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Secondary Air Pump question
07-27-2011, 05:10 PM
Ok So my check engine light came on & it was the Air pump. Picked up a used one tested it on my bench, worked great. So I installed it, cleared the error code and was happy. A week later my light came back on, same thing air pump. So I put 12v on the pump and it works fine. Light bulb goes off in my head, I never checked the maxi fuse. So sure enough the 30 amp fuse is blown. No worries I have one & put it in. Fired the truck up and don't hear/feel the pump running. So I check the fuse it's still good, check the pump it still works when I put 12V on it. SO my question is: is the secondary air pump supposed to run all the time or only run when the engine is cold? As my car was hot when I was testing it.
07-27-2011, 06:49 PM
The Secondary Air Injection (AIR) System is designed to lower exhaust emission levels during a cold or warm start. The AIR pump is timed to remain ON for approximately one minute after the engine is started. If the pump is not coming on check the air pump relay either in the electrical center or attached to wiring harness. If the old pump blew the fuse due to excessive current draw the relay contacts may have been burnt before the fue finally blew. What year is your Jimmy? I can provide more accurate information and a schematic if it would help.
07-27-2011, 07:21 PM
Thanks for the reply, it is a 2001 GMC Jimmy SLE. I didn't think to check the relay. does the pump turn on when I turn the key to the on position or do I actually have to start the truck for it to come on (I tried it both ways and it wasn't comming on). Will I be able to tell just by looking at the relay if it is bad?
07-27-2011, 07:53 PM
The truck needs to be running. Locate the relay, it appears to be toward the front of the right fender near the battery. There should be power one of the red wires and the pink wire at the relay with the key in run. If you jump the 2 red wires the pump should run. If you can't see the wires look at the diagram on the relay and jump the switch portion. Usually 87 and 30 diagonal from each other. With a test light connected to power, backprobe the brown wire with the test light and start the truck. The light should illuminate. That will test the PCM control circuit. If all of these tests are good, the relay is bad. Notice there are other fuses to check also. You may find an identical relay for another circuit to swap for a test.
If the pump does not run with the relay jumped, check ground 100, near bottom of radiator.
07-27-2011, 08:04 PM
Thanks Procaddy, I'll test it when I get a chance.
07-28-2011, 07:03 AM
"If the pump does not run with the relay jumped, check ground 100, near bottom of radiator. "
Thanks, I'll check the ground out as well, is that on the battery side of the truck and is it accesable from under the hood or under the truck?
07-28-2011, 12:43 PM
You're welcome. I hope I can help out. G100 is number 5 in this illustration. Looks to be under the right headlamp area. May be easier to get to from the bottom. It runs with the forward lamp harness.
08-03-2011, 06:34 PM
Thanks for the help guys! It was a bad ground, both grounds on the front were pretty bad. I hit them with some sand paper & cleaned them both up while I was there. Air pump works like a charm now.
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