Can a OBDII reader do...

[dave_the_nerd]

I got one of these to scan codes a while back:

https://www.amazon.com/Wireless-Vehicle-Scanner-Adapter-Diagnostic/dp/B076FRK5BT/

It works fine with EOBD-Facile on my iPhone, and it gives me diagnostic codes, which I want, and has a bunch of features I don't understand, because I'm a total n00b. Real Question: With the right phone app or terminal command, would it be possible to query whether or not the radiator fan is on?

I've got this intermittent never-does-it-at-the-mechanic's noise, see (I think I've asked about it here before) and a long list of things I know it isn't, but I haven't eliminated the radiator fan as a potential culprit yet. My first thought was to wire an LED or something so I know when it's on, but that sounds like work.

TIA

 

[boomerang]

I don't believe that whether the fan is spinning or not is something that is monitored. It is turned on or off by various criteria, but whether the fan responds or not is not a feedback item.

Why not disconnect the fan and see if the noise is eliminated? Yes, you'll have to monitor the engine temp to keep from overheating which may or may not be an issue anyway depending on where you live this time of year. I don't know your history on this issue but if it happens with regularity you may not have to have the fan disconnected for long. Obviously if it starts to overheat you will need to pull over and reconnect it.

 

[dave_the_nerd]

I don't believe that whether the fan is spinning or not is something that is monitored. It is turned on or off by various criteria, but whether the fan responds or not is not a feedback item.

Why not disconnect the fan and see if the noise is eliminated? Yes, you'll have to monitor the engine temp to keep from overheating which may or may not be an issue anyway depending on where you live this time of year. I don't know your history on this issue but if it happens with regularity you may not have to have the fan disconnected for long. Obviously if it starts to overheat you will need to pull over and reconnect it.

It's basically every time I drive the car. I live in Minnesota, so as long as I keep moving, the car stays plenty cold.

I will try unplugging it - that sounds easy too. Thanks!

 

[bradly1101]

Hmm. They make those wireless noise mics for diagnostics (pricey, and not usable while driving), but couldn't you get an FM brodcasting wireless mini-mic? You'd have to attach it securely. This one is less than $13.

https://www.ebay.com/i/281761988423?chn=ps

Sorry, not rated well, but they also make bluetooth mics.

 

[boomerang]

It's basically every time I drive the car. I live in Minnesota, so as long as I keep moving, the car stays plenty cold.

I will try unplugging it - that sounds easy too. Thanks!

If the connector is difficult to get to, there may be a relay in an easily accessible spot you can remove that will accomplish the same thing.

 

[bruceb]

You can also just power the radiator fan with 12VDC by itself. Just unplug the motor and connect direct to it. If it still makes noise, then you know it is going bad. If the noise you are trying to find is gone, time to look elsewhere. Could be anything from heater fan motor, belt tensioner, idler pulley, suspension or brake noise, wheel bearings

 

[Rifter]

You can also just power the radiator fan with 12VDC by itself. Just unplug the motor and connect direct to it. If it still makes noise, then you know it is going bad. If the noise you are trying to find is gone, time to look elsewhere. Could be anything from heater fan motor, belt tensioner, idler pulley, suspension or brake noise, wheel bearings

This is what i would do

 

[dave_the_nerd]

You can also just power the radiator fan with 12VDC by itself. Just unplug the motor and connect direct to it. If it still makes noise, then you know it is going bad. If the noise you are trying to find is gone, time to look elsewhere. Could be anything from heater fan motor, belt tensioner, idler pulley, suspension or brake noise, wheel bearings

It's a psycho-cricket noise.

It only makes the noise when I've stopped the car at an intersection, when the car is still fairly cold. (Although not COLD™ - it happens in the summer - just not-warmed-up-yet cold.)

It's not the heater/vent fans or a/c compressor (I turned those off and the noise keeps going) and it's not the engine or s-belt (had the belt replaced and pulleys inspected, and it doesn't change the noise if I rev the engine.) And it's not the wheels or suspension since it only really happens if the car is stationary (when I take off, the noise fades briefly and stops.)

Powering the fan from the battery while the car is off seems like a good plan. I'll probably try that this weekend (need to get some alligator clip leads or something.)

Thanks!

 

[bruceb]

Easier way is go to a salvage yard or local parts store and buy the connector that goes to the fan motor. You can then easily hook it up to battery or 12VDC power supply. Gator clips will work, but depending on where the connector is, will be hard to get in place.

 

[mindless1]

Odds are the ECM is grounding a relay coil to turn the fan on. If so, pull the relay, take a piece of wire/paperclip/multimeter probes with meter set to current range/whatever, and short 12V in to (fan) out... the power supply pins on the relay, not the coil ground.

It gets more complicated if you have two fans and/or two fan speeds. The vehicle owner's manual might list the fuses and relays for each fan and/or different speeds.

Regardless, also check whether there is any problem with the blades cracking or warpage which could have worn the bearings and be an early failure point.

 

[mindless1]

Fan activation is not a function of OBDII, but if the reader can pull the coolant temperature sensor reading, which it likely can if the app used can do live data, and you can determine what temp the ECM turns the fan on at, then you should know when the fan is running. Multimeter probes across the fuse contacts should also indicate it by the current flow.

 

[bruceb]

It would help if we know Make, Model, Year, Engine of the car in question. We can then lookup the wiring for the fans. But just connecting to the fan motors seperately will tell if they are noisy or not.

 

[mindless1]

Keep in mind that you will not have the same fan RPM powering it with the engine off because then it's getting a little below 12.6V instead of closer to 14V... which may or may not effect it making a squeaking bearing noise if that's what it's doing.

This too becomes more complicated with newer vehicles that use their own alternator charging strategy based on a number of variables, and may not consistently keep the system voltage at 14V.

 

[bruceb]

OBDII does monitor engine temperature and turns on one fan to keep engine temp correct if the AC is turned OFF. If the AC is ON, then it will turn both fans ON and keep them on to cool the engine and make the AC do it's job. Depending on the Scan Tool you can command the Fan to Turn ON

 

[dave_the_nerd]

It would help if we know Make, Model, Year, Engine of the car in question. We can then lookup the wiring for the fans. But just connecting to the fan motors seperately will tell if they are noisy or not.

Sorry - I actually thought I had that in OP, but I must have self-edited too aggressively. It's a 2012 Acura TL, base model w/ 3.5L V6. Has a lot of parts in common with the Accord.

 

[Scarpozzi]

Why not do what old people did with baseball cards.....tape one next to the fan in the direction it spins so it makes the fan even louder. That'd tell you when it's on.

OBDII only reads what the computer stuff says.

Available PIDs can be found here:
https://en.wikipedia.org/wiki/OBD-II_PIDs

In the old days the fans were controlled by a simple relay and a thermostat wire. I remember my old Jeep Cherokee's fan would come on and kick off constantly at idle.....maybe a 1-2 minute cycle. It was annoying and probably not very efficient. Anyhoo...if you can figure out what operating range your fan is supposed to have, you should be able to monitor temperature and decide when the fan should kick on and off. I like the bluetooth OBD2 devices and apps because you can have your hood up in your driveway while the engine's running.