Coolant temperature gauge
Check
1. The circuit consists of the sender mounted in the thermostat housing and the gauge assembly mounted in the instrument cluster If the system malfunctions first check the fuse.
2. If the gauge is not working, remove the fuel tank (see Chapter 4) and access the sender according the appropriate model. Note that on XL600V and XRV750 models, you may be 3 able to access the sender from the side (see illustration). Otherwise access it from the top as follows:
- On XL600V and XRV750-L to N (1990 to 1992 ) models move aside the boot containing the wiring connectors as required.
- On XRV750-P models onward (1993-on) remove the an filter housing (see Chapter 4), then disconnect all the wiring connectors in the bracket above the thermostat housing and draw the connectors out of the bracket.
- On XL650V models remove the left-hand trim panel to access the sender (see illustrations).
![](https://motoinstruction.ru/img/honda/19/125466.jpg)
4.2a. Coolant temperature sender (arrowed) - XRV model shown
![](https://motoinstruction.ru/img/honda/19/125467.jpg)
4.2b. Remove the trim panel...
![](https://motoinstruction.ru/img/honda/19/125468.jpg)
4.2c ...to access the thermostat housing and temperature sender (arrowed)
3. Disconnect the wiring connector from the sender and turn the ignition switch ON (see illustration 4.2a or c). The temperature gauge needle should be on the°C on the gauge. Using a jumper wire attached to the wiring connector terminal, earth the sender wire on the engine - the needle should swing immediately over to the «H» on the gauge. If the needle moves as described above, the gauge is proven good, and the sender could be faulty - check it as described below (steps 8 to 12).
Caution: Do not earth the wire for any longer than is necessary to take the reading, or the gauge may be damaged.
4. If the needle movement is still faulty, or if it does not move at all, the fault lies in the wiring or the gauge itself. Remove the fairing (see Chapter 8) and disconnect the instrument cluster wiring connector(s).
5. Check for continuity in the green/blue wire between the temperature sender and the temperature gauge wiring connector. If there is no continuity, locate the break in the wire and repair it or replace it with a new one. Also check for battery voltage at the sender end of the wire with the ignition ON. If voltage is present, the gauge is faulty and must be replaced with a new one (see Chapter 9).
6. If no voltage is present, check for battery voltage between the black (+) and green or green/black (-) (according to model - refer to the Wiring Diagrams at the end of Chapter 9) wire terminals on the instrument cluster wiring connector(s) with the ignition ON. If voltage is present, replace the gauge with a new one (see Chapter 9). If there is no voltage, check the black and green or green/black wires for continuity between the fusebox and earth (ground) respectively, referring to the Wiring Diagrams at the end of Chapter 9.
Replacement
7. See Chapter 9.
Coolant temperature sender
Check
8. If the gauge is not working in normal use bul the above checks have proven it to be good, access the sender as described in Step 2.
9. Drain the cooling system (see Chapter 1).
10. Remove the sender (see Steps 13 and 14 below).
11. Fill a small heatproof container with coolant and place it on a stove. Using an ohmmeter, connect the positive (+) probe of the meter to the terminal on the sender, and the negative (-) probe to the body of the sender. Using some wire or other suppod suspend the sender in the coolant so that just the sensing head and the threads are submerged, with the head a minimum of 40 mm above the bottom of the container. Also place a thermometer capable of reading temperatures up to 130°C in the water so that its bulb is close to the sender (see illustration 3.14).
Note: None of the components should be allowed to directly touch the container.
12. Begin to heat the coolant, stirring it gently. A Warning: This must be done very carefully to avoid the risk of personal injury.
Refer to the Specifications at the beginning of the Chapter and check the temperatures at which resistance readings should be taken for your model. When the temperature reaches the first checkpoint, turn the heat down and maintain the temperature steady for three minutes. The meter reading should be as specified at the beginning of the Chapter. Turn the heat on again. When the temperature reaches the next checkpoint, again turn the heat down and maintain it for three minutes. The meter reading should again be as specified at the beginning of the Chapter. Take a third reading if required according to you model. If the meter readings obtained are different by a margin of 10% or more, then the sender is faulty and must be replaced with a new one.
Replacement
Warning: The engine must be completely cool before carrying out this procedure.
13. The sender is mounted in the thermostat housing. Access the sender as described in Step 2.
14. Disconnect the sender wiring connector. Unscrew the sender and remove it from the thermostat housing.
15. Apply a smear of sealant to the threads of the new sender, making sure none gets on the head. Install the sender and tighten it to the torque setting specified at the beginning of the Chapter. Connect the sender wiring.
16. Install the fuel tank and any other removed parts according to your model and method (see Chapter 4). Refill the cooling system (see Chapter 1).