air pump relay blows

kenzoil

Active Member
Does anyone have an idea what is causing my air pump relay to blow every 3 to 6 months? (the one under driver seat on chassis frame) Have replaced it 5 times since I owned it, less than 2 years. I have a 2008 trailblazer L6. I have used NAPA brand, Omni brand, GM brand, makes no difference. Thanks for any help.
 

Mounce

Well-Known Member
Air pump pulling more amps than the relay is rated for? Would figure the fuse would be rated lower than the relay however I'm very unfamiliar with the SAIS.
 

Mooseman

Moderator
You mean the relay in the fuse box? That is very unusual. One would think the fuse would blow first like @Mounce said. It is a very failure prone useless system and why we recommend it be deleted and the codes for it tuned out.
 

budwich

Well-Known Member
what do you mean ... "relay to blow every 3 to 6 months ".... what is "blowing" .... the coil or the contacts? or are you just saying the relay no longer works? IF its the contacts, then your pump potentially has an issue drawing too many amps. IF its the coil, then the relay or its socket might be having an issue although if the contacts are over heating because of motor draw then potential enough heat may be causing issues with the coil.
 
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kenzoil

Active Member
the relay stops working, therefore the pump does not turn on, throwing a check engine light and code. It is the relay attached to the chassis, underneath the vehicle. Located in area of drivers side compartment. When the pump works, it sounds fine, and remains on for the required 5 seconds.
There is no water in the pump lines, and the air injection valve has been replaced.
 
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kenzoil

Active Member
I should also say, when I replaced the relay, there are no physical signs of wear on the contacts.
 

budwich

Well-Known Member
the relay stops working, therefore the pump does not turn on, throwing a check engine light and code. It is the relay attached to the chassis, underneath the vehicle. Located in area of drivers side compartment. When the pump works, it sounds fine, and remains on for the required 5 seconds.
There is no water in the pump lines, and the air injection valve has been replaced.
then you actually do not know what is wrong since you did not electrically check the relay. Replacing it could just mean that there was a poor contact in the box and that the replacement "improved" that contact for a "bit" and then eventually the same situation returns. You need to check the old relay electrically (measuring the resistance of the coil, then also operating it, if possible and then checking the contunuity of the contacts thereafter).... my guess is that the relay is actually good and you have problems elsewhere... poor connections in the fuse box or possibly along the wire route to the motor.
 
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kenzoil

Active Member
Is it possible to walk me through how to check the relay? Also, I had the exact same issues on my 2007 trailblazer for many years before I sold it.
 

Mooseman

Moderator
You mean the relay in the fuse box? That is very unusual. One would think the fuse would blow first like @Mounce said. It is a very failure prone useless system and why we recommend it be deleted and the codes for it tuned out.
Like I said, just delete it. Apart from that relay, the valve on the head is also failure prone. A block off plate is available from 2002 models cheap from the dealer (part #12574378) or a junker in a pick-n-pull and the tune is available for $99 from @limequat at lime-swap.com. And get some performance enhancements at the same time. Only down side is that the truck will be down for a few days while the PCM is out to get tuned.

 

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