HELLO, i'm new here...my name is david


(1999 Accord LX 2.3L I4)

I've replaced the sensor itself and I also replaced the temperature sensor sending unit..(both under the distributor)

Whenever I turn my car on it just goes from cold straight up to hot. I'm so confused why it's still doing that and I'm getting frustrated.. please don't rule out the cluster because that's my last resort..

PLEASE HELP

 

Unplug the sending unit (the one wire sensor). Make sure the wire doesn't touch metal (use something like electrical tape to isolate the wire). Start the car. If the gauge shoots up to H, then the problem is with the wiring or the gauge inside the car.

 

that doesn't really help. wiring is intact, and the gauge is still able to move?

 

What PAhonda suggested was essentially to check if there was a short in the sender unit wire. If there was a short in that wire, such as it touching chassis ground, the gauge would move even though it is not connected to the sender unit when the ignition is turned to ON.

 

This is how the temperature gauge works:

Engine Coolant Temperature Gauge (’98-’99)
The engine coolant temperature gauge has two intersecting coils wound around a permanent magnet rotor. Voltage applied to the coils, through fuse 9 (in driver’s under-dash fuse/relay box), generates a magnetic field. The magnetic field, controlled by the coolant temperature sending unit, causes the rotor to rotate and the gauge needle to move. As the resistance in the sending unit varies, current through the gauge coils changes, moving the gauge needle toward the coil with the strongest magnetic field.

The coolant temperature sending unit’s resistance varies from about 137 ohms at low engine coolant temperature to between 30-46 ohms at high temperature (radiator fan running).

 

I checked the fuses, theyre all good. how do you reset the ecu?

 

From what you described regarding the gauge moving, it wouldn’t be related to the fuse. Only if the gauge didn’t move, would it be a possibility of the fuse being a problem.

Resetting the ECM will not do anything in regards to the gauge for a 99 Accord.

Basically the problem you describe can be due to:

• Temperature gauge sending unit (which you stated you replaced). Although not as likely in this case, replacement and/or aftermarket parts have been known to be faulty.
• The wire that goes from the sending unit to the gauge. If there is a short in this wire, such as being caused by wire insulation melted or nicked and the bare wire touching chassis/body ground, it will cause the gauge to move up. – Which is why PAhonda suggested for you to disconnect the sending unit wire (don’t let the connector end touch chassis/body ground) and then turn ignition to ON.
• The gauge may be faulty.

 

ok guys heres an update:


since i said i replaced both temp sensor and sending unit for temp sensor..



when I UNPLUG the sending unit, the gauge doesn't rise to hot anymore(rather just stays down like the car is off) ...

so do you think the brand new sending unit is at fault? it was a $12.50 ebay one..

 

Do you have a multimeter or ohmmeter, so that you can do a resistance test of the sending unit?

Unplug the Yel/Grn wire from the sending unit. Measure the resistance of the sending unit between the positive terminal of the sending unit (tip of the sending unit) and engine ground. When it is cold should be about 137 ohms. If the engine is at operating temperature, it should be about 30-46 ohms.

If the sending unit's resistance is about 137 ohms when it cold, then the sending unit may be okay. If the resistance was 137 ohms when cold, your gauge needle shouldn't have moved straight to hot when you turn on the car. In that case, the problem would then most likely be a problem with the temperature gauge in the instrument cluster.

The gauge is separately replaceable from the rest of the instrument panel. You can probably pick one up for not too much at a salvage yard. It isn't that difficult to replace the gauge if it turns out to be the problem.

 

thank you!