Low tire pressure warning bugged?

[rtmozingo]

I edited the tire pressure settings using FORSCAN. You set what the placard pressure should be, and it calculates when the low pressure light should come on (seems to be 75% of setpoint). I set the front tires to 33psi and the rears to 30psi, so I shouldn't get an alarm prior to 26psi. You can see that strangely, only my front left tire is alarming, even tho it should have the same setpoint as the front right, which is not alarming. It appears to be a bug...anyone have this, and if so, were you able to fix it?

 

[smurfslayer]

I am just wondering - with my out loud keystrokes - would this trip over the -first- tire to register low pressure and then it’s locked in, even though others have come in afterwards and may be even lower.

Programatically, the alert might start as low pressure L/F; subsequent and lower alerts come in and are lower but since the MIL (?) is already lit, it just stays the way it is in the display.

i’ve not tested this, nor does it even qualify as a theory. It’s really just the musings of someone needing more coffee. But it does sound plausible.

 

[rtmozingo]

Prior to adjusting the pressure setting, I'd have the light come in when I was on the edge due to temperature. As the tires would heat up, the alarm has (historically) cleared itself. However, you are correct in that sometimes one tire is reluctant to clear until it has inflated more than others. Perhaps that one went sub 26 and just refuses to clear?

Now that you mention it....when I went offroading I aired down to 26 or so and did not have the low pressure alarm on any tire. It didn't come on until my rear tire (which actually had a nail in it) had deflated under 20.

 

[smurfslayer]

The TPMS are a little screwy. You might be able to test by getting the tires up to temp. drop left rear to the threshold / trip the alert. drive about a mile. drop r/r to threshold or lower and drive some. See if the display changes. re-inflate L/R and drive another mile or so.

it may give us an idea how this behaves. I didn’t pay attention when I was mucking about on the beach earlier this year, since I knew I’d trip the alert.

 

[goblues38]

the PSI reading on the dash is not 100% accurate. Check with a real gauge at the tire and adjust as needed.

 

[rtmozingo]

The TPMS are a little screwy. You might be able to test by getting the tires up to temp. drop left rear to the threshold / trip the alert. drive about a mile. drop r/r to threshold or lower and drive some. See if the display changes. re-inflate L/R and drive another mile or so.

it may give us an idea how this behaves. I didn’t pay attention when I was mucking about on the beach earlier this year, since I knew I’d trip the alert.

They've gotten up to about 29 (40 degree drop in temp makes it hard to get higher than that), but I recall sometimes needing to go 3-4 psi above trip setpoint to reset. More and more I think you are right in that it tripped and just hasn't reset yet.

the PSI reading on the dash is not 100% accurate. Check with a real gauge at the tire and adjust as needed.

Sure, but the warning doesn't trigger unless the dash reading is lower than the setpoint. So even if the tire was at 24 psi, if the dash said 27 it shouldn't be on.

 

[jabroni619]

Mine will do that from time to time too and I don't have anything modified via forscan.

 

[rtmozingo]

Thanks for the input yall. Another forum mentioned the tire has to reach 30 psi to clear warning. I noticed that I'm not having to acknowledge the low pressure alarm (it is just in), and I know I've not exceeded 30 psi since it triggered, so I think it just hasn't cleared yet.

 

[Bulldog17]

If the warning light has been on a while you have to reset it. Key, or button on and turn four ways on then off 3x in under ten seconds. You will get a single honk, that's the reset. If not there are further steps. Look in owners manual.
Just had to reset mine because of temp drop.

 

[Hawaiian Time]

If the warning light has been on a while you have to reset it. Key, or button on and turn four ways on then off 3x in under ten seconds. You will get a single honk, that's the reset. If not there are further steps. Look in owners manual.
Just had to reset mine because of temp drop.

Houston we have a problem. Space Shuttle Command Module. Run around the Truck 3 times with the door open, lower the tailgate with the remote, close it yell RESET, then get in truck close door, start engine, rev to 3k rpm, press brake 3 times and flash high beams. Truck will reboot. Did you get that Scotty? Zulu Warp Factor 9...

Ahhhh too much coffee!

By the way FordPass ALWAYS has a Low Tire Pressure Warning in the App Alerts no matter what pressure my tires are at. No Alert on the dash. Im running 38 psi front 34 rear. Its been like that 2 years?!!

Aloha, HT