Blower motor issue-I’ve read several threads
 

Just bought a 1989 x-cab 4wd pu and heater blower doesn’t work. Google got me to this forum and some good info to know where to look. 30A fuse is good. I pulled the blower motor and when hooked direct to 12v battery it runs fine. Resistor was shot so I installed a new one. Plugged motor in and nothing… checked power at motor plug and all fan power settings show 12+ volts. What am I missing? The switch sends power on all speeds.

the blower itself is on its way out, even though it worked with power directly to it. i just dealt with exactly the same circumstances last month. resistor was fine, fuse still worked, and when i bench-tested the blower, it worked. however, while bench-testing, if i turned the blower on its side or upside down, it would stop. swapped in the blower from my '88 parts runner and the heater/blower works correctly again.

Thank you for the info. I’ll check on it. One strange thing is even though my meter shows plenty of volts at the motor plug my test light bulb won’t illuminate at the same plug with the voltage, like maybe not enough amperage. What would cause low amperage in this situation?

Old 11-06-2023, 11:53 AM
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Willamette519
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Thank you for the info. I’ll check on it. One strange thing is even though my meter shows plenty of volts at the motor plug my test light bulb won’t illuminate at the same plug with the voltage, like maybe not enough amperage. What would cause low amperage in this situation?

The switch grounds the motor, it doesn't power the motor. You should have one wire 12+ and the other is grounded on high, and grounded thru the resistor pack on the other settings.

This is the important part. You'll find 12v to ground on the motor at all times; it is only when you ground the "other" lead of the motor (through the resistor) that it runs.

Many other parts of your vehicle (headlights, door locks, injectors, etc.) are switched-ground.

Any update?

No, I’ve not had a chance to get back to it but will this weekend. The info of the switch grounding the motor should really help. I’m not one that understands automotive electrical well at all. All help is appreciated. I’ll post whatever I find that fixes the issue because it appears to be somewhat common, with seven different potential causes.

Looks like I identified the problem. Here us what I checked before finally finding what appears to be the issue:
The 30A fuse for the blower motor. It was good, as was the 10A fuse above it for the relay.
Motor checked on a direct connect to battery and was good.
Checked the resistor and it was shot so replaced but did not fix problem.
I removed the Toyota 90987-04002 relay that is directly above the blower motor fuse box. I jumped across the two large blade slots and the blower motor kicked on and all the speeds on the switch worked great, with the motor increasing speed accordingly. My assessment is the relay is bad. If I replace it and it doesn’t fix it I’ll post on this thread again. I found how to assess it and identify the relay as the problem in an 18 year old thread.

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Is this the relay to the left of the glove box?

Could you share a pic of what you jumped to get the motor to blow?

I am fighting a blower that will not work.

So far have checked fuses: all good.
Replaced blower motor.
Replaced resistor.

As I understand it, I should have power at the small plug leading to the motor?? If I am checking right, I am not seeing power there.

I would appreciate some help and sorry for poaching on your post Williamette.

I can’t do pics because everything is back together. To the right of the blower motor, up against the right side of where the glove box goes is the fuse and the relay. Pull the relay and use a text light to find the hot lead to the relay. I think it was one of the larger blades. Jump a wire across to the other large blade. Plug the motor in and see if it works when you turn the fan on. If the fan works then it is the relay. At least it was with mine. Sorry for delay in responding and sorry I can’t be more precise on which blades on the relay to jump. It made sense when looking at it when it was all pulled apart.