91 Camry Blower Switch: Only 1 of 7 Incoming Plugs Is Hot?

[byuauhunter]

Gotta preface this by saying I'm pretty clueless when it comes to even the basics of electrical.

The blower stopped working at ALL speeds on my 91 Camry. Low and Medium had been out for a while so I replaced the blower resistor knowing that was the issue with low and medium. (a few broken coils).

Didn't work.

I checked all the fuses under the hood and the set by the driver's side feet, all good. I tested the blower motor directly and it spins.

Used a 12 volt tester and verified no power was getting to the motor. According the Haynes manual the only thing left ought to be a bad blower control switch.

I removed the center panel and removed the switch. Cheapest I can find is $50 online.

Concern: I tested the wiring harness that plugs into the back of the switch to see if it was getting power. There are 2 Large female plugs on top and 5 small on the bottom (3 grouped together in one spot, then 2 in another). So 7 spots total (2 large, 5 small). Only one had 12 volts coming in and it happened to be one of the small ones in the cluster of 3. I don't know anything about electricity but that seemed odd. I would think more than 1 of the 7 incoming wires into the blower switch should be hot.

Am I right to be concerned? I just don't want to drop the cash on this part if it's something else. Any suggestions?

Is there any way to test that switch with my Fluke multimeter to verify it is bad?

[auto_robotics]

The fan should always work on high, even if the blower motor resistor pack is shot, so either 12V or ground is missing from the motor.

12V comes into the motor in this order:
- battery
- 80A ALT fuse
- heater circuit breaker (in the passenger's side kick panel)
- heater relay (in the passenger's side kick panel)

The heater relay is controlled by the blower switch. It sends 12V to the motor on every speed but OFF. Make sure that the 7.5A GAUGE fuse (in the driver's kick panel) is fine -- it feeds the relay.

Ground is connected to the motor through the blower switch.


To test the switch:

Visualize the connector on the switch like this:
retention tab on top (upside down from how you described it)
[5 4 3]___[2 1] (small pins)
___8___-___6 (big pins)

8 is ground.
6 goes to the motor for HI (grounded).
5 goes to control the heater relay. Grounded sends 12V to motor.
3 and 4 are for the illumination circuit. 4 is 12V when the parking/headlights are on, 3 is the rheostat.
1 and 2 go to the resistor pack.

HI: 6 and 5 will be shorted to 8 (only)
Speed 2: 1 and 5 shorted to 8 (only)
Speed 1: 2 and 5 shorted to 8 (only)
LO: 5 shorted to 8 (only)
OFF: everything disconnected

Hope that helps! (and I didn't mess up anything )
- Craig

(This assumes you have the lever type -- you didn't say which.)

[white90dx]

Is it a base/DX or an LE car?

-Charlie

[byuauhunter]

Autorobotics: Thanks for the insight. Very helpful.

So I popped my old one out. I assume I should be able to verify the switch is bad with a multimeter? I may be way off, but I assume if the switch is bad none of the pins would have continuity between each other even when they are supposed to? Meaning the circuit is broken when it shouldn't be?

I flipped my multimeter to continuity (I only figured out what that did a few days ago...) and checked for continuity between each pin and all others in every lever position (Off, Low, 1,2,HI). I expected to get nothing.

I printed out your diagram, set the multimeter to continuity and checked. Here are the results:

HI: Continuity between the following: 6-5,8-5,6-8.
Speed 2: Continuity on 1-8,5-8,1-5
Speed 1: Continuity between 2-8,5-8,2-5
LO: 5-8
OFF: Nothing

Based on what you said, this makes me think the switch is fine? But I have no idea what else it could be. Am I doing this right and if so, do my results indicate to you that the switch is good?

I was a little confused as to why I'd get continuity between 6:5 on HI, 1:5 on 2, and 2:5 on Speed 1 but I assume that's just something I don't understand about electricity and switches...

Any thoughts?

Thanks again.

[byuauhunter]

Charlie: Forgot to mention that. It's a Base model. Lever type controls, not the electronic push button.

