Leaf Tire Pressure Monitoring?

All vehicles these days are required to have a tire pressure monitoring system (thank you, Ford Exploder)...

They basically fall in to two camps:

There is the cheap and limited version that simply uses the ABS wheel speed sensors to compare the rotational speed of the four tires. When a tire drops pressure, it's speed will increase and this can be used to detect a low tire. The main problem with this system is that it won't detect if all tires are equally low. It can also be fooled if you put new tires on only one axle.

The much better but more expensive system actually uses tire pressure sensors in each tire to wirelessly send the actual tire pressure to a monitor in the car.

Does anyone know which version the Leaf uses? Based on the fact that I did not see a tire pressure readout anywhere in the data screens for the instrumentation in the car, I'm forced to conclude that they took the cheap route...

Nissan uses sensors mounted on the wheel on their other models so I would presume they use the same on the Leaf.

The owner's manual mentions that using the tire repair kit will damage the tire pressure sensors, so that seems to corroborate Train's point.

Considering all the other bells and whistles they put on the thing it would seem odd to skimp on that detail.
=Smidge=

What car uses the ABS?

It's too bad that they went to all of the trouble and expense to install a system that can give you actual pressures for each tire, and then screwed it all up by not giving us a way to access that info... Not giving a warning until the tire is down to 30 pounds (6 pounds below factory recommenced pressure) is not really acceptable...

Smidge204 said:

The owner's manual mentions that using the tire repair kit will damage the tire pressure sensors, so that seems to corroborate Train's point.

Considering all the other bells and whistles they put on the thing it would seem odd to skimp on that detail.
=Smidge=

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Smidge204 said:

The owner's manual mentions that using the tire repair kit will damage the tire pressure sensors, so that seems to corroborate Train's point.

Considering all the other bells and whistles they put on the thing it would seem odd to skimp on that detail.
=Smidge=

Click to expand...

If fixing a tire will ruin a sensor - and most sensors I know of cost $100+ - not sure why one would even bother to try to fix the tire. I'd likely just call the tow company to come bring me in, or do a real fix to the tire on the spot. After all - the tow company is free for three years, isn't it? Most of the fix a flat stuff doesn't really "fix" the tire, just slows the leak for a while, so it's not a permanent solution, just a temporary one.

And if the used the expensive wheel sensor - you're out even more money.

The spray goo is a last-ditch effort, I would think.

I'd certainly try the glue-on-a-rubber-rope plug kit first, or an expanding mushroom (Plug-N-Go).

The PSI data from the tire sensors is generally available on the CANBus if you know where to look.

Yes, if a repair is going to cost you a sensor, it looks like it would be smart to purchase a real patch kit and try that first.

Service manual to the rescue.

The tire pressure sensor integrated with a valve is installed on a wheel, and transmits a detected air pressure signal by radio wave.

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I think the sensors cost around $20 and are supposed to be replaced every time the tire comes off of the rim

mynameisjim said:

I think the sensors cost around $20 and are supposed to be replaced every time the tire comes off of the rim

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I know of an owner of a Lexus whose wheels have been thru at least a handful (or more) of tire changes (due to frequent nails requiring removal and patching). One sensor was cracked during that repair process at a tire center, but continues to work fine. The car does not report actual pressures for each tire, only when a sudden or large drop in pressure occurs in any one tire, at which point it pops up an alert, without identifying the bad tire.

LEAFer said:

mynameisjim said:

I think the sensors cost around $20 and are supposed to be replaced every time the tire comes off of the rim

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I know of an owner of a Lexus whose wheels have been thru at least a handful (or more) of tire changes (due to frequent nails requiring removal and patching). One sensor was cracked during that repair process at a tire center, but continues to work fine. The car does not report actual pressures for each tire, only when a sudden or large drop in pressure occurs in any one tire, at which point it pops up an alert, without identifying the bad tire.

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The LEAF sensors report PSI for each tire (along with serial number).

The "car" (dash) just turns it into an idiot light.

Not sure that dealers will go to the trouble, but there is a process in the service manual to re-train the car so that when the tires are rotated the dash indication will be correct if a tire pressure sensor indicates a problem.

Same thing would apply when purchasing new tires, but that's a ways down the road....

If I can get my hands on a Consult tool..

The TPMS serial numbers are shown on the device. Just knowing what the serial numbers are would likely make finding them in the CAN Bus stream much easier. I would guess the tire pressure data is nearby.

The Nissan Tire Pressure Sensor (TPS) is a LOT more than $20, more like $90 one dealer said (as I recall).

Maybe one of the 0, 1, 2, 3 data series (with some missing points at times) we see is something like tire pressure?

GroundLoop said:

If I can get my hands on a Consult tool..

The TPMS serial numbers are shown on the device. Just knowing what the serial numbers are would likely make finding them in the CAN Bus stream much easier. I would guess the tire pressure data is nearby.

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I don't know if you wanted your actual serial number or just the format of the numbers off of a unit, but here is a picture of one of mine. Not the best image, but you can zoom in enough to read the format (3E1028).

garygid said:

The Nissan Tire Pressure Sensor (TPS) is a LOT more than $20, more like $90 one dealer said (as I recall).

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Do they have to be Nissan brand, or are these generic?

For instance, I noticed TireRack offers to provide and mount TPS if you buy wheels and tires together as a package.

.

I wonder if one of our 'hackers' can change the reading for low pressure to 36 (have mine inflated to 41 which is supposedly the highest still-safe pressure).