Air pump on a 99 Tahoe

Discussion in 'Tech Info' started by 99whitehoe, Jun 13, 2011.

Car Parts
  1. 99whitehoe

    99whitehoe TYF Newbie

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    I tried using the search option but couldn't find what I was looking for so here goes.

    My air pump constantly runs in my truck no matter if the motor is running or not. I have to take the positive battery cable off to make sure my battery does not run down. Someone said I should try to reset the air pump. How do I do that?
     
  2. SunlitComet

    SunlitComet OBS Jedi-Do Good

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    :welcome:

    You don't. The electric system is controlled by a relay that is triggered by the drivetrain computer(PCM). Your relay may be shorted out or your pcm might be faulty or is commanding it on all the time for a reason. At any rate the power feed to the pump thru relay control should be the AUX B Maxi fuse under the hood if you want to disable it until the primary problem is solved. Relay is in the same electrical box. Are you not showing any other problems or warning lights? Can you test your relay?




    The electric motor Secondary Air Injection (AIR) system is used on the 5.7L to reduce Carbon Monoxide (CO) and Hydrocarbons (HC) .

    The AIR system adds air (oxygen) to the exhaust manifold to continue oxidation after the exhaust gasses have left the combustion chamber. The heat from this reaction brings the catalytic converter up to operating temperature taster when the engine is cold. This system consists of an electric AIR pump, check valves, and necessary plumbing.






    An electric motor AIR pump supplies filtered air from the air intake system to the AIR injection pipes.

    The check valves, on the AIR injection pipes, prevent backflow of exhaust gasses in the AIR pump.

    When the engine is started with a coolant temperature above approximately 15°C (45°F) or if the fuel system is in the Decel Mode, the VCM energizes the AIR relay. The AIR relay then energizes the AIR clutch, which directs air into the exhaust manifold ports.

    The control module may turn the AIR pump OFF when any of the following conditions occur:

    • The system is in the Closed Loop mode
    • Any DTCs are set
    • The system is in Power Enrichment mode for more than a short period of time
    • Low manifold pressure (over run)
    • Quick vacuum rise (rapid decel)
     
    Last edited: Jun 13, 2011
  3. 99whitehoe

    99whitehoe TYF Newbie

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    Thanks for the info. I did have a blown fuse at first and replaced it and noticed the pump running constantly. I disconnected the positive terminal on the battery to look for pinched wires or anything obvious. Didn't see anything so I connected my positive and heard no noise. Thought it was funny but figured maybe it was a fluke thing and tried to fire it up. Nothing...fuel pump not coming on. Same fuse blown again. Took a spare and plugged it in and it blew it instantly. Took the fuel relay out and tapped it and put the fuse back in without the relay plugged back in. No blown fuse. Went to plug the relay back in assuming it would probably blow the fuse and it didn't.

    Unplugged the relay and tried to start it up and it fired up. I couldnt figure out how the truck fired up with out the relay plugged in. Maybe something else shorted out?? Once I figure it out I'll post the results just in case someone else has this same issue in the future.

    Sorry for the long post... Oh and thanks for the welcome!! Didn't find a newbie introduction section.
     
  4. SunlitComet

    SunlitComet OBS Jedi-Do Good

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    which fuse was this that was blowing. How did you get to the fuel pump relay from the air pump relay. Maybe I missed something here.

    BTW we users make your first thread or post the introduction section usually.

    Don't fret over long posts the more info the better.
     
  5. 99whitehoe

    99whitehoe TYF Newbie

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    Well when I noticed the air pump staying on all the time I also noticed the fuel pump itself sounded like it never would shut off. So I disconnected the battery too look for something obvious which I didn't see. I went to hook the batt back up and now had nothing. No air pump making noise no fuel pump....nothing. So I began to look around at different things like fuses and noticed the fuel pump fuse(red 30 amp) was blown. Once I saw that then I got to thinking that maybe the fuel pump relay was stuck causing the air pump to run constantly. So I unplugged the relay for the fuel pump assuming that the fuel pump would not come on and if my assumption was correct neither would the air pump. Unplugged the relay and turned on the key and the fuel pump and air pump came on just like before..even with the fuel pump relay not installed. Then I plugged the relay back in thinking that the fuse that had previously blew would do it again. Well it didn't. I'm gonna pull the distributor to see if any wires behind the motor may be shorted or something. If not I guess I'll take it to a shop since I'm out of ideas.. Some reason I'm thinking I have a wire broke or shorted out. Gonna be something simple I know!
     
  6. SunlitComet

    SunlitComet OBS Jedi-Do Good

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    I would check underneath the engine bay fuse/relay box for a broken circuit
     
  7. 99whitehoe

    99whitehoe TYF Newbie

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    Found what the problem was. I had an O2 sensor wire shorted to my oil sending unit wires.. Don't ask me how they got together but thats what it was. I cut them and rewired it and everything seems to be good to go.
     
  8. msark

    msark Member

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    I just bought a 97 Tahoe. Inspecting it today and found that my A.I.R. relay is not installed.... Do I need to put it in?? Also found the Brake Lamp Relay missing as well as the 30A Stop Hazard fuse... Help??
     
  9. BurlingameDad

    BurlingameDad TYF Newbie

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    I have a 1999 K1500 Suburban, and while the inside-engine fuse/relay box has a space for an "A.I.R. Relay (Mark Eng)" relay, indicated by the diagram, but in fact that relay is not used -- if you look at the spot there are no electrical connections for a relay there. So, I'm guessing that the PCM controls the on/off operation of the Secondary Air Injection (eg: smog) pump. IMG_9646.JPG
     
  10. drakon543

    drakon543 Full Access Member

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    first up feel free to post a new thread with questions regarding your vehicle. please dont resurrect dead threads.
    in response to your post its also possible you just dont have the smog pump. i wasn't aware they even came with them but it could have just been a California emissions thing. alot of vehicles have 2 different emissions variations based on regular federal requirements and California regulations.
     
    wjburken likes this.

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