Results 1 to 2 of 2

Thread: Testing heater relays

  1. #1
    Join Date
    May 2013

    Default Testing heater relays

    1993 GMC Sierra 6.5 turbo -- I am having issues with the heater speed. Switch seems to be alright. There are 4 identical relays behind the glove box, and going through to find the bad one by replacing each with a known good, new one does not seem to be doing the job. I now have no low speed -- and would very much like to be able to have the fan speed. Does anyone know of the wiring diagram for this relay? Aftermarket BWD R3012 is the relay.
    Many thanks.

  2. #2
    Join Date
    Feb 2007
    Baja California Sur Mexico


    Make a search on this site, there is a resistor on top of the fan, almost imposible to get at, it fails.
    Grant H.
    1995 6.5 turbo GMC K2500 extra cab 4x4 pickup, PMD under bumper, mechanical wastegate, 228,000 miles, rebuilt engine, 4.10 diff, 16 mpg
    1994 6.5 turbo GMC K2500 4x4 suburban "F" VIN #9 resistor, PMD in the bumper, mechanical waste gate, 226,000 miles, Positrac 3.73 diff, 17 mpg highway.
    1982 4x4 shortbed 6.2 Chev 260,000 miles untouched motor 17 MPG 4.27 diff. Best thing I ever owned, 21 years.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts