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Discussion Starter · #1 ·
I wanted to do this mod pretty badly since I love having the automatic a/c controls on my Touring Odyssey and wanted them in my Tundra. Reading through this thread

http://www.tundrasolutions.com/forums/tundra/134593-change-manual-c-heater-auto-digital/

to do this mod is a little sketchy because there are just bits and pieces of information here and there. I thought I'd post a complete DIY picture tutorial of how I did this mod. First here are the parts that you will need:

1. Heater A/C control -Crewmax, Limited Dual Zone (sorry I don't have the part number but you probably don't want to buy it new because it costs a fortune)





I did my part search here: Car-Part.com--Used Auto Parts Market
This is a little tricky part to get because if you're not careful you will end up ordering a manual panel or even a Sequoia panel. One hint is to go to TruckTrader.com and look up a Limited Tundra, check out the pictures of one that has the digital panel and use that VIN to do your part search. When you get your results make sure you call the salvage yard and ask them to do a sight verification that it is indeed a digital panel. I even asked them to see if my panel still had the heated seat switches (next mod) in them which it did. Mine was $295.00.

2. A/C Amplifier -PN 88650-0C070
AMPLIFIER ASSY, AIR



I ordered mine here: Conicelli Parts Center

Mine was $337.19

3. aspirator pipe - PN 88897-12210








This 'Venturi tube' may be the most difficult part to find. I ordered mine locally here at a Toyota dealership and the parts girl said it was the only one left in the country. I guess I got lucky. My cost was about $35.00

4. Thermistor, cooler -PN 88625-47021

I ordered mine here: Conicelli Parts Center



This part costs $19.01

5. Hose, air -PN 88669-0C030



I ordered mine here: Conicelli Parts Center

This part costs $9.11

Next you'll want to swap out the panel. Here is a sweet picture tutorial for those of you who have the center console:
How to Install Stereo 2007 2008 Toyota Tundra

For those who do not have the center console use the directions here in the attached pdf:

http://www.tundrasolutions.com/forums/audio-and-stereo/132775-removing-dash-for-headunit-install/

Once you plug in your digital a/c panel leave the bottom section of your dash apart so you can install the aspirator pipe and air tube if you want. More on this later...

Next is swapping out the a/c amp. You will gain access by removing the lower glove box:

http://www.tundrasolutions.com/forums/interior-and-exterior/154110-08-glove-box-removal/

Once the glove box is removed on the left side you will see a tube coming down from the center dash. Use a crossed tip screwdriver to remove the one screw holding that in. Now unscrew the two screws holding in the A/C amp aka ECU.







When you unplug the original ECU connections you will be working with J19. Leave Z1 aside.



Look for J19-29 and J19-34. If you already have wires there then you can skip the next step. You should be already wired for the Thermistor and it may be tucked away on the right side of the kick panel below the steering wheel.

"Fold and stuff" an 18 gauge solid wire into these pins as demonstrated by Popo2239 in this awesome thread:

http://www.tundrasolutions.com/forums/tundra/192965-official-how-add-mpg-buttons-thread/

J19-34 needs to be run to chassis ground and then to one pin of the two pins of the thermistor. J19-29 can be run straight to the other pin of the thermistor.






At this point you can plug in your J19 and Z1 into your new ac amp and replace it where your old amp was.

You will need to somehow solder or add female ends to your newly pinned wires to connect to the back of two pins of the thermistor. I happened to find an unused 2 pin connector here:



I clipped this unused one off and attached my J19-34 and J19-29 to this. You will have to modify this connector slightly in order it to fit into the back of the thermistor. Using a box cutter or sharp knife to cut off the one side of connector that is preventing it from sliding onto the thermistor. You will see what I'm talking about when you try to plug it into the thermistor.




The thermistor attaches to the back side of the kick panel below the steering wheel.


Unscrew the two 10mm bolts holding the kick panel in and pull away from the dash and it will come loose. Run your two wires behind here to connect to the thermistor with the two pin connector. After you connect your wires leave this panel open for now so that you can run your air hose to it.

