GM Truck Club Forum banner
21 - 27 of 27 Posts

·
Registered
2004 Silverado 1500 4WD Crew cab 5.3L
Joined
·
45 Posts
Discussion Starter · #21 ·
Fix, your over thinking this problem.
It worked until it got wet.
The 12 pin plug to a 24 pin connector worked before it got wet.
If it looks fine, put back together before you have numerous problems and you won't get it fixed.

The red wire that has no voltage is supposed to be a fused 12 volt always hot wire, that's where your problem is, figure out why the 12 volts has disappeared.
Your right of course, I was originally thinking that wire was being controlled by the control unit fan circuit but there's no red wire coming from the control unit. All the fuses are good. If you happen to know what fuse feeds that particular wire, I'll check the plug the fuse plugs into. Thanks for guiding me back to the path. I was getting into the weeds.
 
  • Like
Reactions: RayVoy

·
Registered
2004 Silverado 1500 4WD Crew cab 5.3L
Joined
·
45 Posts
Discussion Starter · #23 ·
After checking the fuse again and checking the fuse box, I rechecked the wire feeding the resistor. I had voltage at the resistor. When I checked voltage at the motor, I had nothing. The other day I had voltage both at resistor and motor but motor wouldn't spin. I rechecked continuity between resistor ground and ground going to motor and had an open. I must have an intermittant connection inside the reisistor ground path. I have ordered a new resistor and will post if it fixes it or not. I believe this intermittant connection might have been enough for my meter to read voltage but not enough connection to carry the amperage needed to spin the motor. I ran into something similar way back when working on a caterpillar loader with a brake light. Everything checked good with gound, light bulb and power, but ultimately found a recessed pin that couldn't carry the current needed to light the bulb but my meter could read voltage to ground. Hopefully this will fix the issue.🤞
 

·
Registered
Joined
·
1,605 Posts
There is always a 12V feed to the blower motor pin 1, then it goes to the motor internal windings then out to motor pin 2 then to the resistor pack. At this point, the motor will not power up because it is still missing a ground path. The rest of the resistor pack terminals are wired back to the climate control module where the blower speed is selected thru the Up/down speed control, then it is directed to a an external ground path then the motor runs at the selected speed.
At least that's how mine is wired.

If you try to bridge a wire from the resistor pack to an external ground path, see if the blower runs in high speed.
 
  • Like
Reactions: I fix planes

·
Registered
Joined
·
16,218 Posts
Bel, I'm not at home, so I don't have any drawings at my fingers; but I think the resistors are on the hot side, not the ground side.
I'll check it tonight.
 

·
Registered
Joined
·
1,605 Posts
It's possible the resistor pack could be on the hot side.
 

·
Registered
2004 Silverado 1500 4WD Crew cab 5.3L
Joined
·
45 Posts
Discussion Starter · #27 ·
After checking the resistor, fuses, grounds, etc. again and listening to ya'lls comments (bazar01, Rayvoy) it seemed to me that it had to be the control unit. There is a smaller black wire that comes from the climate control to the resistor. I wasn't getting any voltage from that wire and from pin out schematic I was able to find, it seemed like it might be a control voltage wire of some sort, maybe a 5V. I ordered a new one and replaced it. Problem is fixed, everything works like it should, I'm not sure how that all ties in with seeing no ground or continuity to ground since I don't have the schematic for the climate control unit itself. I won't burn to many brain cells thinking about it. I'm just happy it's fixed.Thank you all for helping, this is why I really like this site, there is an abundance of experience and hopefully this thread will help someone else in the future.
 
21 - 27 of 27 Posts
Top