[auto_robotics]

It sure does look like your switch is working properly.

How about you check the power sources I mentioned next? The ALT and GAUGE fuses, circuit breaker, and relay.

With the switch plugged in and set to any speed but OFF, make sure that there is 12V on pin 1 of the motor cable.

The cable should look like:
retention tab
1 (wider)
2 (taller)

If the fuses are good, and there's no 12V on pin 1, I'd unplug the heater relay and check to make sure it's getting 12V from the circuit breaker.

The socket for it should look like:
3__5
2__-
1__4

5 is 12V from the circuit breaker
4 outputs 12V to the motor when 1 is grounded by the switch
3 is 12V from GAUGE
2 is grounded
1 goes to pin 5 on the switch

If all that checks out, I'd say replace the heater relay. If there's no 12V from the breaker, I'd say replace the breaker. Actually, are those things resettable? Check first.

- Craig

[white90dx]

When you test the switch, you will need to unplug the fan speed resistor, otherwise you will get false readings like you did. Either way, it seems like the switch is working.

Since that is the case, you will want to check/replace the 40A Heater Circuit Breaker and the Heater relay.

-Charlie

edit: Beat me to it.

[byuauhunter]

Originally Posted by auto_robotics

It sure does look like your switch is working properly.

How about you check the power sources I mentioned next? The ALT and GAUGE fuses, circuit breaker, and relay.

With the switch plugged in and set to any speed but OFF, make sure that there is 12V on pin 1 of the motor cable.

The cable should look like:
retention tab
1 (wider)
2 (taller)

If the fuses are good, and there's no 12V on pin 1, I'd unplug the heater relay and check to make sure it's getting 12V from the circuit breaker.

The socket for it should look like:
3__5
2__-
1__4

5 is 12V from the circuit breaker
4 outputs 12V to the motor when 1 is grounded by the switch
3 is 12V from GAUGE
2 is grounded
1 goes to pin 5 on the switch

If all that checks out, I'd say replace the heater relay. If there's no 12V from the breaker, I'd say replace the breaker. Actually, are those things resettable? Check first.

- Craig

Hmm, I was afraid you'd say the switch was still good... I'll check for the fuses you mentioned. My Haynes manual didn't mention anything about a Heater Relay or Circuit Breaker in the section on diagnosing an inoperative blower fan. But unfortunately that doesn't surprise me, I've noticed lots of stuff over the years that isn't mentioned but ought to be...

Another stupid question: What and where is the 2 pin motor cable you mentioned? Is that behind the center panel as well or somewhere else?

Also, anyone have any recommendations on how to find diagrams or schematics on your vehicle if you can't find it in a Haynes/Chilton manual? I figure there ought to be something on the internet somewhere... As I mentioned my book doesn't show a heater relay or circuit breaker but I'd dig around the passenger side and hopefully it's obvious. Just be nice if the manual showed what I was looking for...

[white90dx]

Originally Posted by byuauhunter

Also, anyone have any recommendations on how to find diagrams or schematics on your vehicle if you can't find it in a Haynes/Chilton manual? I figure there ought to be something on the internet somewhere... As I mentioned my book doesn't show a heater relay or circuit breaker but I'd dig around the passenger side and hopefully it's obvious. Just be nice if the manual showed what I was looking for...

Toyota is pretty good at taking down the factory manuals whenever they are posted up. PM me your email address...

-Charlie

[auto_robotics]

I thought you said in your first post that you tested the blower motor directly? That should be the 2-pin connector I'm talking about. It's the one that plugs into the motor on the passenger's side.

- Craig

[byuauhunter]

Big thanks to both auto_robotics and white90dx. You both helped a ton. It turned out to be the heater relay. O'riellys wanted like $60 and a week to get here so I found two at a local salvage yard for $2 a pop.

No way I could have done it without the advice. Learned a ton in the process. Thanks!

[auto_robotics]

Hey, you're welcome, I'm glad you got it fixed!

BTW, a new heater relay should be closer to $20 than $60. If your salvage yard finds give out, check the net for part 90987-04002-83.

- Craig