Next you will need to remove the ash tray and cup holder to gain access to the area behind it. The arrow points to the section you will need to cut out to be able to install your venturi tube.


I used a multifunction tool with this attachment to cut away the section. I'm sure a regular dremel tool would work also.


this picture shows how much needs to be cut away and where the venturi tube will click into:


Now use a 7/8 drill bit, hole saw or dremel to carefully and gingerly cut out only the center portion of the area:


attach your air hose to the venturi tube (aspirator pipe) and click into the hole you just made. I put some silicone around the tube to get a better seal but I don't think it is absolutely necessary.


Now connect your air hose to the thermistor and click in your thermistor to the back of the kick panel and replace the kick panel, cup holders, glove box and ash tray to complete and enjoy your mod.





Okay here's were some extra info I discovered when I was doing my conversion.
If you do not change the AC amp(ECU) you will not have control over your fan speeds so you definitely need this part.

In my experience you can operate this in a manual-type mode.

If you only install the digital panel and AC amp you will be able to operate your panel as a manual panel. You will not be able to dial up certain temperatures. It will only blow heated air or cold air. Hot air only will blow out on any selected temperature between 75 degrees and Hi. This will be your heater mode. If you select LO on the dial the air conditioned, cold air will blow and this will be your A/C mode. In these two modes you will be able to control how much air is blown into the cabin to regulate your desired temperature.

Another observation is that if you do not hook up the venturi tube but do wire in your thermistor your system will operate close to normal and you will be able to dial up temperatures but there will be some lag in what you dial and what you actually feel. This is because in my understanding the venturi tube and hose is used as a vacuum to draw air over the thermistor from the cabin to help tell the ECU how much heat or cold to add to the cabin to regulate the temperature. If no air is actively being drawn over the thermistor there will be some lag in dialed temperature and actual cabin temperature.

If you decide to do this mod and absolutely cannot source a venturi tube, I could be wrong, but I do not think you will be able to fabricate one to properly create the vortex/vacuum to pull air when connected to the heater box. The solution to this is to do either one of these methods:

1. Install your thermistor and wire it up but also mount a small computer-type CPU fan behind the thermistor to pull air from the cabin over the thermistor.

2. Install your thermistor and wire it up but connect a generic tube from it and run it to the upper portion of the area where your cabin air filter goes.

Here the tube will be able to get the suction needed to pull air over the thermistor.

I'm sure someone can think of other ways to draw cabin air over the thermistor and they are welcome to share with others attempting this conversion.

One last note about the mod is that a few members have noticed that the panel will not remember its last setting after the truck is off for greater than approximately 30 minutes for some reason and defaults to the off position and 75 degrees when you turn it back on. It may not be a concern for most people but may be annoying for those who are in and out of their trucks a lot and have to reset it each time. This also may be a concern for those who have remote start and want to cool down or heat up their truck before entering. I have studied the each harness on the manual and auto ac and cannot seem to determine why it resets each time. Maybe someone can chime in who has figured out the solution to this.

A follow up mod to this would be for those who added the leather Sequoia steering wheel as I did with the audio and A/C CONTROLS. It would be great to be able to tie into the digital panel to have these buttons actually function. I imagine that the key to this would be adding the matching Sequoia digital panel and Sequoia AC amp or running the wires from the steering wheel connector to J37(connector to the back of the Digital AC panel). Any help with this would be appreciated.



Good Luck!
 

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The M.F.I.C.
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Re: Change Manual a/c heater to Auto digital

^^^ eyeckr ^^^ --- That's an excellent writeup. Thanks for posting all that! You should start a new thread as a "How to..." so we can make it a sticky. Thanks for all your work!.

:tu:
 

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Re: Change Manual a/c heater to Auto digital

EYECKR that is an AWESOME write up! KUDOS my friend! I am just getting ready to do this mod and would have been somewhat lost without these directions. You have save me TONS of time, thanks again!
Ken
 

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Re: Change Manual a/c heater to Auto digital

thanks EYECKR for the write up!
 

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Re: Change Manual a/c heater to Auto digital

thanks EYECKR for the write up!

