Diacom Scan Codes

[JCJ]

1999 Merc. Optimax (ser. #0G886121) -

I had a check engine light come on (no horn), and just used the Diacom software to read the fault code(s). The codes are:

Injector 5 (active code)
RPM Limit (active code)

Anyone know what this is trying to tell me :)? I'm trying to understand if this means a fuel or air injector??? I have no idea what the RPM limit fault code would be related to??? Both codes were pulled with the engine idling, so not high RPM's. Also, I ohmed both the #5 fuel and air injector and they read the same as all my other ones. In addition, I cleaned the connectors with contact cleaner. Fault codes still there.

[Rick H]

Make sure the software is up to date. There was a recent update FYI

[JCJ]

Verified the software is updated. The diacom software/cable/harness is all brand new. I just received it yesterday, so trying it out today :). Still learning how to use it.

[EuropeanAM]

Normally injector is FUEL (unless Direct or Air are specified).

Normally caused by corrosion or dirty connection at the injector.

[JCJ]

Thanks Don. Any ideas what the "RPM Limit" fault means?

[lpugh]

also ohm test connector pin to metal base for short to ground, should be open circuits

[EuropeanAM]

Thanks Don. Any ideas what the "RPM Limit" fault means?

"Engine RPM's exceeded the pre-programmed Maximum RPM's for the given engine conditions".

[JCJ]

Hey ya'll...

Just wanted to circle back and share that I got this problem figured out. It ended up being my #5 air/direct injector. The way I was able to determine that was by running the individual test with the Rinda software. Anytime I'd run the test on that #5 direct injector, my check engine light would light up. I swapped it with my #3, and the problem moved to the #3 injector. I've got another one ordered, and hoping that once I get it in there, the "RPM limit" fault goes away as well. I'm assuming those two faults are related because they always pop up at the exact same time. What I don't understand though, is that it appeared this injector was ok, because I could disconnect it with the motor running, and the motor would bog down / run worse. When I'd plug it back in, you'd hear the motor ramp up and start running normal again. I guess there must be something electrically going on with it that the ECM doesn't like??? Anyways, I appreciate everyone that responded to my questions and helped get me going in the right direction.

Also I wanted to let anyone out there know you can "rent" the Rinda software tool, instead of having to purchase. If you haven't priced them, they're about $600. After contemplating buying one (thinking that it may pay for itself quickly after a couple of trips to a service center), I discovered people renting them out for about $50/week (along with a refundable security deposit). In addition, you can extend the rental out daily or weekly (if needed) for a small fee. Anyways, I felt this was a better alternative for me to take. So far I'm very satisfied with the results, and renting it allowed me to determine if it was something I'd actually like before spending a fairly large sum of money.

[JOE54]

aaaaaahhhh rentals now cool deal , wondered when those would show up