Blower motor control diag

[Stiles97]

Hello all,
Does anyone have the wiring schematic available for the blower motor control on 1997 sr5 ? Mine has stopped functioning on the lowest speed. All other speeds work fine. It's been my experience that when the resistor fails all speeds other than high do not work. Thanks in advance for any help you can give ,
Matt

 

[IBallEngineer]

This is the 02 EWD. [MENTION=10169]TheDurk[/MENTION] might have the 97 EWD.

http://tacoma.site40.net/4Runner_96-02_Repair&Wiring/techinfo.toyota.com/ileaf/ewdtmc2/ewdtmpdf/ewdsourc/2002/024runne/systemci/057acman.pdf

 

[Stiles97]

So the resistor could be at fault. Either an open at on the last 'leg' of resistor or faulty ground wire coming out of resistor to ground or the control switch isn't energizing the relay in 'low' position. I imagine this is very similar to what I have. Hopefully TheDurk can chime in. This gives me a good starting point though! Thanks ,
Matt

 

[TheDurk]

This is the 02 EWD. [MENTION=10169]TheDurk[/MENTION] might have the 97 EWD.

http://tacoma.site40.net/4Runner_96-02_Repair&Wiring/techinfo.toyota.com/ileaf/ewdtmc2/ewdtmpdf/ewdsourc/2002/024runne/systemci/057acman.pdf

'97 is the black hole in my EWD collection. I have '96, '98, '99, '00 is same as '99, '01 is same as '02, and '02 is on-line for everybody. '97 I got nuttin.

But in this case, '96 and '98 are the same as '02 for blower, switch and resistor so just go with what was posted.

 

[Stiles97]

So continuity check between pins 1&8 of blower switch, with switch in low position. That will tell if it's the switch. Continuity between 1&4 of the resistor, not sure what I will see there but as long as it's not 'o.l' should be good and then the ground wire from pin 1 of the resistor connector to ground for continuity. Missing anything ?

 

[TheDurk]

Well, the full check of the switch is spelled out:


8-1 : Closed with blower SW at LO position
8-6, 1 : Closed with blower SW at M1 position
8-5, 1 : Closed with blower SW at M2 position
8-4, 1 : Closed with blower SW at HI position

But you have scoped it out pretty well. If the relay energizes in LO, its the last leg of the resistor or the wire to T1. If it doesn't, it's the switch. Good luck!

 

[IBallEngineer]

[MENTION=110630]Stiles97[/MENTION]

I'm at a loss for words. Usually [MENTION=10169]TheDurk[/MENTION] and I are offering help to forum members who ask for help then start replacing the ECU to solve the left headlight issue.

 

[nissanh]

The resistor is for 1,2 and 3 speeds only. 4th speed is direct 12 V to the motor.
There are 4 wire pins. One is the supply 12V. Through the first resistor coil you get the 3rd speed. with the first and second resistor coils in a series you get the 2nd speed and with all 3 coils in the series you get the lowest speed.

 

[Stiles97]

So it is in fact a faulty blower motor resistor. Will post some pics of the resistance reading on the working portions in case others may find it useful. But here is the resistor as I took it out of the housing. Thanks to TheDurk and Iballengineer for the help !

 

[Stiles97]

Pin 4 to pin 2 of blower resistor measured 0.6 ohms

 

[Stiles97]

Pin 4 to pin 3 measures 1.0 ohms

 

[Stiles97]

Then the last reading( the one I was most interested in ) between pins 4 and 1 measured 2.88 m ohms. Although there is a reading, it is so high that it is essentially an open circuit and the cause of the blower motor not working on the lowest speed setting. Even though it's a cheap enough part to just throw at it, it's nice to know for sure. Thanks again for the help ,
Matt

 

[Stiles97]

Got the new resistor installed and everything is good now. Little time and $20 bucks and it's fixed

 

[FreshYoungDude]

Thanks for sharing this info guys, mine doesn't work on "Lo" either. My fan seems obnoxiously loud on the other speeds too.

 

[Stiles97]

Thanks for sharing this info guys, mine doesn't work on "Lo" either. My fan seems obnoxiously loud on the other speeds too.

My guess would be that you have debris ( leaves / pine needles) in the blower motor housing along with a faulty resistor. It's fairly easy to inspect.
Matt

 

[gamefreakgc]

My guess would be that you have debris ( leaves / pine needles) in the blower motor housing along with a faulty resistor. It's fairly easy to inspect.
Matt

How did you remove the leaves? A few small ones made their way in there about a month ago. Did you just drop the motor out?

 

[FreshYoungDude]

Stiles, where is that resistor located? I want to check mine out too. Electrical stuff makes me cringe. Thanks for helping.

 

[TheDurk]

My guess would be that you have debris ( leaves / pine needles) in the blower motor housing along with a faulty resistor. It's fairly easy to inspect.
Matt

Yep. Here is what happened to mine, sounded like a jet plane on take-off:

 

[FreshYoungDude]

Holy crap lol!

 

[Stiles97]

Stiles, where is that resistor located? I want to check mine out too. Electrical stuff makes me cringe. Thanks for helping.

Right next to the blower motor. 2 bolts holds it in. It bolts into the blower motor housing/box. If I recall correctly I had to maybe pull the glovebox lid off but I don't remember. I can look at my service manual later this evening as my truck isn't here at the moment. Or I'm sure thedurk knows