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
Re: Heater quit... sort of
Re: Heater quit... sort of
