Sensor Power Message??

[rdiesel01]

250XS 0t819117 - Yesterday while going through a long no wake zone I got the message "Sensor Power" on the Smartcraft gauge and the engine wouldn't rev past 590 rpm's. Once or twice the rpm's surged up for a second or two which was followed by a "TPS" error message. I continued on with the other 2 engines and anchored up for a few hours ad hung out. When I go to start the engines the one wouldn't turn over - dead battery. Voltage on the smartcraft with the key on was 12.7 - 12.9 when I tried to crank it ovr it dropped to approx. 9.5. So - do I have a battery issue? An alternator issue? A tps issue? Thanks

[Savage]

I would start by having the battery LOAD tested.

[rdiesel01]

So I have some additional information I hope will help. I put a new battery in and no change - the engine cranks over and tries to fire but it doesn't catch. Next I hooked up a techmate pro and there were 3 fault codes: 123 TPS 1 Range Low - 133 Power 1 Volts (5VDC) Low - 131 Trim Sensor Circuit Low - ????

[lpugh]

Keep in mind a scan tool reports what the ECM thinks is occurring at input and outputs captured within the ECM. Time to put the DVOM to work and actually measure these circuits.
Voltage drop test power and ground circuits to the battery first with a load such as cranking the motor
then test both 5v reference and reference grounds, If voltage is low, start disconnecting sensors one at a time to see if it suddenly comes up to 5v, wiggle test all wiring for effect. Be sure to check the reference grounds as well. Inspect the ECM connectors for water intrusion or corrosion as well as all sensor connectors.
Do not use a test light or analog voltmeter on any of these circuits, Must be a good quality 20 meg ohm, high impedance DVOM
I have noticed that any problems with the reference circuits will set a TPS code first, meaning it probably is not a tps issue.
This is really a job for a experienced Tech, there are many mistake that you could make that could damage the ECM

Have you done any electrical work on the boat recently prior to this occurring?
Is the smart craft reading this motor?
Voltage of 9.5 while the motor is actually cranking is a bit low, but could be normal depending on the battery and if it has good connection measured at the battery

[rdiesel01]

No electrical work at all has been done to this motor. Yes the Smartcraft is reading this motor-while underway it was giving a check engine message as well as a TPS message. "then test both 5v reference and reference grounds" - where are those located? Thanks for the reply

[lpugh]

If the other motors are the same. Switch that ecm to another motor and see if the problem follows the ecm, if so there is your answer. If not take it to a Mecury dealer

[EuropeanAM]

Load test that battery and check the connections.