

STRAILER

CERTIFIED EXPERT
53,855 POSTS

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

Images (Click to enlarge)

Jul 11, 2017 at 12:10 PM

BELTFED

MEMBER
7 POSTS

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.

Jul 12, 2017 at 4:59 AM

TIM JEWETT

MEMBER
5 POSTS

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!

Jul 12, 2017 at 5:04 AM

BELTFED

MEMBER
7 POSTS

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!

Jul 12, 2017 at 6:11 AM