2005 4.3 mpi: beep every 1 minute, fault code 37. How do I proceed?

[MarkSee]

Time to dig into why I'm getting a single buzzer beep once a minute that actually started last year. Just completed all normal servicing engine/drive but did not help. Rinda scanner shows fault code 37 that in Merc manaul #36 shows as "blk psi ckt low". When I look at the specific reading on the scanner, it shows 0 percent no matter what the rmp is. Fault explanation 'block pressure sensor circuit is open', possible root cause of "wiring problem/sensor problem". This is where I get lost as page 3a-24 of manual 36 is for the seawater pump circuit but I'm lost trying to find that sensor on the engine to see if disconnecting it stops the buzzer (if that's even the right thing to be looking for). I also have Merc manual 32 but not finding in that where the sensor is. Note that on the scanner the water temp is fine at 159, has a brand new impeller just installed and new housing last season. Though the boat is 2005 model year, the engine shows as 2004. S/n 0w068186
Where do I go from here?
thanks
Mark

 

[Pete104]

Re: 2005 4.3 mpi: beep every 1 minute, fault code 37. How do I proceed?

Have you tried clearing the code?
The water pressure sensor is threaded into the P/S fluid cooler. It's possible that the ground isn't good.
Or, Merc did have an issue with sensors that were manufactured prior to May 2008. O-ring is missing IN the assembly that allows moisture in.
The code must be cleared when a replacement is installed.

 

[MarkSee]

Re: 2005 4.3 mpi: beep every 1 minute, fault code 37. How do I proceed?

Yes, I did clear the code but it keeps coming back. I did see a sensor at the very back of the engine on the p/s cooler and I disconnected that but the buzzer continued; I was not sure what that sensor was. So if unplugging that sensor still allowed the buzzer to sound, what does that mean and what's next?
Mark

 

[Pete104]

Re: 2005 4.3 mpi: beep every 1 minute, fault code 37. How do I proceed?

Replace it. Unplugging doesn't tell the ECM anything. The Scan tool & sensor is what communicates.
Make sure the oil cooler is grounded. Test clip on B+ & just probe the cooler. You should get a light.

 

[MarkSee]

Re: 2005 4.3 mpi: beep every 1 minute, fault code 37. How do I proceed?

ok; if I do that test I do get a light but in some spots on the metal fitting that screws into the cooler I have to push pretty hard to get the light to come on; other spots on the fitting I just touch lightly and the light comes on. So does that indicate the ground is good and I replace the sending unit? Would I replace the nylon piece of that unit that the wires clip into or the metal fitting that screws into the nipple on the cooler or both?
Mark

 

[Pete104]

Re: 2005 4.3 mpi: beep every 1 minute, fault code 37. How do I proceed?

I would say the ground is fine. Being made out of copper, it's very conductive. You were pushing thru paint that is heavier some places than other.
There is service bulletin on this issue. Not sure when it was published but I want to say '09. Maybe your local dealer will show it to you.
Replace it.

 

[MarkSee]

Re: 2005 4.3 mpi: beep every 1 minute, fault code 37. How do I proceed?

I'll replace it then update the post.
thanks for the help.
Mark

 

[MarkSee]

Re: 2005 4.3 mpi: beep every 1 minute, fault code 37. How do I proceed?

Just replaced the sensor with a new one ($92), ran the boat with no beeps sounding and the code 37 no longer showing on the scanner.
thanks for everyone's help.
Mark