02 GMC Sierra airbag problem

MonteStyle · 09-19-2009, 09:10 PM

Hi, new to forums but I have a lil problem with my airbag suspension.

First of all I didn't install this myself. The previous owner did everything to it himself, and have to admit I'm a rookie when it comes to this stuff so I hope that someone can help me out here.

First off the compressor. Was working fine for awhile but one day it would not come on. It only chooses to come on when it thinks it should, guessing it detects the PSI in the bags then comes on when needs to. Needless to say, I was driving and started noticing the truck was getting a little to low for my tastes, I switched on the compressor and it would not come on. Turns out I somehow burned the power wire under the truck. Got that fixed and it works now but ever since then it literally needs the truck to be on the ground for the compressor to come on, sometimes thats not even enough. Come back 3 hours later THEN when I flip the switch it comes on. Someone suggested that I might need a new Pressure Sending Unit or something to that effect.

Secondly all the switches for the truck were working fine until today when the left rear one don't want to lift up. It will go down just fine, but when I hit it to go up it wont. All the others are fine. Ive tried the "side" and "back" switches and its the same with those, not just the individual "Left Rear" switch.

Hoping for any kind of feedback. Thanks greatly for the help!

Oh also the bags are slam spec in the back and firestone in the front. Switch box is Blitzluft

**octaneman** · 09-20-2009, 10:16 AM

Hi MonteStyle

The first step to take when tackling any type of mechanical or electrical problem is to do some research and familiarize yourself with the system you want to work on. This will require you to read a few articles on electronics and pneumatic systems. Troubleshooting these systems without diagrams is a challenge even for the most seasoned technicians, to the inexperienced, a person attempting to tackle the problem head on without knowledge is only asking for trouble. On this point let me be clear: The risk of personal injury causing irreparable damage to internal systems is extremely high, you will be dealing with pneumatic pressures that exceed 100 psi. So if you any doubts, or don't know what you're doing, it is best that you bring the truck to a qualified technician.

Pneumatic systems work with air pressure that is pumped from the compressor, the bellows on the shock absorber fills up and then the car is raised. Depending on the systems configuration, the most common problem that you will come across is that they leak air due to corroded couplings, cracked lines, or broken internal components. Many times the pressure relief valve gets stuck preventing the system from working properly.

The simplest method in determining where the system leaks is to take any bottle that has a pump spray, fill it with a good amount of soap and water then spray it on every line clamp, check valve, and everywhere where you think it might leak. If it leaks, the soap will make suds pointing you to where the problem is.

The electrical system is a little more of a challenge. Depending on the level of professionalism when the system was installed, you will have to locate and test all switches, fuses, relays,( if applicable) and do a continuity test on all connections to and from the compressor for open or shorted circuits. It is important that if you find the same color coded wire that is hard wired to the fuse box or the entire system, then you will need to determine the polarity of all connections before attempting any wire connections. If any wires are connected to the steering column LEAVE IT ALONE !

Note: THE AIR BAG SYSTEM IS UNDER EXTREME GAS PRESSURE. DEATH OR SERIOUS PERSONAL INJURY CAN RESULT IF THE AIR BAG DEPLOYS PREMATURELY!

Good luck !

post back your findings.

MonteStyle · 09-20-2009, 12:28 PM

Thank you for the response. You are correct that I do have to do alot of reading and research to learn about this system. I'm not working on it alone though, I have a seasoned mechanic that takes all precautions helping me out.

I will take a look at the things you have pointed out!

I hope to get under the truck today to take a look at it. I will post any findings we may have! Thanks again!

09-19-2009, 09:10 PM	#1 (permalink)
MonteStyle Registered User Join Date: Sep 2009 Posts: 2 OS: vista 64	02 GMC Sierra airbag problem Hi, new to forums but I have a lil problem with my airbag suspension. First of all I didn't install this myself. The previous owner did everything to it himself, and have to admit I'm a rookie when it comes to this stuff so I hope that someone can help me out here. First off the compressor. Was working fine for awhile but one day it would not come on. It only chooses to come on when it thinks it should, guessing it detects the PSI in the bags then comes on when needs to. Needless to say, I was driving and started noticing the truck was getting a little to low for my tastes, I switched on the compressor and it would not come on. Turns out I somehow burned the power wire under the truck. Got that fixed and it works now but ever since then it literally needs the truck to be on the ground for the compressor to come on, sometimes thats not even enough. Come back 3 hours later THEN when I flip the switch it comes on. Someone suggested that I might need a new Pressure Sending Unit or something to that effect. Secondly all the switches for the truck were working fine until today when the left rear one don't want to lift up. It will go down just fine, but when I hit it to go up it wont. All the others are fine. Ive tried the "side" and "back" switches and its the same with those, not just the individual "Left Rear" switch. Hoping for any kind of feedback. Thanks greatly for the help! Oh also the bags are slam spec in the back and firestone in the front. Switch box is Blitzluft

09-20-2009, 10:16 AM	#2 (permalink)
octaneman Mentor Home Support, Gearhead Automotive Center Join Date: May 2009 Posts: 544 OS: WINXP	Re: 02 GMC Sierra airbag problem Hi MonteStyle The first step to take when tackling any type of mechanical or electrical problem is to do some research and familiarize yourself with the system you want to work on. This will require you to read a few articles on electronics and pneumatic systems. Troubleshooting these systems without diagrams is a challenge even for the most seasoned technicians, to the inexperienced, a person attempting to tackle the problem head on without knowledge is only asking for trouble. On this point let me be clear: The risk of personal injury causing irreparable damage to internal systems is extremely high, you will be dealing with pneumatic pressures that exceed 100 psi. So if you any doubts, or don't know what you're doing, it is best that you bring the truck to a qualified technician. Pneumatic systems work with air pressure that is pumped from the compressor, the bellows on the shock absorber fills up and then the car is raised. Depending on the systems configuration, the most common problem that you will come across is that they leak air due to corroded couplings, cracked lines, or broken internal components. Many times the pressure relief valve gets stuck preventing the system from working properly. The simplest method in determining where the system leaks is to take any bottle that has a pump spray, fill it with a good amount of soap and water then spray it on every line clamp, check valve, and everywhere where you think it might leak. If it leaks, the soap will make suds pointing you to where the problem is. The electrical system is a little more of a challenge. Depending on the level of professionalism when the system was installed, you will have to locate and test all switches, fuses, relays,( if applicable) and do a continuity test on all connections to and from the compressor for open or shorted circuits. It is important that if you find the same color coded wire that is hard wired to the fuse box or the entire system, then you will need to determine the polarity of all connections before attempting any wire connections. If any wires are connected to the steering column LEAVE IT ALONE ! Note: THE AIR BAG SYSTEM IS UNDER EXTREME GAS PRESSURE. DEATH OR SERIOUS PERSONAL INJURY CAN RESULT IF THE AIR BAG DEPLOYS PREMATURELY! Good luck ! post back your findings. Last edited by octaneman; 09-20-2009 at 10:27 AM.

09-20-2009, 12:28 PM	#3 (permalink)
MonteStyle Registered User Join Date: Sep 2009 Posts: 2 OS: vista 64	Re: 02 GMC Sierra airbag problem Thank you for the response. You are correct that I do have to do alot of reading and research to learn about this system. I'm not working on it alone though, I have a seasoned mechanic that takes all precautions helping me out. I will take a look at the things you have pointed out! I hope to get under the truck today to take a look at it. I will post any findings we may have! Thanks again!