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STLNLUV · 08-31-2014, 12:06 PM

I have a 2006 CAT C9. Coolant in surge tank appears to leak so I thought I'd reseal the "Mini-Tek" Low coolant sensor.

After resealing sensor threads (sensor probe is clean) I get a Code #62. Plenty of CAT approved coolant. Must have a bad sensor so I buy a new sensor and install it and have the same code #62. Drain coolant in surge tank and add new 50/50 coolant mix with distilled water. Still have code. Searched internet for 8 hours+ but could not find instructions on how to test sensor, thinking the new sensor may be bad. Checked connector and I am getting +5.1VDC and ground from ECM. The signal pins have a floating voltage so I know they are connected. I doubt the connector went bad.

Has anyone shorted pin C to pin D to simulate to the ECM that liquid is there? I'm afraid to harm ECM.
Anyone else have this problem and what was their solution?
Any way to test sensor outside the tank with resistance readings?

I appreciate any help. When you get this error the ECM reduces power to the C9 to protect it. A real *itch when driving in the mountains

stuhly · 08-31-2014, 12:40 PM

On my OTR trucks, whenever a sensor threw a code, if it was a two wire sensor I would just snap a scotch lock on the wires. That way it showed full.

krivanj · 08-31-2014, 02:35 PM

Could you have sealed the sensor so that the threads are not grounded in the threaded hole? Maybe the sensor needs that ground connection.

STLNLUV · 08-31-2014, 02:41 PM

Quote:

Originally Posted by krivanj

Could you have sealed the sensor so that the threads are not grounded in the threaded hole? Maybe the sensor needs that ground connection.

Good thought, except the surge tank (overflow) is plastic and the sensor has its own ground wire. Thanks

DieselTech39 · 08-31-2014, 02:53 PM

Just a thought....Disconnect the battery for 15 - 20 minutes and reconnect....should clear the code and then see if it shows again.

STLNLUV · 08-31-2014, 09:15 PM

Quote:

Originally Posted by DieselTech39

Just a thought....Disconnect the battery for 15 - 20 minutes and reconnect....should clear the code and then see if it shows again.

Good Idea

I guess I don't know my coach as well as I thought. I disconnected the POSITIVE lead from the chassis batteries, turned the chassis battery switch to OFF, then to check, I turned the ignition switch ON and still had power

.

It's dark now but tomorrow will try to find out where the chassis power is coming from. Could it be a stuck Big Boy relay? Thanks for the suggestion.

Thank goodness this failure is now, while at home base. Was leaving tomorrow for 4 months on the road. A little delay won't hurt anything.

STLNLUV · 09-02-2014, 11:31 AM

The check engine light no longer comes on while driving and the engine is at full power. Like "stuhly" said, it needed to be cleared from memory by disconnecting the 12 VDC to the ECM. CAT tech told me that it would also clear after driving. Thanks again "stuhly"