Post by centennialman on Sept 13, 2006 10:32:18 GMT -6
Credits mostly to cherry2002 for the guts of the following - others helped too, plus the following from aurora2001tan:
EDIT: As recently pointed out, it's possible that the 50A fuse for the AIR pump had blown, or worked itself loose, so you might want to check that first. The fuses are located on the passenger side near the front of the engine compartment. You can do that, or, using a Multimeter, check if there is voltage at the electrical solenoid for the AIR pump, which is described further down in the thread. To me, its about the same amount of effort. If you don't have a multimeter, it's a moot point, although if you are serious about self-maintenance, you really should get one.
As an aside, my car has a Shock Tower Brace installed, so don't get confused as to the large black tube running across the back of the engine.
After the above,First, check to make sure that all vacuum hoses are attached, not broken, cracked, or leaking from their connections. The following PICS will help you figure out where some of the hoses are. If the hoses are all OK, then proceed with the following.
It would be helpful if you have the following tools, hand-made connectors, multimeter, or voltmeter, and 9V battery.
To trouble-shoot the Secondary AIR pump, which is inconveniently located under the drivers side fender, and behind the splash shield:
Locate the AIR pump relay, which on the 3.5L is located on the firewall on the passenger side.
By pressing on the locking tab on the side of the relay, it is easy to remove the bottom connector
Power to the pump is supplied by the vertical pin on the connector - it is always 'hot', so be careful. The bottom horizontal pin connects to the pump, which provides its own ground connection. Using a voltmeter (multimeter, etc), check for 12 volts on the vertical (hot) pin. If no voltage, check the fuse in the fuse box in the engine bay. The map on the bottom of the fuse box cover will indicate which 50amp fuse to check. You do not need to (shouldn't) have the ignition on for this test.
If there is voltage, connect the double ended male connector (as seen in the tools photo) first to the horizontal side, and then to the vertical side (to prevent accidental grounding of the hot lead). This will supply power to the pump. If the pump is OK, you will be able to hear it spin up - it is fairly audible. If the pump is defective, replace by removing the left front wheel, fender liner and disconnecting and unbolting it. It is DIY with a bit of effort.Without having precise knowledge, I am assuming that the AIR pump is a typical vane type, and so long as it spins, the vanes are OK and the mechanism is not jammed. I guess that the vanes will wear out over time, but given the duty cycle of the pump, you would have to have a large number of cold starts for this to happen. The 'pump' is actually a blower, similar to the kind found in a shop vac, except it has two sets of enclosed blades. The newest retrofit has an air intake snorkel designed to take input air from the air box. This should (Hopefully) prevent the air ingestion problem which will ultimately cause your pump and air diverter valves to fail. The blades of the pump are at the bottom. The top portion of the housing encloses the motor.
The blower with re-engineered snorkel:
To trouble shoot the AIR Diverter Valves:
Start with the driver-side valve, and remove the small rubber hose from its plastic connector as seen below - do not remove it from the valve body yet:
Gross as it may sound, it is easy to check if the valve holds vacuum by sucking on the open end of the disconnected tube - clean it first if you like, coat it with Scotch, beer, whatever. Or, if you have 1/8” plastic tubing, use that instead, but you will have to remove the existing tube from the valve body – it should easily pull off.
If the valve holds vacuum, your tongue will stick to the end of the tube, and it will hiss when you release it (the hose, not your tongue). If it doesn't hold vacuum, you will have to replace the valve, or put up with the check engine light until it burns out. The needle nose pliers are very helpful in replacing the vacuum hose onto the plastic connector that you removed it from, but don't do that yet if the valve is OK.
If the driver's side valve is OK, proceed to check the passenger side valve by removing the driver's side vacuum tube (the one you were sucking on) from the valve body. Now, disconnect the corresponding tube from the passenger side valve, and connect the tube that you just removed from the driver side to the fitting on the passenger side valve. Do it this way because: you just cleaned the end of the tube; it is long enough to test using your built-in vacuum, whereas the hose on the passenger side is too short. See pic below. You can see where the L-shaped connector has been removed, and the similar L-shaped connector from the driver's side hose plugged in. Suck away. If it holds vacuum, the valve is OK.
=>
Testing the vacuum Solenoid:
If all of the above tests OK, then test the vacuum solenoid, located under the Engine Sight Cover (cute GM name).
Using the needle nose pliers, simultaneously press in the locking clip and pull the connector from the solenoid. Be gentle!!!!
You can test to see if the solenoid operates by using the two female ended jumpers and a 9V battery - if the solenoid clicks, it's probably OK. You can also verify its correct mechanical function by checking for vacuum on both of the lines connecting the diverter valves. You can only do this on a cold engine for the first 90 seconds, or by opening the solenoid using a battery as above. A vacuum should be present on both Air Diverter Valve vacuum tubes while the engine is running. If you have to use the battery to open the solenoid while the engine is running, BE CAREFUL!!!!!!!!!!!! Actually, be careful whenever the engine is running while you are mucking about under the hood.
If non of the above identifies the problem, then I admit defeat for the time being. Keep in mind that the computer checks correct operation on a random basis, so the check engine light may not extinguish for a while after replacing the broken piece.
Using the above, I discovered that the passenger side Diverter valve was not holding vacuum. Given that it's the most expensive part, figures.
