Where is low pressure port on a/c system on 1998 gmc sierra truck

SOURCE: gmc sierra 2008 low tire pressure problem

You can follow this to reset it.
Ignition ON, initiate the TPM Learn Mode
using one of the following procedures:

1. On vehicles equipped with keyless entry, simultaneously press the keyless entry transmitters lock and unlock buttons until a double horn chirp sounds indicating the Learn Mode has been enabled. The left front turn signal will also be illuminated.
   
2. On vehicles not equipped with keyless entry, press and release the driver information center (DIC) INFO button until the TIRE LEARN message appears on the DIC display. Press and hold the SET/RESET button until a double horn chirp sounds indicating the Learn Mode has been enabled. The left front turn signal will also be illuminated.
3. Increase/decrease the tire pressure for 8-10 seconds then wait for a horn chirp. The horn chirp may occur before or up to 30 seconds after the 8-10 second pressure increase/decrease time period has been reached. Once the horn chirp has sounded, the sensor information is learned and the turn signal in the next location to be learned will illuminate.
   After the horn chirp has sounded and the right front turn signal is illuminated, repeat step 2 for the remaining 3 sensors in the following order:
   3.1. Right front
   
   3.2. Right rear
   
   3.3. Left rear
   
   When the left rear sensor has been learned and a double horn chirp has sounded, the learn process is complete and the RCDLR exits the learn mode.
   Ignition OFF, adjust all tires to the recommended pressures

SOURCE: 1998 GMC Sierra radio and display stays on all the time

First of all...does your truck have the retained accessory power (RAP)? If it does, the radio would always stay on with the key off until you open the drivers door. If it does have RAP and the door pin on the drivers door has went bad, then the truck doesn't know that you opened the door and continues to allow accessory power (although it would still cut off after about 20 minutes). If the interior lights come on when you open the door, then the pin is ok. If the lights come on, it could be the RAP relay. If it has gone bad, it is possible it is stuck supplying power and needs replacing. The relay should be labeled in the fuse panel, and there should be other relays in the panel with the same part number. You can swap a relay for the RAP relay and see if it fixes the problem...if it does fix it swap the relays back and replace the RAP relay. If the truck doesn't have RAP then it is possible the problem is in the radio..if you have a friend with a GM car or truck close to the same year you could swap radios and see if that fixes your problem...should be pretty simple. pull the cover off the dash, it just clips on, take out a couple screws that hold in the radio, unplug it and plug in the other radio. sorry so long winded...hope this helps you somewhat.

Dave C

• 1050 Answers
• Posted on Mar 19, 2009

SOURCE: rough idle,runs fine on highway

It is possible that the regulator is leaking into the intake plenum, or one of the injector lines has a bad O-ring and is doing the same thing. This was actually a big problem with this system on the 4.3L engines, but it is a little different on the 5.7. Before tearing into this this though, I think it would be a good idea to get a professional diagnosis. I would start with a compression test. The miss could be caused by low compression in one or more cylinders. The injector assembly has the regulator mounted right on the side of it and the whole assembly resides inside the intake plenum. It is not that difficult a job, requires some patience and skill, the worst part is the cost of the parts.
I've attached a picture of the injector assembly with the reg attached and highlighted

SOURCE: 1998 GMC Sierra pickup truck cabin fan problem

Your blower moter is under your glovebox and very easy to replace.I dont think thats your ploblem.I would pull off the dash.It will snap right off without breaking anything.Then pull out the part that holds the selector switch for the fan speed.Then you unplug that switch.Clean the copper contacts.Plug it back in.If everything works again like it should and did in my truck then it is either that switch that is bad or the wiring harness.I would replace that switch.

SOURCE: 2003 GMC Sierra Knock sensor and oil pressure??

the knock sensors are located below the intake plenum,or,upper intake manifold as some call it, they screw into the lower intake, the front one is sensor 1, the rear is sensor 2. it is wise to change both if you have some miles.since you are going to be buying a gasket set to do this job.the sensors are cheaper than the gaskets.