This article shows top 5 problems with the 1st generation GMC Sierra from 1999 to 2006. If you or your friends have one, check out this article, so that you can know what to keep an eye out for with yours. More cases about GM, please refer to GM Vehicle Repair Cases.
No. 1 Headlight switch
The headlight switch is located in the dash.
You may notice that your headlights aren’t working properly, no matter what you do. You want to double check the bulbs and double check the fuses but most likely it’s just the switch itself. It’s really not that hard to replace this , you have to do is take trim piece off then you can access the switch itself, disconnect the connector and put the new switch on, put it back together and you’ll be good to go.
No. 2 Turn signal switch
You may notice while you’re driving down the road, you hear a little bit of clicking noise coming from the turn signal switch, it sounds like it’s trying to activate the turn signal switch but it’s not. The only solution for this is to replace the multi-function switch or the turn signal switch.
No. 3 Front wheel bearing
You may noticed while you’re going down the road, it sounds almost like a helicopter or an air plane loud type noise coming from the front of the vehicle. You may notice that it also changes from going side to side if you’re taking a left turn or right turn, it may get louder or quieter. Some times the wheel bearing will be noisy and have play, you can grab the top of the tire in the lower of the tire and just shake it.
You may find you got a lot of play. Sometimes they’ll be quiet and have play and either way the wheel bearing needs to be replaced.
To replace the wheel rings you need to take the front wheels off, take the brakes apart, take the caliper and the rotor off and then you can access the wheel bearing, replace that and put it all back together.
No. 4 The Encoder motor
It located on your transfer case.
The symptom is your four wheel drive isn’t working and you probably have a service four wheel drive light on. If you scan that light you probably have a code C0327. What that code means is there’s a sensor inside the encoder motor that tells the computer where it’s located where the transfer case is , whether it’s in four wheel drive or two-wheel drive and that sensor is not working properly , so it shuts everything down. If you have this problem you always need to check connectors and you always need to check wiring out, but most of the time what you can do is take the transfer case encoder motor out. You have to remove the front drive shaft, take the encoder motor off and you can actually take it apart and replace just the sensor.
No. 5 Front Impact Sensors
Some vehicle have two of them located at the base of the radiator, some vehicle only have one in the middle of radiator. The symptom you’re going to notice is the airbag light on and you probably have a code for those front impact sensors.
Replace the sensor it’s pretty easy, you just need to disconnect the battery first and then disconnect the sensor. There is a little lock tab there, you have to pull that out. Disconnect the connector and then there’s a 10 millimeter bolt that holds the sensor on, then you need to take that 10 millimeter bolt out take the sensor down, you can put a new sensor in, reconnect the connector connect the battery and you should be all set. One of the reasons why these sensors go bad is corrosion where the bolt actually goes through the sensor corrodes and cracks the sensor moisture gets in there and break the sensor.