Has anyone seen this? My 322 temperature dash light comes on (actually flickers from bright to off) as soon as I start the engine. From the schematic the coolant temperature switch grounds if the temperature is too hot. I unplugged the wire from the coolant switch and the light still flickers (mostly bright). What is the V1 diode for in the schematic. Could it be the problem? Where is the diode located?
322 Temperature light on when engine is cool
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Bob,
The diodes V1 and V2 provide a momentary ground path for the temp lamp and the low fuel lamp when the engine is cranking -- this is a test of the lamps to give confidence to the operator that the indicators work and can indeed indicate the trouble condition of over temperature and a low fuel level, respectively should they occur. Because the voltage drops a bit when the starter is cranking (and current draw peaks on the compression stroke) the lamps might appear to 'flicker' as you note. They should go out when the key is returned to the RUN position after the engine starts and the START position is no longer engaged.
If you have a problem, it is that the fuel lamp is not also being lit during cranking...
Chuck
The diodes V1 and V2 provide a momentary ground path for the temp lamp and the low fuel lamp when the engine is cranking -- this is a test of the lamps to give confidence to the operator that the indicators work and can indeed indicate the trouble condition of over temperature and a low fuel level, respectively should they occur. Because the voltage drops a bit when the starter is cranking (and current draw peaks on the compression stroke) the lamps might appear to 'flicker' as you note. They should go out when the key is returned to the RUN position after the engine starts and the START position is no longer engaged.
If you have a problem, it is that the fuel lamp is not also being lit during cranking...
Chuck
Chuck,
The lamp does flicker as the others when starting but it doesn't go out after the engine starts. It keeps flickering, sometime staying on bright. I pulled the wire off the temperature switch and things don't change (light is still on), so the light is getting a ground though another path. Do you know where the diodes are located? I am going to check the wiring with a ohm meter and try to find the ground path. It is just the temperature light that acts this way. The others are fine.
Bob
The lamp does flicker as the others when starting but it doesn't go out after the engine starts. It keeps flickering, sometime staying on bright. I pulled the wire off the temperature switch and things don't change (light is still on), so the light is getting a ground though another path. Do you know where the diodes are located? I am going to check the wiring with a ohm meter and try to find the ground path. It is just the temperature light that acts this way. The others are fine.
Bob
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Bob,
Sorry for my confusion on when the lamp was on/flickering...
I am not sure where the diodes are located, but suspect they are near the ignition switch connector. If both diodes were shorted, then when either of the fuel or temp sensors call for their respective lamp to light, the other would as well. From the TM1591:
<font size="-2"]Diodes (V1 and V2) block engine coolant temperature
lamp access to the ground provided by the low fuel
level sensor. This prevents the coolant temperature
lamp from turning on when the low fuel level lamp
turns on. [/COLOR]
Let us know what you find when you trace things out with the ohm meter. I agree that there must be some erroneous path to ground somewhere.
Chuck
Sorry for my confusion on when the lamp was on/flickering...
I am not sure where the diodes are located, but suspect they are near the ignition switch connector. If both diodes were shorted, then when either of the fuel or temp sensors call for their respective lamp to light, the other would as well. From the TM1591:
<font size="-2"]Diodes (V1 and V2) block engine coolant temperature
lamp access to the ground provided by the low fuel
level sensor. This prevents the coolant temperature
lamp from turning on when the low fuel level lamp
turns on. [/COLOR]
Let us know what you find when you trace things out with the ohm meter. I agree that there must be some erroneous path to ground somewhere.
Chuck
Bob,
You might check to make sure you have the right light in the correct hole. I recently thought the temperature light was on on my 332, but it was really the battery light that was in the wrong hole. Cleaning the battery terminals fixed it. If you have the wiring diagram, you can check the colors of the wires leading to the lights.
A flickering light on start up sounds similar to how a battery light can act.
You might check to make sure you have the right light in the correct hole. I recently thought the temperature light was on on my 332, but it was really the battery light that was in the wrong hole. Cleaning the battery terminals fixed it. If you have the wiring diagram, you can check the colors of the wires leading to the lights.
A flickering light on start up sounds similar to how a battery light can act.
An update - I checked the diodes (they are both good). I checked what Todd suggested but my light was in the correct hole. Eventually, I used an ohmmeter and it tells me that the wire from the temperature switch to the light bulb is shorted to ground somewhere in the harness. I am thinking about the best way to fix that. Think I will cut the cloth off the harness and then look for the short. Possibly I can narrow it down some. Then use some spiral wrap to replace the cloth after the repair. Any thoughts or better ideas on how to fix this short somewhere inside the harness?
Bob
Bob
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