Heater quit... sort of

[CHRISMC1]

I'm gonna try this, wish me luck

[jenkster1971]

Thanks Wizzer. This is the second time this happened to my 2001 Highlander. Your fix worked great! One item, though. There is a wire band on the circuit board I had to disconnect to get the back off. No big deal. With my fingernail I pulled up on either side of the black base. This unlocks the wire band. Then the band just pulls out. Install is reverse.

[blue50706]

Wizzer and dfluitt : Thank You for the posts and info. My 03 Highlander, same problem, 3 wires broke. My solution required an independent automotive shop to remove unit, etc., took unit to a communication shop for soldering the three new wires, and back to the auto shop for re-assembly and installation. 1.5 hrs at most. Thank goodness for good, accomodating shops and Good People. Many Thanks to all of you! War Eagle!!! for Auburn Football.

Blue

[plbstp44]

HI, i have a same problem with my highlader 02 and after reading your comment i resolved my problem thank you verry much

[Bernstorm]

Just add my voice to the many thanks to Wizzer, defluitt and the other ones who contributed:
Same problem. Same fix. Saved nearly a $1000!!!!!!

P.S. I see that my reply is no. 185 ; Assuming (don't have patience to count) that half of that count are people who made the fix, that's over $90,000 saved by this thread alone. That's the power of knowledge sharing through Internet!

[sailerguy1]

I have a 2005 and the same problem. found the broken wires, but another wire came out and was unable to repair it. however, I found a replacement unit at a local auto yard for $135, or nearly $600 less than a new one. It works great! Thanks to all who provided the help on this, by which I was able to remove the dash and unit and replace it all myself. No labor charges!

[emerald_quay]

Hi. Can anyone tell me if the heat control panel is the same for all model years? I am talking about part number 55904-48210. My highlander is a 2004. Is the heat control unit from an '01 02 03 05 06 all the same? Thank you for your time

[grizzlyowl]

Ok where can I find the thread that has some pictures of the panel removal and soldering of the broken ribbons for the AC knob? Thanks!

[grizzlyowl]

Originally Posted by dfluitt

Hi Wizzer. The Toyota dealership here in Santa Rosa California charged me $55.00 to diagnose my Highlander's heater problem. They said they would have to order the part and I could bring the car back next week to get it fixed. I asked him how much it would cost and he said that he was embarassed to tell me that the heater control unit was going to cost $681.00 dollars to replace. After I picked myself up off the floor I asked him if that included labor. He said the labor would be another 165.00. The total to fix the car? 55 + 681 + 165 = $901.00!!!! And this doesn't include tax...
I did some research last night and came across this site and your post. It took me all of one hour this morning to pull the control unit out of the dash, open it up, solder in three new wires, and put it all back together. It works Great!!
I took my wife out to the movies tonight to celebrate the money we saved. I think the most satisfying part will be tomorrow when I call the dealership to cancel the appointment to have the car worked on.
Thanks again for your taking the time to post your Highlander experience here.
I took several pictures of the insides of the heater unit showing the before and after of the broken wires and the fix. I can post them here if anyone wants to see what the circuit boards look like and where the wire needs to be soldered.
Thanks again.
Don

Do you have pictures? I have the same problem but not sure what it looks like behind the panel. Thanks.

[captainsparkey]

Do you have pictures of how you removed the control panel from the dash board and the 4 screws? I have a 03 highlander...

[demitriff]

Wizzer!
Thank you so-o-o-o much for your solution to this problem and for posting the photos.
A good friend of mine, who is an excellent electronic technician, and I just put the rewiring fix into my 2003 Highlander and we are back in business with a perfectly operating heater... Nothing is better than beating an auto manufacturer out of robbing you. Toyota should've had a recall on this problem, at a minimum, to just tighten and secure the nut that comes loose on their badly designed heater knob assembly.

Meanwhile, some additional information and backgound for others with heater problems related to this loose heater knob(s) problem.

-The loose knob should be pulled off and tightened as soon as it seems loose and you can likely head off breaking the wires and going for the larger surgery needed for this fix. The knob is held on only by friction and can be pulled off without doing anything else to the dash. The nut holding the knob and its related circuit board in place is very easily tightened with a socket wrench. A dab of gorilla glue or even nail polish should help keep it secure.
-The middle knob and the one on its right are held on with a nut and have a circuit board integrated with them. The knob on the left should not have similar problems as it is a different configuration and assembly.
-Keep both the middle and the right hand knobs tightened at all times and you may be able to head off the larger repair described here.

-If you go into the dash to effect the repair of the broken wires, you can use butter knives and wrapped in a bit of cloth to pry off the bezel surrounding the heater and radio. Once you have enough of an opening between the bezel and the heater control unit to use your fingertips, go for it. They are the best for pulling the bezel off and least likely to damage the bezel or the unit itself.

-Once you have the bezel off, you have 4 screws to remove in order to get the heating control unit out of the dash. The screws are located at the upper left and right sides of the unit...two on each side, screwed in horizontally. Be carfeful with the screws not to strip the Phillips heads. The angle is a bit difficult, but doable. Easy does it.

-Once the four screws are out, you need to pry the bracket on each side through which they were attached to the heater control unit....again easy does it, and you will have the heater unit out and ready to work on.

-There are, if I recall correctly, 8 screws involved in taking the back of the heater unit off, including three on each side, top middle and bottom, and two screws nearer the middle of the unit at the top.

-The wire(s) you will find broken are those that attach at the small (1 inch square~) circuit board integrated with the loose knob.
-Before you go to work on the wiring, remove the knob and tighten the nut so that the circuit board is firmly seated again.

