GMC Sierra 1500 Questions

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My horn stops working one day then starts again the next and so forth. Im trying to figure out the problem. I checked the fuse and the fuse is fine. Im not sure where exactly the horn relay is located and I also believe I only have the one horn on my model(drivers side under headlight) because when I activate the locking alarm it makes the same pitch sound as my actual horn. Not high or low. Maybe the line is corroded due to rain or maybe its a bad connection or have gotten some water on the horn. Any ideas on how to fix the problem? Also I'm looking for the horn relay so I can check it. Its not in the under hood fuse box with the other fuses so maybe they put the relays somewhere else?

air doesnot blow out of the vents on the dashboard only blows out of the vents on the side of the dash board and the console. its cold though.i want to know why it is not coming out of the dashboard,

Second set of disc brakes since I have owned this truck. I have replaced everything from the hub out on both sides: rotor, caliper, and brake pads. I still get lots of noisy clanking from the front brakes when under way,especially if I hit a bump or hole in the road. A little pressure on the brake pedal and "wa-la" no noise...???????

Driving down highway and cruise control just quits. During those faults the left turn signal also does not work. Switch off and back started again usually fixes the problem?????

When in park I can increase the throttle manually and it will increase but still has a little miss.

Checked fluid in front transfer case...a little low but no metal shavings.. Jacked up both front wheels and can only turn them about a half of a turn or so

I am taking a long trip. My mechanic says the next thing which will probably fail is my water pump. It is a 4.8L V8 in a quad cab pickup. I am not showing any leaking at 145,000 with original pump. Would it be prudent to get a water pump replacement before my trip?

It only stayed on for a second and when right off, and hasn't been on since. I was switching from HIGH to see if the light would come on, but it has not displayed again. Wondering if I have anything to worry about. My truck is a 2001 with 120,000 miles...but it is in MINT condition. Any advice would be helpful! Thank you in advance!

my 6 month old 4L60 trany (still under warranty) acts as though it's slipping going into 2nd. It does not do it from a stop. Only when I slow down below 20mph then accelerate. I contacted the manufacturer and they said check the MAF. After further examination I discovered 4 codes have been set off. P0171, P0174, P0300, & P0332. After researching these I've come to realize there's more to it than the MAF. From what I can see the MAF is clean and good. Unless there's a problem in female end of the connector. I don't have the money nor time to just start replacing parts. Where should I start in order to fix the shift issue so I do not ruin my brand new trany and potentially void the warranty?

While sitting still I can turn the knob to any speed 1-5 and get nothing. Once I get to above 30-40 I get air but only blows low speed regardless of what number the dial is on. At highway speeds it's steady but low. If I turn the knob to off it turns off. If I push the "cold" button (the snowflake) it lights up, air even comes out cold, but only once I'm up to speed. So in other words it works when I'm moving, doesn't when I'm not. It's like the a/c works but it'll only blow when I'm driving. I don't know if this makes sense to anybody but me, but help if you understand hahah.

I have changed the control panels. worked for a very short period. I believe that it may be the actuators

If I shut it off and re-start it. The light will stay off until I start it again. Brake performance is still perfect

I lose coolant frequently but I have no leaks,I also lose oil with no leaks.

After my engine has been running for a mile it will slows down and over heats a little and feels like the engine is not getting enough fuel but got my fuel pump checked and it is fine. I have replaced the throttle sensor and fuel pressure sensor and still nothing. Any suggestions? Weird thing is that the check engine light won't turn on not even when you turn the key before starting the engine.

check engine light comes on - info panel says engine is hot but
all the instrument panels say normal - truck has 61,670 miles
on it

Problem started after the trucks battery and fuel pump messed uP 4 days ago. Fuel pump replaced and we got a new battery The same day. Basically we have to continuously flick the turn signal/hazard button off and on in order to make the light appear to be flashing. We didn't have any lights at first and before the lights died the blinker was making a weird noise while just barley flashing. I got a new relay And that got the lights on and got rid of the noise but they don't blink. Not sure where to go from here.

drivers side leak under dash

And it reduces my engine power and I turn off truck for a little while and start it its all goes off but a little while after driving it comes back on and does the same. What could be causing it?

leaks water on drivers side when it rains from under the dash

i think there is a faulty switch in the dash that switches from heater to vent to ac. i dont know where that is .