1988 Chevy Truck 4 wheel drive-a/c,heat

1988 CHEVROLET TRUCK
150,000 MILES • V8 • 4WD • AUTOMATIC
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RUDY910
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when u shift 2 4wheeldrive it blows the fuse for a/c,heat
Nov 27, 2009 at 9:23 AM
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DR LOOT
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you got me, I have never heard of that problem, are you sure your diagnosis is correct?
Nov 27, 2009 at 5:46 PM
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RUDY910
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yea im sure my diagnosis is correct. it always blows the fuse and the 4wd dont work when that happens
Nov 29, 2009 at 12:23 PM
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DR LOOT
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I am sorry you are correct, I was checking the wiring diagram on your truck, the AC/Heater fuse is connected to the trans-case, it get its power Supply from the speedo fuse, my question now is, dose your speedometer work? if it does. Most likely it is this which in the transfer case, that is grounded in other words, it is no good. because every time you put the transfer case in 4 Wheel Drive. The fuse blows.
Nov 29, 2009 at 12:57 PM
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RUDY910
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Yea my speed ohmeter works. we finally figured it out. thanks for the help
Nov 29, 2009 at 1:35 PM
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HILDY43
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how did yopu fix it i have this prob now!
Jan 24, 2011 at 1:43 AM
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DR LOOT
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replaced (VSS) on the back upper side of transfer case, make sure you wiring harness is not damaged. Let me know if you need anything else.
Jan 24, 2011 at 2:32 AM
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HILDY43
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what is a vss? when i unpluge the indicator light from under the truck my heat works fine but i dont think i have 4x4 yet?
Jan 24, 2011 at 3:16 AM
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HILDY43
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my truck is also a 5 speed...
Jan 24, 2011 at 3:17 AM
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DR LOOT
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5 speed manual?
Jan 24, 2011 at 3:45 AM
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HILDY43
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yes
Jan 24, 2011 at 3:54 AM
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DR LOOT
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Let me restudy the situation and I will get back to you, anything else you want to tell me go-ahead
Jan 24, 2011 at 5:27 AM
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