Temperature Gauge not working - Volvo Penta 5.7 GI-E

[spomey]

I want to thank everyone who helped, especially @alldodge, who realized I was mixing things up. I replaced the sending unit, and it's working fine now!

Your mixing Temp sender and temp switch
The gauge at the helm uses the sender in your pic and goes direct to the gauge, it does not go to the ECM

Your motor also has a 2 pin temp switch that goes to your ECM (assuming J2-7). The temp switch closes when the temp gets to hot and sounds the alarm.

The temp sender and the gauge does not talk to the ECM, it's only there as a visual indication for the driver

I have a 99 5.7 GSI and I am having the same issue temp gage is pegged at key on/power. I also Have tried everything that I could think of, new gage, new temp switch checked wiring with no changes. this could be the issue. I "found" a two wire connector behind the #1 fuel pump and filter, under the coolant hoses and in front of the circuit breaker box (if that makes sense). looking at the engine its in the front left of the engine buried under the wires hoses and fuel stuff.

the connector is round with two wires white/blue strip and grey and fits onto a round connector with a flat edge on one side (see pictures).
what is this plug I cant find these colors in any schematics or wire color charts that I can find.

 

[alldodge]

Moved you to your own thread

That is a White with Blue stripe (Wht/Blu) and connects to a knock sensor (if installed). It is the item just in the pic bottom right



The gauge sensor is a single wire sensor on the thermostat housing. The single Tan colored wire connects to a sensor which changes resistance between 240 ohms to 33 ohms (hot).

Disconnect this wire and what happens to the gauge reading

 

[gilsaraiva]

I have a 99 5.7 GSI and I am having the same issue temp gage is pegged at key on/power. I also Have tried everything that I could think of, new gage, new temp switch checked wiring with no changes. this could be the issue. I "found" a two wire connector behind the #1 fuel pump and filter, under the coolant hoses and in front of the circuit breaker box (if that makes sense). looking at the engine its in the front left of the engine buried under the wires hoses and fuel stuff.

the connector is round with two wires white/blue strip and grey and fits onto a round connector with a flat edge on one side (see pictures).
what is this plug I cant find these colors in any schematics or wire color charts that I can find.View attachment 403302View attachment 403303

Hi, I might be wrong but your connector looks like the Trimm sender on my boat.

 

[spomey]

Hi, I might be wrong but your connector looks like the Trimm sender on my boat.

my trim gage seems to work correctly and I cannot find anything to hook this two wire connector to.

 

[spomey]

Moved you to your own thread

That is a White with Blue stripe (Wht/Blu) and connects to a knock sensor (if installed). It is the item just in the pic bottom right

View attachment 403304

The gauge sensor is a single wire sensor on the thermostat housing. The single Tan colored wire connects to a sensor which changes resistance between 240 ohms to 33 ohms (hot).

Disconnect this wire and what happens to the gauge reading

lets see..I will add pictures of what I think you are saying. the knock sensor is in the photo and uses a blue / black wire

the thermostat housing has a sensor in it but it has two wires I cant remember and I cant find a picture of them but if I remember correctly one was black and the other white and blue (neither were tan). it had a two wire oval connector. plugged in and unplugged did not affect the temp gage.
my boat is a 99 chris craft 230 with a GSI 5.7 volvo penta duo prop setup. I cant help but think these wires have something to do with the temp reading but it just doesnt make sense.

I also have this single black and white wire on top of the intake manifold with a female blade connecto on it that I cnannot find a home for.

 

[spomey]

Moved you to your own thread

That is a White with Blue stripe (Wht/Blu) and connects to a knock sensor (if installed). It is the item just in the pic bottom right

View attachment 403304

The gauge sensor is a single wire sensor on the thermostat housing. The single Tan colored wire connects to a sensor which changes resistance between 240 ohms to 33 ohms (hot).

Disconnect this wire and what happens to the gauge reading

lets see..I will add pictures of what I think you are saying. the knock sensor is in the photo and uses a blue / black wireView attachment 403424

the thermostat housing has a sensor in it as seen in this picture but it has two wires

Moved you to your own thread

That is a White with Blue stripe (Wht/Blu) and connects to a knock sensor (if installed). It is the item just in the pic bottom right

View attachment 403304

The gauge sensor is a single wire sensor on the thermostat housing. The single Tan colored wire connects to a sensor which changes resistance between 240 ohms to 33 ohms (hot).

Disconnect this wire and what happens to the gauge reading

could I get a full picture of this schematic? I cant seem to find it in the electrical section

 

[alldodge]

Yes first pic is knock sensor item 12

Item 13 is knock sensor 2 and this is "IF" installed. The connector has the White/Blue but diagram shows a Black and yours has Gray.

The White/Black connector is unknown to me and doesn't show up in the diagram

Item 17 is the Engine Coolant Temp sensor and goes to the ECM.

Item 23 list as an inductor and don't know what that would be other then it is most likely the manifold air temp because another motor in manual using the same ECM and same pin location list it as such

I have a manual and don't know where it is on line other then through VP