Heater fan and wipers quit working

Tiny
WHITEMFOX
  • MEMBER
  • 1999 GMC SAFARI
  • 120,000 MILES
Heater fan and wipers quit working. Replace resistor and wiper pulse board, still nothing. I ran a hot wire over to the wiper motor plugin to check if the motor was bad, wiper motor came on and so did the heater fan and so did the dome lights. I disconnect the hot wire all goes dead again. I am totally confused on this one.
Sunday, February 19th, 2017 AT 3:33 PM

5 Replies

Tiny
CARADIODOC
  • MECHANIC
  • 34,194 POSTS
Do you have cruise control and power windows? If so, are those also dead? You have to look for what all these things have in common because obviously so many different problems did not occur at once. Check the "IgnB" 40-amp maxi fuse in the under-hood fuse box. If it is okay, check for 12 volts on both test points on that fuse. If you have 12 volts on both sides, the ignition switch is the best suspect, especially if the heater fan is used on the highest speeds often.

Go to the fuse box inside and find fuses 6, 12, and / or 18. Check for 12 volts on them when the ignition switch is in the "run" position. If it's missing there, inspect the connector body and terminals for the ignition switch. If two or three terminals are black, and the connector body is melted, I will describe how to repair it.
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Sunday, February 19th, 2017 AT 5:11 PM
Tiny
WHITEMFOX
  • MEMBER
  • 3 POSTS
Discovered I have no power to some of the fuses on the inside.
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Monday, February 20th, 2017 AT 10:56 AM
Tiny
CARADIODOC
  • MECHANIC
  • 34,194 POSTS
Which fuses? If it's the three I listed, go to the ignition switch and inspect the connector and its terminals.
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Monday, February 20th, 2017 AT 6:13 PM
Tiny
WHITEMFOX
  • MEMBER
  • 3 POSTS
Yes, it is the three you mentioned plus #11 I haven't had time to get the ignition switch yet. Hopefully within the next couple of days.
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-1
Monday, February 20th, 2017 AT 6:33 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 51,872 POSTS
Please let us know happens so it will help others.

Best, Ken
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Thursday, February 23rd, 2017 AT 12:36 PM

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