Thank you very much for putting this together. I really hope this DIY makes it to the DIY section.

Its a shame to learn about the reset issue you were talking about. I can see where that would be annoying everytime you get in your truck that you have to change the Temp from 75 back down to something more suitable for say summer or whatever.

I wonder if there's a connection to the battery that it needs established to retain memory of temp settings.
 

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Re: Change Manual a/c heater to Auto digital

Thank you very much for putting this together. I really hope this DIY makes it to the DIY section.

Its a shame to learn about the reset issue you were talking about. I can see where that would be annoying everytime you get in your truck that you have to change the Temp from 75 back down to something more suitable for say summer or whatever.

I wonder if there's a connection to the battery that it needs established to retain memory of temp settings.
That is exactly what I was wondering. Either that, or I wonder if there is a main ECU reprogramming issue that can address the problem. I am getting ready to do this mod and would love to find an answer. I know there are some big brains in this forum that can probably figure it out. Any help would be GREATLY appreciated.
Ken
 

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Discussion Starter · #7 ·
Re: Change Manual a/c heater to Auto digital

You're welcome guys. I'm glad I could offer some help. I had studied the previous posts for what seemed like hours to gather enough of the tidbits of information to gain enough courage to attempt the mod. I currently enjoy the digital control look and functionality but still ponder on the reset conundrum. I am not bothered so much about resetting the temp but would like to solve this issue.

I did run straight battery power to J19-21 with is supposed to be the 'always 11 to 14V' supply to the panel and it did not correct the reset problem. The only two wires not wired in our 'manual system' trucks that are missing in our wiring harness are the ones for the Driver(J19-33) and Passenger(J19-32) solar sensor. Are these solar sensors the key to the problem?? I even looked at connector Z1 and those are wired identically in the Auto and Manual system. All the other wires are there so I'm thinking it is not the wiring harness but still don't have the last piece of the puzzle.

One thing I just thought of is to check the pins on J37 which is the actual connector to the back of the Digital Control Panel. Maybe the J19-21 constant ECU power is somehow not making it to the panel and is not wired in on J37??

Well, I just looked at the J37 layout and from what I gather there are supposed to be essentially three wires going to it, none of which are constant power

J37-16 Ignition power supply
J37-1 Body ground
J37-3 LIN communication

I have the PDF to the layout of the terminals of the Manual system and Automatic system ECU and can PM/email them to anyone who wants a copy to further study the pins.
 

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Re: Change Manual a/c heater to Auto digital

The only two wires not wired in our 'manual system' trucks that are missing in our wiring harness are the ones for the Driver(J19-33) and Passenger(J19-32) solar sensor. Are these solar sensors the key to the problem??
eyckr: There are TWO light sensors? I thought there was only one?
One other thing that has baffled me about this setup (I am easy to baffle) is that there is only one air sample intake to read the air temp. Shouldn't there be two since it is a "dual climate zone" setup?
Thanks,

Ken
 

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The reason I would want to do this mod is to keep the recirc function from automagically changing its setting. With the auto air installed at the factory, you can have this so-called feature turned off.

Since you're installing the auto air amplifier to make this mod work, does it follow that you should be able to change it so that the recirc function is manual only?
 

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Re: Change Manual a/c heater to Auto digital

eyckr: There are TWO light sensors? I thought there was only one?
One other thing that has baffled me about this setup (I am easy to baffle) is that there is only one air sample intake to read the air temp. Shouldn't there be two since it is a "dual climate zone" setup?
Thanks,

Ken
Good question but I suspect even in a dual climate zone only one air intake is required. For example the AC would sample the drivers side calculate the difference for the passenger. I.E. IF passenger wants 80 degrees and the Driver requests his to 75. Sampled Air equals 75. Increase passenger temp +5

Just a theory..
 

