PCM is not turning on air pump

Tiny
OSTER
  • MEMBER
  • 2005 CHEVROLET TRAILBLAZER
  • 4.2L
  • 6 CYL
  • 4WD
  • AUTOMATIC
So I have replaced my pump and check valve since I had the P0410 error code. I wanted to maker sure everything was new even though the check valve I had still worked. The pump was full over water.

When I replaced both of these the error was still popping up. I checked my relay and found that it did not work either. I got a new one and thought that cleared up all my issues. Since I was still getting error I checked fuses nothing blown, I looked at the wiring diagram and started testing every thing.

I tested the constant powered line to the relay number 30 got power so I knew that worked.

I tested the RUN/START wire from the fuse 54 to 86 on the pump relay which also controls the check valve relay. Since the check valve works ( I can hear it when I take of the hose open and close) I assumed this worked but tested it anyways. When I checked I got power.

I then tested the power from the pump relay 87 and got power from the connector that power the pump( I had to replace the connector since the old one was badly corroded).

Then there is one last one which is 85 on the pump relay. This one connects to the PCM. So My question is after I checked all the wiring, and individually checked all the parts why does my check valve work, but my pump is not blowing or sucking air through the hoses? I checked the power from the PCM and I didn't get anything which means the PCM never closed the relay to send power to the pumps relay.
Wednesday, October 7th, 2015 AT 8:37 PM

1 Reply

Tiny
CARADIODOC
  • MECHANIC
  • 33,742 POSTS
A friend had the same vehicle with the same problem. He went through four or five pumps, but his failed when the water inside froze. The last pump was from the manufacturer and it has been working fine for about a year.
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Wednesday, October 7th, 2015 AT 8:56 PM

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