P500 P500 temp guage

[bender]

My p500 temp guage reads max hot all the time. Its not overheating. Can anyone tell me what to check first? Any help would be greatly appreciated. Thanks Bender

 

[Neohio]

Try and bleed all the air out of the system.
Or you have some mice eating some of your wiring.

 

[alloutdoors]

When you "say" all the time, does it register full "hot" after it has sat over night, cold and you just start it up, essentially running it for a 30 seconds or so?

 

[70Bones]

Well, there are only two devices that control that reading, one is the ECT (engine coolant temperature) sensor, which sends a variable signal to the PCM (powertrain control module, aka computer). The computer then sends a signal to the combination meter (dash display), and also turns on the radiator fan when the variable signal from the sensor indicates a high enough coolant temperature.

If the fan is starting and stopping, and keeping it from overheating, then the sensor would be ok. My guess, from my armchair..... is that your display is probably malfunctioning. Just a guess though. Do you have a "good" P500 buddy who you could trade displays with? I don't know how to check the display connection for proper input signal. What year is the buggy? Then I'll do a bit more research.

 

[bender]

Try and bleed all the air out of the system.
Or you have some mice eating some of your wiring.

Ok there is no air in the system so i will check for mice. Thank you very much for your suggestions
Bender

 

[Duckhunt]

If the fan is starting and stopping, and keeping it from overheating, then the sensor would be ok.

This is key. If fan is always on it's the sensor. A temp sensor is nothing more than a potentiometer, or variable resistor, that changes resistance as it's temperature does. Most I've seen and my company uses is the hotter the sensor gets, the less resistance. So a shorted sensor circuit is "hottest". If that's true in this case if you unplug it, the gauge should go to "low" temp on display. First check for bad wires though!

 

[DaddyDubbs]

Also, just a thought on a non sensor direction... If you have been running in mud, or through soupy puddles, check the radiator for mud packed in the fins. Last year at Takeover, I had to rinse or spray radiator off several times to try to clear packed mud and get air flow through core to avoid overheating.

 

[Montecresto]

Also, just a thought on a non sensor direction... If you have been running in mud, or through soupy puddles, check the radiator for mud packed in the fins. Last year at Takeover, I had to rinse or spray radiator off several times to try to clear packed mud and get air flow through core to avoid overheating.

But the op says it’s not overheating. My riding buddy is having this same problem, he’s burped it, checked wiring and all good. Waiting for someone to get this figured out lol.

 

[70Bones]

Duckhunt had a good point, if the fan is running all the time, that coincides with the temp gauge reading full scale, and points to the sensor or wiring. I pointed to the display, but really have never heard of one failing. It's more likely the sensor or a mouse...

We need to know if the fan runs all the time when the engine is running.

 

[Chooglin]

Also, just a thought on a non sensor direction... If you have been running in mud, or through soupy puddles, check the radiator for mud packed in the fins. Last year at Takeover, I had to rinse or spray radiator off several times to try to clear packed mud and get air flow through core to avoid overheating.

I'm with you on this, that would be the first thing I would check!

 

[Mudder]

Clogged at Takeover as well. Thanks to @trigger water for getting us going again. 12v Sprayer and water now onboard.

 

[bender]

This is key. If fan is always on it's the sensor. A temp sensor is nothing more than a potentiometer, or variable resistor, that changes resistance as it's temperature does. Most I've seen and my company uses is the hotter the sensor gets, the less resistance. So a shorted sensor circuit is "hottest". If that's true in this case if you unplug it, the gauge should go to "low" temp on display. First check for bad wires though!

Thanks- the wires seem to be ok. The fan runs all the time. Can you tell me where the sensor is?

 

[Duckhunt]

Right in front and a little higher than the spark plug. Unplug that SOB and if the fan stops and gauge goes down - or may possibly throw a code - you know it's the sensor. If it stays the same we'll look at the ECU, or PLC, or whatever Honda calls the "computer".

 

[DG Rider]

Right in front and a little higher than the spark plug. Unplug that SOB and if the fan stops and gauge goes down - or may possibly throw a code - you know it's the sensor. If it stays the same we'll look at the ECU, or PLC, or whatever Honda calls the "computer".

Actually, when you unplug it, it will run all the time (and set a code w/CEL) because the PGM-FI is in limp-in mode.

 

[Duckhunt]

Right on. I'd still say it's the sensor if that happens because it changed something when you unplugged it. If it was the ECU or wiring that means it's not reading the sensor therefore unplugging it would not change anything.

 

[DG Rider]

Right on. I'd still say it's the sensor if that happens because it changed something when you unplugged it. If it was the ECU or wiring that means it's not reading the sensor therefore unplugging it would not change anything.

Right...but suppose the wiring isn't OK? "Appears to be OK" doesn't sound real thorough to me. So why throw a temp sensor at it when it might not fix it? Sometimes they are so cheap it's easy to do...but i'd need more info to do that myself.

 

[DG Rider]

$33 at RMATV for the temp sensor. I'd definitely be double checking those wires...

 

[Duckhunt]

Right...but suppose the wiring isn't OK? "Appears to be OK" doesn't sound real thorough to me. So why throw a temp sensor at it when it might not fix it? Sometimes they are so cheap it's easy to do...but i'd need more info to do that myself.

Absolutely I'm 100% with you. If it was a wiring issue then unplugging the sensor won't change anything. That's what I'm after. I meant "I still say it's the sensor" IF it changes to a code! Not just kills fan and goes to cool. If the wires or ECU is messed up unplugging it will have no change. That's when I said two posts ago if no change then we'll look at ECU (and should have included wires)!

 

[Duckhunt]

And for the record in my experience ECU's 99.9999% of the time they either work fine or they don't at all, not just one feature like the temp sensor input goes out. Wires or sensor...

 

[DG Rider]

I guess I'm confused about what you're saying...

You said...

Unplug that SOB and if the fan stops and gauge goes down - or may possibly throw a code - you know it's the sensor. .

I'm saying that if you unplug one ( healthy machine with no issues or not), it will ALWAYS start the fan and set a code.