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Re: Change Manual a/c heater to Auto digital

Good question but I suspect even in a dual climate zone only one air intake is required. For example the AC would sample the drivers side calculate the difference for the passenger. I.E. IF passenger wants 80 degrees and the Driver requests his to 75. Sampled Air equals 75. Increase passenger temp +5

Just a theory..
That makes sense. What about the light sensor? I only see one in the parts catalog. I puled the plug on my light sensor cover and the wiring is tucked right into the cover. I ordered a light sensor and after I do the mod (could be weeks from now) I will post the results. Maybe the light sensor is the key, so I will take a gamble and give it a try.
BTW I am buying my parts from ToyotaPartSales.com (Toyota of Dallas) on recommendation of some other members. Their prices are good, but they TAG you on shipping. I emailed them to see if they could cut me a break as all the parts together weighed less than a pound, and they were charging me $55 to ship via Fedex Ground! They did end up refunding me $20, so I guess it paid off.
Ken
 

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I just got a 2011 Sequoia SR5. It has the Auto A/C, but no steering wheel A/C control like the one in this picture. Do you think that this A/C control part is a plug-n-play for me?

A follow up mod to this would be for those who added the leather Sequoia steering wheel as I did with the audio and A/C CONTROLS. It would be great to be able to tie into the digital panel to have these buttons actually function. I imagine that the key to this would be adding the matching Sequoia digital panel and Sequoia AC amp or running the wires from the steering wheel connector to J37(connector to the back of the Digital AC panel). Any help with this would be appreciated.



Good Luck!
 

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Discussion Starter · #15 ·
Ken -I'm not sure where the other solar sensor is located or if it really is wired in but the layout of the ECU terminals lists both of them:



This diagram only shows one solar sensor though:


Maybe the light sensor is the key that will complete the circuit that allows the ECU to keep the last setting. Please do post your results whenever you get around to do your conversion. Also nice work on getting your shipping costs reduced.

Dysan911 -I also wondered why there was only one thermistor but your theory about adjusting based on the drivers side sampled temperature makes sense.

Crazy2bealive -if you do take your switches out I'm sure someone will be interested in buying them to do their heated seat mod.

Travinh -I think it's worth a shot. I'm not sure how much the switch costs but I think since you already have the auto HVAC you stand a good chance of a plug & play mod. If not I suspect you will just have to run a couple of wires from the steering wheel connector aka J45 to the digital control panel aka J37.
 

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Ken -I'm not sure where the other solar sensor is located or if it really is wired in but the layout of the ECU terminals lists both of them:



This diagram only shows one solar sensor though:


Maybe the light sensor is the key that will complete the circuit that allows the ECU to keep the last setting. Please do post your results whenever you get around to do your conversion. Also nice work on getting your shipping costs reduced.
our theory about adjusting based on the drivers side sampled temperature makes sense.
That is really wild. I wonder if the ECU is also used for the Sequoia and maybe the Sequoia does have two lights sensors? Just a guess. I cannot imagine where the second sensor is in the Tundra. I have service manuals so will do some research.
Another thought is what if you tied J19-32 & J19-33 together and connected them to the one light sensor (essentially using on light sensor instead of two)?
I am going to try using the one light sensor and see if that solves the reset problem. I have been busy with some other stuff but will try to give it a go this week and will post results.
Thanks again for all the great info.
Ken
 

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I finished this mod this morning. It only took about 2 hrs thanks to the excellent how-to instructions. Making the hole for the venturi was a little tricky because there was no room to drill a hole, so I ended up using a Dremel tool instead.
A couple of things that I wanted to share:
I have a 2008 Crew Max 4WD SR5, and the thermistor wires and plug were already there, so I was saved the hassle of having to tie into the A/C Amplifier Connector.
I DID install the driver side light sensor, and unfortunately my A/C controls do reset after being off for about 30 minutes or so. I would love to find to solution for this. One thing that I did notice was that there was a two pin connector coming from the Z1 connector (either pins 5&6 or 7&8 not sure which). The connector is tucked up by the A/C Amplifier and is unused (see attached photo). I am very curious as to what this connector is used for, maybe the key to the reset issue? I still wonder if tying the wires from J19-32 and J19-14 together with J19-33 and J19-14 to the light sensor would "trick" the A/C Aplifier into thinking there were two light sensors installed.
Other than that the project was very straight forward.
Ken
 

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