98 Std Intermittent Temp Light

[spaldingrb]

Believe me - I have read the related articles on the flickering temp light issue on 97-99 models. After 52k miles my bike has this issue. I have just two questions;

1. This "Temperature Indicator Unit" seems to be out of stock just about everywhere I look. Anyone have an Idea where one can be found?

2. I've also read about replacing the Thermal Unit Sensor with a later model (2000), since it has the internal switch, and then jumper the connection at the Temperature Indicator Unit. Does anyone have the step-by-step instructions for completing this mod?

Thanks in advance...

[sandy]

I'd be interested in this mod myself. Temp light has flickered for near 10 years now. About time I fixed it.

[F6Dave]

I upgraded mine several years ago.  Here is my description, which I emailed to another member last year:

It's been a few years since I did this, but here's what I remember.  The new sensor/switch has the same threads as the old sensor, so it fits fine.  The connector is different (one was a bullet, the other a spade maybe) so you need to make an adapter or replace the one on the wiring harness.
 
The indicator unit reads the voltage from the old sensor, and switches the temp light on at some point.  As I remember it has 4 contacts:  hot/ground/wire from sensor/wire to temp light.  Since the new sensor/switch combines the sensing function with the temp light switching function, the indicator is not needed.  You only need to bridge that sensor/switch wire to the temp light wire.  I did this by making a jumper between those 2 contacts in the connector for the old indicator unit.  The other 2 (hot & ground) are no longer needed.  If you compare wiring diagrams for both versions of the Valkyrie you can see this is what Honda did, and how simple the change really was.

[indybobm]

Sandy, I think this will help.

Here is how I check the operation of the Temperature Indicator Unit and the Coolant Light on a 1997 to 1999 Valkyrie Standard or Tourer

How the light works. The 97-99 Valkyrie Standards and Tourers have a Thermo Sensor on the thermostat housing. The Thermo Sensor has a wire that connects it to the 2P connector on the Temperature Indicator Unit behind the left side cover and overflow tank.
The Thermo Sensor offers a variable resistance to the Temperature Indicator Unit depending on the temperature of the coolant. When the coolant is 176 degrees the resistance measures 47 to 57 ohms.
When the coolant is 248 degrees the resistance measures 14 to 18 ohms. At ~248 degrees the coolant light should be on.

How to check for proper operation:
1. Remove the left side cover
2. Remove the bolt for the coolant overflow tank and moved it aside.
3. Remove the Temperature Indicator Unit from the holding band so that you can get to the connectors.
4. Disconnect the 2P connector from the Temperature Indicator Unit. It has only wire.
5. Connect a 18 ohm resistor from the only pin on the 2P side of the Temperature Indicator Unit to ground .
6. Turn on the ignition key and the Coolant Light should be on.
7. Turn off the ignition key.
8. Exchange the 18 ohm resistor with a 53 ohm resistor.
9. Turn on the ignition key and verify that the Coolant Light is not on.

This verifies that the Temperature Indicator Unit is functioning properly and that the Coolant Light is not burned out.

Later Valkyries and all Interstates use a Thermostatic Switch to turn the Coolant Light on. The switch is either off or on to control the light.
To eliminate the 97-99 the Temperature Indicator Unit and change to the later Thermostatic Switch do the following.
1, Replace the Thermo Sensor in the Thermostat Housing with the later Thermostatic Switch. You will probably have to change the connector on the end of the wire to attached to it.
2. Remove the Left Side Cover , the Coolant Tank, and disconnect the Temperature Indicator Unit.
3. Jumper the Green/Blue wire on the 2p connector to the Lt Green/Black wire in the 4p connector.
4. The old Temperature Indicator Unit can be removed.

[F6Dave]

That's good info, with a lot more detail.  I would add one thing.  Since the temp light flickering malfunction is so intermittent (it was in my case), if you test the unit with resistors it might appear to be working fine when in fact it is not.  This flickering problem is common enough on the early Valks that if I had the symptoms I'd just do the upgrade.  Actual cooling system problems (other than water pump or hose leaks) are so rare on these bikes that it's unlikely the flickering is caused by overheating.

Sandy, I think this will help.

Here is how I check the operation of the Temperature Indicator Unit and the Coolant Light on a 1997 to 1999 Valkyrie Standard or Tourer

How the light works. The 97-99 Valkyrie Standards and Tourers have a Thermo Sensor on the thermostat housing. The Thermo Sensor has a wire that connects it to the 2P connector on the Temperature Indicator Unit behind the left side cover and overflow tank.
The Thermo Sensor offers a variable resistance to the Temperature Indicator Unit depending on the temperature of the coolant. When the coolant is 176 degrees the resistance measures 47 to 57 ohms.
When the coolant is 248 degrees the resistance measures 14 to 18 ohms. At ~248 degrees the coolant light should be on.

How to check for proper operation:
1. Remove the left side cover
2. Remove the bolt for the coolant overflow tank and moved it aside.
3. Remove the Temperature Indicator Unit from the holding band so that you can get to the connectors.
4. Disconnect the 2P connector from the Temperature Indicator Unit. It has only wire.
5. Connect a 18 ohm resistor from the only pin on the 2P side of the Temperature Indicator Unit to ground .
6. Turn on the ignition key and the Coolant Light should be on.
7. Turn off the ignition key.
8. Exchange the 18 ohm resistor with a 53 ohm resistor.
9. Turn on the ignition key and verify that the Coolant Light is not on.

This verifies that the Temperature Indicator Unit is functioning properly and that the Coolant Light is not burned out.

Later Valkyries and all Interstates use a Thermostatic Switch to turn the Coolant Light on. The switch is either off or on to control the light.
To eliminate the 97-99 the Temperature Indicator Unit and change to the later Thermostatic Switch do the following.
1, Replace the Thermo Sensor in the Thermostat Housing with the later Thermostatic Switch. You will probably have to change the connector on the end of the wire to attached to it.
2. Remove the Left Side Cover , the Coolant Tank, and disconnect the Temperature Indicator Unit.
3. Jumper the Green/Blue wire on the 2p connector to the Lt Green/Black wire in the 4p connector.
4. The old Temperature Indicator Unit can be removed.

[spaldingrb]

Truly appreciate this information - Very Helpful! Best to all...

[indybobm]

That's good info, with a lot more detail.  I would add one thing.  Since the temp light flickering malfunction is so intermittent (it was in my case), if you test the unit with resistors it might appear to be working fine when in fact it is not.  This flickering problem is common enough on the early Valks that if I had the symptoms I'd just do the upgrade.  Actual cooling system problems (other than water pump or hose leaks) are so rare on these bikes that it's unlikely the flickering is caused by overheating.

Tracking intermittent problems can be a pain. The reason I came up with my method of checking the light is that I had never seen it come on. The method also checks the functionality of the Temperature Indicator Unit The one thing I did not do is allow the engine to get up to 250 degrees to check the Thermo Sensor, but now I know that the bulb, the wiring, and the Temperature Indicator Unit is good.

[sandy]

Wow: Great schematic and very simple. Thanks

[indybobm]

Schematics are not from me. I just stole bits and pieces from RP's VALKYRIE WIRING DIAGRAMS from Shoptalk.

[Mike C]

Thanks my friends - I did get the replacemnt indicator through Ebay - the 38710-MZ0-003.  Now I have to find the harness.  I know it is on the left side.  Poking around - getting ready for a bike trip to Michigan - leaving Monday.

Thanks Again

Mike