I have an 01 1500hd and had the same problem, turned out it was the wrong part number. The one you bought is for auto climate control I believe. I bought ACDelco 12450120 and now the auto headlights and DRLs function properly. Sent from my iPhone using Tapatalk
Put a new dorman HVAC control unit in and no change. Still puts itself into recirc even when the unit shows that fresh air is selected. The fact that the auto headlight condition effects it makes me think there is a voltage draw of some kind that makes the actuator change with lights on/off or with acceleration. Thing is driving me nuts but I can’t find any other sensor that would be related to what I am seeing. Everything else works as it should. Sent from my iPhone using Tapatalk
2001 1500HD LT, manual AC controls....had the recirc/fresh air actuator making noise so I bought a new ACDelco replacement. Got it put in and door moves with no noise. Now for the issue. If I have it in fresh air mode and the auto headlights are on at start up, it will move and go to fresh air, but once I start driving and the RPMs go up I can hear the sound of the blower change (louder like when its in recirc mode). When I stop at a light I can hear it change back to fresh air and then back to recirc when I start driving again. Mode button light remains on for fresh air. Similarly, if I start it and the auto headlights are on and mode is in fresh air I can hear that its pulling fresh air from outside. If its daytime and the auto headlights turn off, as soon as they click off I hear the recirc door move and the blower sound increase. Mode button stays lit up for fresh air and I can visually see that the door is now in the recirc position. If I activate the recirc button the light stays on recirc and it never does any of the changing with RPM or auto headlights on or off. Any ideas on whats going in or what to look for? Sent from my iPhone using Tapatalk
Thanks...is there a diagram by chance? When I had the dash cover off, the one on the passenger side at the base of the A pillar was easy to find. I looked pretty extensively on the driver side and couldnt find a stud or anything that looked like a ground point with anything attached. Is the one at the bottom of the B pillar just for the seats? Thanks in advance!
Another question...anyone have a pic of the ground point under the dash on the drivers side? G203 possibly? When I had the dash cover off I found the ground point on the passenger side with two smaller wires. Cleaned up that connection with no change. Looking on the drivers side I could not find anything that looked like a ground connection under the dadh cover. Checked behind the light switch/AC vent and even behind the kick panel near the floor...nothing.
I have an 01 1500HD with about 110k on it. I have owned it for 1.5yrs and when I first got it the DRLs and auto headlights worked properly. A while back I started having the headlights turn on evertime I started the truck (day or night) and have to do the dome override all the time. I have done a ton of searching/reading and done the following: I changed DRL bulbs - nothing. Sockets looked burned so I changed them - nothing. Checked fuses and swapped relays - nothing. Put a new ambient light sensor in - nothing. Finally tried a new headlight switch - still nothing. Pulled the BCM to see if there were any cracked solder joints or anything looked burned - nothing. Tried cleaning ground points and ran a few redundant ground lines for battery/body/frame - nothing. Codes from the BCM are: B1477 B2585 B2617 B2647 B3102 I dont seem to have any other weird electrical issues that would lead me to believe the BCM is bad.... Does the Ambient light sensor route thru the BCM and headlight switch only or does it go thru the HVAC controls as well? Any other ideas? I would like to avoid paying to have it fixed if I can do it myself, but I am at a loss. Thanks!
Rear main requires dropping the transmission from the engine in order to access. The speed sensors are either connected to the tailshaft of the tranny or to the transfer case if equipped. When I replaced the tranny in my old 99 silverado I had similar issues to what you describe due to hooking up the wiring harness to the wrong sensors. 4x4 has three speed sensors in the transfer case all with the same connectors. Changed my connections and all was good. Sent from my iPhone using Tapatalk
I had an issue when I swapped the tranny in my 99 silverado. Mine is 4wd and I had incorrectly connected the three speed sensors on the transfer case tail housing. Had brake warning lights on and wouldnt shift out of first. Check those sensor connections.
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