2003 SAN engine coolant sensor

[lbz99smp]

We're having a problem with our engine coolant sensor in our 2003 SAN.
Hoping someone might have some suggestions.

We have just been through the process of pulling the engine out and putting it back in. Everything seems to be good except the temp sensor

- Currently the large engine warning light is coming on before startup and staying on throughout running. Digital read out is also stating to see dealer 'Engine coolant sensor'
Analog gauge is working fine.

- we have water tested the boat the other day and it seemed to run fine. Temperature was in the range of 150-170 through out water test.
- I’ve checked all of the plugs into the faria gateway and all seem fine.
- Temp sensor plug seems fine.
- Engine light and message continues to appear when sensor is disconnected.

not sure what to check next....... could it infact be the sensor that is faulty? i'm finding this hard to believe when the warning still comes up when it is disconnected. Could the issue be back at the faria gateway?

I've attached a pic of where I understand the sensor to be.

not sure what to check next……….

Any suggestions or help would be appreciated.

[AirTool]

RE: 2003 SAN engine coolant sensor

The "temperature sensor" varies in resistance as a function of temperature. It has a two wire connector that loops with the ECM. If you disconnect it, the MIL light should come on. If the sensor is not working properly, likely the MIL light will come on.

The first thing you need to do is check the resistance of the element across the two connector pins. Here is an "approximate" chart to get you started. It is not specifically for this application ...but similar. No matter, you should not measure infinite ohms at ambient temperature. If you do, the sensor is bad. Check for something similar to these values. If, by chance, there is only one pin, measure resistance from the pin to the brass body.

Do this...and report back.

177 ohms @ 212 deg. F. or 100 deg. C.
241 ohms @ 194 deg. F. or 90 deg. C.
332 ohms @ 176 deg. F. or 80 deg. C.
467 ohms @ 158 deg. F. or 70 deg. C.
667 ohms @ 140 deg. F. or 60 deg. C.
973 ohms @ 122 deg. F. or 50 deg. C.
1188 ohms @ 113 deg. F. or45 deg. C.
1459 ohms @ 104 deg. F. or 40 deg. C.
1802 ohms @ 95 deg. F. or 35 deg. C.
2238 ohms @ 86 deg. F. or 30 deg. C.
2796 ohms @ 77 deg. F. or 25 deg. C.

[DanielC]

RE: 2003 SAN engine coolant sensor

Many cars have two engine coolant sensors. One is for the temp gauge, and the other is for the computer. I believe marine engines are the same. My GT-40 has two temp senders.

[AirTool]

Re: RE: 2003 SAN engine coolant sensor

Many cars have two engine coolant sensors. One is for the temp gauge, and the other is for the computer. I believe marine engines are the same. My GT-40 has two temp senders.

The exploded view shows both devices:

29 for the guage (one wire)

33 for the ECM (two wire)

[lbz99smp]

Airtool, thanks for the info.

The sensor has two pins. I checked the resistance accross the pins and the results where similar to the figures you have given. I also removed the sensor and checked the reistance while heating the sensor up close to a light bulb. The closer to the bulb the lower the resitance and hotter the sensor was so based on this I am assuming the sensor is in working order.

I have also checked to see if the wires are continous to the ECM. PCM have color coded and number labled the wires which makes it a little easier. They are continous to the ECM.

I am also getting 5v accross the wires coming into the sesor once the ignition is on.

All other engine information appears to be fine on the gauges. So I'm thinkinh the connection from the gateway box to the guages is ok.

Only other thing i can think of is the issue may be from the ECM to the faria gateway...... not to sure though.

Any ideas.

[AirTool]

I don't think this will help....but disconnect the battery for a few minutes and reconnect to see if the code clears. On OBD1 and maybe OBD2 autos, I remember this code to clear itself....but the boat ECM may be different. Maybe the code has to be cleared with a code reader...but I would hope not.

Also make sure the female pins in the pigtail are all the way to the end and are actually connecting to the sensor.

When you're running the engine and disconnect the plug from the sensor, does the idle speed change and then correct? My experience is when everything is proper, disconnecting the plug speeds up the engine momentarily and then it returns to normal. Reconnecting the plug doesn't yield the same result. Try that and see what happens. If the speed changes, that would tell me that ecm communications are okay. I don't think it checks the ECM to gateway communication.

I'll keep thinking about this one.