-We used the same technique as Wizzer used, that is, we replace the ribbon of 3 wires with 3 individual wires...however, if possible, we recommend minimizing the number of new solder joints you work with. It was our experience that any solder dripping between the 3 terminals on the large circuit board was extremely difficult to remove...and its easy to drip solder such that it bridges and shorts the terminals. Whatever material used at and around the three terminals on the large circuit board seems to provide a very solid bond with solder, even where you don't want it.

-If possible, only deal with soldering at the knob end of the connecting wires by just resoldieriing which ever of the wires was broken back to its terminal on the knob circuit board. Or, use pig tails soldered to the broken end off the ribbon wire and then to the knob circuit board.
-Using pig tails could be the best bet, as the use of more flexible wire in the connections should head off any possibility of future breaks should the knob come loose again.

OK...That's some more detail for anyone who wants to give this a try. Smaller hands are helpful for getting the wiring harness off of the back of the unit.The harness in back of my heater control unit was not particularly long and it was a bit difficult getting the connections off of the back of the unit at the dash when we were removing the unit from the dash.

The soldering work on this job is a bit demanding and best done by someone with a lot of experience, if you can get some help. My hat is off to my good friend, army buddy and best man, Donal, a true master technician, who did a great job on the wiring work and whose smaller, skilled hands helped us get the wiring harness disconnected from the back of the unit.

Worst case, if you're not up for the wiring work, just buy a junker heating control unit and just replace the whole shabang for a small fraction of what your dealer will get you for with their new replacement. Tight knob units only, however!!!

Again, Wizzer, thanks a ton for unraveling this puppy for all of us. My old friend Donal and I had a great time doing this fix today, and beating Toyota in the process!!

Best Regards,
Jim
Scarsdale, NY

[mantel34]

Just finished a successful rework on my wife's 2001 Highlander. Like most everyone, we were experiencing sporadic heat/cooling.

Wizzer.. you must be tired of being thanked.. but I have to tell you once more... Thanks!. And thanks to everyone else who's successful experience spurred me on to try the fix.

While I followed most everyones technique.. I ended up pulling out the entire radio/heater assy.. which is very easy to do. All you need to do is remove the 6 bolts (10 mm socket).. and the assy easily slides out giving plenty of room to remove the antenna and connectors. With the 2001 Highlander, you will need to move the shift level to low to allow the assy to slide out.

I also decided to replace the harness with three separte wires. I'm not sure of the exact gage, but I did use solid core copper wire (versus standed wire). While not an expert solderer.. I do have some experience thanks to building RC Helicopters... which means that having the right tools is the key.

I used a 40 watt soldering iron and a special soldering stand that has two aligator clips for holding wires in place.. an invaluable tool. I also followed the guidelines that less solder is better... which I feel helps reduce the heat required.

Like others, I first pre tinned all the wire ends. The solder pads (holes actually) already had enough solder left. The real challenge is soldering the wires in place.. to do this, I lightly pushed the wire against the solder (which is plugging the hole) then touched the opposite side of the circuit board with the tip of the solder gun. After a few seconds the solder flowed and the wire slid thru.. leaving a nicely formed solder fillet between the wire and pad. quick work is the key to keep from reflowing the adjacent wires!

This was fairly easy to do with the three loose wires going into the main circuit board... which I did first. Getting the wires into the switch's circuit board was tough.. four hands would be the best... but I only had two.. so I used the soldering stand's aligator clips to hold the wire, then, holding the board in my hand.. I repeated the process of pushing the tip of the wire against the solder pad and touching the opposite side with the solder gun..worked perfect.

Again.. thanks to everyone, because we all know.. a happy queen is a happy kingdom!

Ken

[apogue]

O2 sensor is code 1150 for the 2 at the manifold. I think 1130 is the one for the one at the exhaust pipe.
wizzer is correct, just hurts fuel economy as sensor adjusts air/fuel mix...
The one on the backside of the V6 is the one most likely to fail.
I just bought two of the parts Denso OEM equivalent (go to their site for the part #)
cheapest place was on amazon for $135 each. Don't get the universal one, use "front" for the manifold two and "rear" for the exhaust pipe one ($85?)

[MadeInMaine]

My 2002 Highlander had problems even when under warrantee. We lived in California at that time, and the air conditioner would just start blowing warm air. Jiggling the temp control would usually get it working at certain positions. Took it to our Toyota dealer and they could not duplicate the problem, worked fine for them. This summer the dang thing was acting up, I took off the knob and discovered the ring/nut that tightens over the stem of the heater control was loose, I tightened the nut and it worked better, seemed fixed.

Now it barely ever works for heat control or A/C, so after reading this forum, I took it to the local car stereo shop and had them remove it (having already determined that the tech would solder and repair if there was broken wires). Figured they are always in that part of the dashboard installing radios so it would be easy to have them remove the heater control and attached circuit board....

The tech brought out the board and showed me one wire was broken as has been reported in this forum. He replaced it with a new, somewhat longer, ribbon cable and it works like a charm. Thanks for saving me what Toyota had quoted me, around $1000.

Tom

[rsadkins]

Wizzer & Dfluitt:

THANK YOU SO MUCH for putting this info here...you saved me a TON of money!!

I have had the same heater problems for the last year or so and now that it's getting c-c-colder up here in Michigan, it has become more annoying lately. Yesterday it was bad & I could barely get the damned thing to work at all. So this morning I did a search for what the problem might be...thinking it might be a the thermostat or something. This is when I ran into your posts.

In under 3 hours, I had taken the heater unit out, gone to the hardware store to buy a solder gun, fixed the broken wires, and had it reinstalled, up and running!!

It's amazing that so much of a problem can come from simple little wires that come undone like that.

Well, I'm a happy guy...heater fixed and I'm not broke!

Thanks, gentlemen...you're awesome!

-Randy in Michigan