Fule pump signal missing, burnt slot on CEM

frmtaat · Post by **frmtaat** » 05 Mar 2021, 09:03

Hello,

So i still have this intermittent start issue (crank but wont start only if remove battery cable for 30 sec, then fires straight up). Vida says CEM-3A01 Fuel pump signal missing, but the car was actually running while i took the screenshot, so it must be intermittent.
I also noticed a brownish/black burn mark on CEM for fuel pump relay terminal 87 i think (the one on the edge of the CEM, paralell with the edge). I have bench tested and also replaced the fuel pump relay with an another identical one, so i assume its not the relay itself. Do you have any idea how can it relates to my intermittent no start issue if any, why my issue is solved by removing battery cable if it is fuel pump and not control module related and what could cause the burn on CEM?

Thanks in advance!

Mate

(99 S80 non turbo)

Post by **SuperHerman** » 12 Mar 2021, 18:22

Do you have any pictures of the board?

Have you checked the Shunts? You may have a failed one related to the fuel pump circuit.

Post by **RickHaleParker** » 12 Mar 2021, 22:32

frmtaat wrote: ↑05 Mar 2021, 09:03 I also noticed a brownish/black burn mark on CEM for fuel pump relay terminal 87 i think (the one on the edge of the CEM, paralell with the edge).

That could of originated right there where you see it. Oxidation creates resistance. Current through resistance creates heat (P= I² R ).
Have you tried cleaning the edge connector?