Temp Gauge or Sending Unit?

[Wingnut95]

Hi Wingers
I have a '95 SE GL1500 and the temp gauge stopped working over the winter (parked). Looking for some direction on how I determine if it's the sending unit or the gauge that's gone before I take it all apart. I've checked and both fans come on when it heats up, but the gauge doesn't budge. Any instructions on how I might test both would greatly help. I'm mechanically inclined, but terrible when it comes to electrical stuff.

I've noticed a bit of antifreeze after riding it, but not sure if that's coming from the overflow or a leak.

I've searched the Forums and haven't seen anything on testing. My apologies if I've overlooked it.

Thanks,

[Fitz]

Find the sending unit on engine. There may be a separate one for fan. Usually the gauge one only has one wire. Unhook the wire and( with key on run) ground to engine. The gauge should slowly go to hot. The sender works by varying the resistance to ground as it gets hotter. By just grounding the wire, it just thinks it's real hot!

[bellboy40]

Does the fuel gauge work? They both get power from the same relay (#3 tail/main relay). If so, then you will need to do some checking on the connectors to the sensor. The easy one to get to is under the right fairing pocket. It is C55, a 13 pin white connector. The green/blue wire is the one going from the sensor to the gauge.
C22 is a 6 pin red connector over the fans. The green/blue wire in it also. You will have to take off some fairing parts to get to it.
The coolant sensor for the gauge is mounted on the thermostat housing and is hard to get to.

Maybe you will get lucky and find the relay bad or one of those connectors has some corrosion.
Good luck.

[Wingnut95]

The fuel gauge does work so I’ll check the relay under pocket first. Do I ground it with key on to see if I get a response or use a meter to determine a response on the meter for the relay?

[bellboy40]

On the C55 connector, ground the green/blue wire, and with the switch turned on, see if the gauge goes up toward hot. I'm not sure if the side you want is male or female but whichever one goes toward the gauge is the side you want. It won't hurt if you ground the side toward the sensor.

[Wingnut95]

Thanks,

I'll let you know how I make out.

[Wingnut95]

No relays under front right pocket, on junction connectors. Did find 2 relays under front lower cover. Are those the ones you are referring to?

[bellboy40]

Not relays. It is connectors I was referring to. That last picture above looks like the right place. Was that taken under the right side pocket? The connector in question there is the white one with 13 pins. Ground the green/blue wire and see if your gauge goes to hot.

[Wingnut95]

Yes, those are connectors under right pocket. Didn’t see a green blue but I’ll look closer tomorrow and give it a shot. Thanks for your ongoing support. Much appreciated.

[bellboy40]

Here is the wiring diagram for the instrument gauges. I don't know if you have this or not but it will be a big help in trying to find the problem with that temp gauge.

GL1500 instrument gauges diagram

[Wingnut95]

Awesome! I was searching online last night for one of these diagrams.

Thank you! This is such a great online community.

[Wingnut95]

I have been able to confirm that the gauge is working
Can someone confirm if access to the sending unit is behind the fan on the left side?

[MikeB]

There is a Coolant Temp Sensor on the right intake manifold. And a Sending Unit on the Thermostat Housing.

This is #23. I'm not sure which one is the correct unit.

[bellboy40]

Here is the relevant page from the Honda service manual on removing that sender unit. Yes, you will need to remove the left side fan to get to it.

Temp gauge sender removal

[Wingnut95]

Thanks to your help I’ve identified the sending unit as the problem, and where to locate it. Parts on order and hope that this fixes the issues.

This is a fantastic community of Wingers and I appreciate the assistance. Not easy caring for a 26 year old bike, but together we can.

Thank You!

[MikeB]

Great job Wingnut95.