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Lou P. master tech
Lou P. master tech, Mercedes Technician
Category: Mercedes
Satisfied Customers: 4087
Experience:  15 years master certified 100% fix rate and have access to factory radio codes, wiring, and instructions.
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Lou. check engine came back secondary air pump. The 03 S55

Customer Question

hello Lou.
check engine came back for the secondary air pump. The 03 S55 compressor.
Question: is there any way to test the relay, or the wiring harness? The pump is good, but it won't turn on.
Submitted: 1 year ago.
Category: Mercedes
Expert:  Lou P. master tech replied 1 year ago.
Hello my name is ***** ***** i will do my best to help you , i strive for EXCELLENT service and nothing less. Hello again. Did you end up replacing anything last time we chatted ?
Customer: replied 1 year ago.

nope. just cleared the code, but it came back. The thing is, when i took out the relay, and put it back in, it clicked. That's why i'd like to test it if it's possible.

Expert:  Lou P. master tech replied 1 year ago.
If it clicked that means the pump should have been on. Did you take out the correct relay ? It was relay "O" wasn't it ?
Customer: replied 1 year ago.

it was N.

Expert:  Lou P. master tech replied 1 year ago.
Right ok. Alright. If you look on the relay you should see the numbers 85-86-87-30 yes ?
Customer: replied 1 year ago.

yes, that's the one

Expert:  Lou P. master tech replied 1 year ago.
Ok if you put a wire where 87and 30 go and touch them together the pump should run. Try that. And I'm talking about inserting the wire into the fuse box where 87 and 30 would plug into. Make sure you quadruple check to make sure it's the correct pins !
Customer: replied 1 year ago.

but the engine has to be cold, right? the ecu controls the air pump....

Expert:  Lou P. master tech replied 1 year ago.
That doesn't matter. When you jump those slots you are actually activating the air pump. YOU are being the relay at this point. The goal is to see if the pump comes on. And it does not matter if you already tested the pump. I want to know if it comes on when jumping the wires.
Expert:  Lou P. master tech replied 1 year ago.
I sent over an offer if you're interested it is up to you
Customer: replied 1 year ago.

i already have your #. no the pump did not come on

Expert:  Lou P. master tech replied 1 year ago.
Ok now unplug the pump and test for power at the plug with the wires jumped still.
Expert:  Lou P. master tech replied 1 year ago.
Forgot you did not accept this cause we did not come to a conclusion. No need to start so many new questions. We Can continue here
Expert:  Lou P. master tech replied 1 year ago.
Glad I could help. Please take a second and click the box and rate my service GOOD OR EXCELLENT SERVICE if you feel I have been helpful and please request me in the future. If you feel I have not been helpful please DO NOT RATE BAD OR POOR AND WASTE YOUR MONEY , I will opt out to see if another expert can provide more or better assistance so you're not wasting your money!!. Thanks for choosing just answer. Lou. also , if you feel i deserve one , BONUSES are GREATLY APPRECIATED ! 😉 Keep in mind then when you rate it does not end our conversation. you can still return here to me for follow up information if needed, Lou.