EDIT: As recently pointed out, it's possible that the 50A fuse for the AIR pump had blown, or worked itself loose, so you might want to check that first. The fuses are located on the passenger side near the front of the engine compartment. You can do that, or, using a Multimeter, check if there is voltage at the electrical solenoid for the AIR pump, which is described further down in the thread. To me, its about the same amount of effort. If you don't have a multimeter, it's a moot point, although if you are serious about self-maintenance, you really should get one.
As an aside, my car has a Shock Tower Brace installed, so don't get confused as to the large black tube running across the back of the engine.
Next,FIRST thing to do is tosee if the cheapest part of the system is bad or leaking and that's the Vacuum Control Solenoid.What the write up doesn't have you do is check for vacuum when the car is hot.
1. When hot remove one of the small air divertor valves and hold your finger over the hose for at least 1- 2 minutes. What your checking here for is a slight leak in the solenoid that builds up pressure and causes the valves metal plate inside to flap constantly and soon break. Part cost is $36.00. make sure there is no suction on the valves when the motor is hot and the engine compartment at driving temperature. I'm sure this is why the metal plates break. It will also cause back pressure to run back through the air system and into the air pump!!! You will hear the diff by removing and installing either valve hose.
2. Inspect for an orange color or seepage around all the hoses and the air valves outlets. Of you see any that is because the air system has be taking in water. Also a bad air system that is sucking water will cause a small amount of steam to come out of the Exh. After a cold start up if the pump and at least one valve is functioning.
After the above,
It would be helpful if you have the following tools, hand-made connectors, multimeter, or voltmeter, and 9V battery.
To trouble-shoot the Secondary AIR pump, which is inconveniently located under the drivers side fender, and behind the splash shield:
Locate the AIR pump relay, which on the 3.5L is located on the firewall on the passenger side.
By pressing on the locking tab on the side of the relay, it is easy to remove the bottom connector
Power to the pump is supplied by the vertical pin on the connector - it is always 'hot', so be careful. The bottom horizontal pin connects to the pump, which provides its own ground connection. Using a voltmeter (multimeter, etc), check for 12 volts on the vertical (hot) pin. If no voltage, check the fuse in the fuse box in the engine bay. The map on the bottom of the fuse box cover will indicate which 50amp fuse to check. You do not need to (shouldn't) have the ignition on for this test.
If there is voltage, connect the double ended male connector (as seen in the tools photo) first to the horizontal side, and then to the vertical side (to prevent accidental grounding of the hot lead). This will supply power to the pump. If the pump is OK, you will be able to hear it spin up - it is fairly audible. If the pump is defective, replace by removing the left front wheel, fender liner and disconnecting and unbolting it. It is DIY with a bit of effort.
The blower with re-engineered snorkel:
To trouble shoot the AIR Diverter Valves:
Start with the driver-side valve, and remove the small rubber hose from its plastic connector as seen below - do not remove it from the valve body yet:
Gross as it may sound, it is easy to check if the valve holds vacuum by sucking on the open end of the disconnected tube - clean it first if you like, coat it with Scotch, beer, whatever. Or, if you have 1/8” plastic tubing, use that instead, but you will have to remove the existing tube from the valve body – it should easily pull off.
If the valve holds vacuum, your tongue will stick to the end of the tube, and it will hiss when you release it (the hose, not your tongue). If it doesn't hold vacuum, you will have to replace the valve, or put up with the check engine light until it burns out. The needle nose pliers are very helpful in replacing the vacuum hose onto the plastic connector that you removed it from, but don't do that yet if the valve is OK.
If the driver's side valve is OK, proceed to check the passenger side valve by removing the driver's side vacuum tube (the one you were sucking on) from the valve body. Now, disconnect the corresponding tube from the passenger side valve, and connect the tube that you just removed from the driver side to the fitting on the passenger side valve. Do it this way because: you just cleaned the end of the tube; it is long enough to test using your built-in vacuum, whereas the hose on the passenger side is too short. See pic below. You can see where the L-shaped connector has been removed, and the similar L-shaped connector from the driver's side hose plugged in. Suck away. If it holds vacuum, the valve is OK.
=>
Testing the vacuum Solenoid:
If all of the above tests OK, then test the vacuum solenoid, located under the Engine Sight Cover (cute GM name).
Using the needle nose pliers, simultaneously press in the locking clip and pull the connector from the solenoid. Be gentle!!!!
You can test to see if the solenoid operates by using the two female ended jumpers and a 9V battery - if the solenoid clicks, it's probably OK. You can also verify its correct mechanical function by checking for vacuum on both of the lines connecting the diverter valves. You can only do this on a cold engine for the first 90 seconds, or by opening the solenoid using a battery as above. A vacuum should be present on both Air Diverter Valve vacuum tubes while the engine is running. If you have to use the battery to open the solenoid while the engine is running, BE CAREFUL!!!!!!!!!!!! Actually, be careful whenever the engine is running while you are mucking about under the hood.
If non of the above identifies the problem, then I admit defeat for the time being. Keep in mind that the computer checks correct operation on a random basis, so the check engine light may not extinguish for a while after replacing the broken piece.
Using the above, I discovered that the passenger side Diverter valve was not holding vacuum. Given that it's the most expensive part, figures.