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booneylander

More SAI woes, no power to pump.

4 posts in this topic

Good morning!

So one of my 451s had the check engine light come on. Reading the code the issue was "Fault in secondary air injection system". I couldn't hear the pump go on startup, so it made sense.

I tried connecting the plug to a known good SAI pump and tried activating the system through DAS. I heard relays click in the area of the SAM, and could hear the changover valve clicking away, but the pump didn't come on. I tried again, this time with a voltmeter connected to the plug, and got no voltage on the plug while running the pump in DAS. 

I went through all the fuses and they all appear to be good. I can hear a relay going when DAS switches on the pump, but I'm not sure if it might be another relay for something else going. 

I'm having a real hard time figuring out which relay might control the SAI pump, to try and swap it out for a test. I'm also having a heck of a time trying to figure out which wires to check continuity on at the SAM to see if I'm getting voltage on that end but just experiencing a broken wire between there and the SAI pump. 

So if anyone has any ideas please post them up.

Sean

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Are you testing the SAI loose or attached to the car? Could it be something simple like the casing of the SAI needs to ground to the chassis?

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I tested the original SAI still in place using DAS. I tried using the known-good pump "loose" though it was touching the frame. I measured the ground from the pin in the plug to chassis and got no resistance. The SAI pump is in a plastic case and isolated on rubber mounts so I would be really surprised if it needs to be grounded to the chassis. When I bench-tested the known good pump I just connected the power to either of the terminals and it fired up (no need to ground the chassis).

This one's really annoying me. I can't figure out what to test from here. It's gotta be an issue with either the power lead between the SAI relay to the pump (tested the plug and got about 6Mohm to ground... which come to think of it, should be an open circuit when the pump is not in use). I just wish I knew what wire to connect to on the SAM or relay block to figure out resistance between that and the plug.

I just hope that the SAM hasn't gotten fried or something. I have a spare SAM but I'm nervous about swapping it out and messing up the mileage on the cluster.

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Posted (edited) · Report post

Well I figured this one out.

It was the fuse for the SAI in the passenger footwell by the battery. Never thought to look there, assumed all the fuses would be in or around the fuse box. Silly me.

It didn't even look burnt but the multimeter told the whole story.

Also, the SAI pump was seized. Which is why the fuse blew in the first place.

Replaced the fuse, replaced the pump, all good to go now.

 

 

 

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Edited by booneylander
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