TPMS Sensor System

[JDancoe]

Our new 2015 Ecodiesel has the TPMS sensor system with the instrument cluster readout.
I have purchased a 5th road wheel & tire with the intention of doing 5-wheel tire rotations, and also as a second spare for the Alaska trip we will be leaving on in May.
Has anyone else done this? Is there likely to be any conflict with the TPMS system with a 5th TPMS sensor?
Also, if I install a separate TPMS system on my trailer tires is that likely to cause any problems?

As an aside, how accurate are your TPMS readings relative to your tire gauge pressures? I have a very good, accurate tire gauge that I check my tires with, and the instrument Cluster read-out runs consistently 4-5 psi higher than my gauge pressure.

Thanks, Jack Dancoe

 

[Powder Extreme]

Not sure about a 5th TPMS, but considering it's a "self learning" system, I'm sure it will work. By self learning I mean when you rotate tires, you don't have to tell the system you did so, the front and rear pressures will initially read wrong but within a few miles the system learns the positions and then reads correctly. The system for your trailer will be completely different and won't interfere with the truck at all. I've had the TPMS on a few of my Rams and found them to always be within 1 or 2 PSI. Are you sure your gauge is right? Are you reading them at the exact same time? I ask because tire pressure will easily vary 5 psi between cold and warm tires. More if you are loaded.

 

[AnOldBiker]

I'd call the dealership and confirm with them that you can add another tire to your TPMS system before all that work and money.

 

[sag2]

I will have to look at mine with the scan tool and see if there is a position for the 5th sensor. If the truck only is programmed for 4 sensors when you add the 5th it will not recognize it.

 

[Mingoglia]

I'm not sure if the 1500 has different sensors than my 3500, but I found my 3500 to be exactly the same as my manual gauge. Only exception is when it's sitting, but it sorts itself out once you start driving. For instance, my front tires are at 80psi and when it's sitting it may get up to 87, but once I start rolling it sorts itself out. It could be from the sun beating on it at some point. Also found my '14 Durango is also dead on with my gauge.

 

[JDancoe]

OK, so I'm certain may gauge is accurate. I'm a SCUBA diver, and I have a test bench for servicing my equipment, which incorporates (2) high accuracy pressure gauges, one, analog, 1 digital. Checked against those, it is within 1/2 psi.
The comparison I was looking at was done while traveling with our trailer last fall. When we are in a park, the morning we pull out I check all the pressures on both units. I had noticed the discrepancy when I initially turn on the ignition on the truck. I never did a further comparison after driving a while, maybe Mongolia has a point. I'll check it again tomorrow, before and after I make the 100 mile drive to the dealer for it's first service.

Sag2, yeah, I'd appreciate if you would look into that. I'm also going see what the dealer says about it. I have the new tire, wheel, and sensor all mounted and balanced, and will have them incorporate it in the tire rotation when they service it. Putting it on the ground.) I'm not particularly concerned whether or not the truck senses the 5th sensor (as a spare) or not, if it picks it up when the tire is on the ground. I'm mostly concerned if it might "scramble" the signals from the other sensors.

I've received E-mail twice from FCM informing me of minor glitches, telling me I'm due for an oil change, that I had a brake system warning light, (Parking brake pedal was 1 click down) -and- what the tire pressures are.
Shades of George Orwell! BIG BROTHER is watching! So, I hope I'm not going to cause their watchman to have a nervous breakdown.
I'll post what I find out from the dealer. Thanks guys.
Jack Dancoe

 

[JDancoe]

Well, good news & bad.
I checked & set all the tire pressures before getting on the road, @ 40 psi.
Ign. On – reads LF-37, RF—36, RR- 35, LR- 35

2 Miles down the road- Reads LF-39, RF-41, RR-39, LR-38

End of Trip- Gauge- LF-39, RF-42, RR-41, LR-40
Reads- LF-40, RF- 42, RR-41, LR-39
So, I guess the TPMS is pretty accurate after all.

At the dealer they did the tire rotation ($25.00) and the truck will not accept a 5th sensor, it was necessary to erase one of the original I.D. codes and input the new tire sensor. ($60.00) This will have to be done each time I do the tire rotation.
I’m presently shopping for a TPMS Code Tool, so I will be able to do my own reset & tire rotations.
The tool will cost about $350.00, so I figure with 5000 Mi. Rotations, I will recover the cost at about ½ the tire life.
Oh, well, the joys of modern technology.
Thanks, fellas, for all the input.
Jack Dancoe

 

[AnOldBiker]

JDancoe, let me get this straight, since you change one sensor, the TPMS reader in your truck will NEVER read the new sensor when rotating the tire and you will have to input the new sensor EVERYTIME you rotate ? I'm old, and as you know us old guys might be slow, but this doesn't seem right. Under these conditions, why would anyone want a TPMS in their vehicles ? I would have thought, once you re-educate the TPMS, it would stay into the vehicles memory, like the original calibration of the system with the original sensors. This constant re-calibration at every tire rotation doesn't seem right to me.


Apologize for my thoughts:
I forgot this is for adding a 5th sensor and rotating a 5 tire rotation.
I was thinking of a standard rotation and 4 sensors.
It's hell being old and only on your first cup of coffee for the day.

 

[JDancoe]

Jim,
Yeah, I know what you mean about getting old! Another 2 weeks and I'll be closing the door on 75 years. I was a mechanic for 45 of those years, retired in 2003, and I've sure seen a lot of changes. Honestly, most of them for the better.
As for why anyone would want TPMS, I've been doing a lot of research on these systems. As of 2007 they are mandated by Federal Law on all vehicles. Actually they are probably a good idea overall. Do you remember all the bruhaha over the Ford Explorer (& other SUV) rollovers caused by improper inflated tire in the 1990's? That's apparently what caused it.
At present, TPMS is mandated for all road tires, but not for the spare. Apparently some vehicles that have a full-size spare are programmed for a 5th (Spare) sensor, just not our Ram 1500, which has a temporary spare. The first tire rotation I did, with just 4 tires there was no problem. A few miles down the road and everything reset itself.
But, I like having 5 Full-size tires, and doing a 5-tire rotation. In my opinion, the extra tire increases the usable milage significantly enough on all the tires to pay for itself, and, I've had and seen bad experience with a spare that never gets used, then when it's needed it's either flat, or, in my case, shed the tread and beat up the fender molding in about 20 miles after install, before I could get to a service station. (Remember, I live & drive in the "Wild West" that often has long stretches of open road with no services.)
Incidentally, I do make point of checking the air in the "Donut" regularly on my wife's Prius, even though it has never been on the ground, and I'm seriously thinking of replacing it - just because it's 7 years old.

But, in truth, I didn't even think about the TPMS until AFTER I had purchased the 5th rim and new tire, and even then didn't really consider that the system wouldn't accommodate a 5th tire. I had expected that it might not register #5 on the read-out until it was on the road, but I didn't expect it would refuse the signal totally. Oh, well, live & learn.

Regarding that first cup of coffee. Have you noticed, as I have, how much stronger gravity has gotten over the years? That it's much harder to lift our butts out of the chair now?

Well, I hope my pontificating hasn't bored you to sleep. Have a great day, Jack Dancoe

 

[AnOldBiker]

Jack, you have not bored me, and I'm on my third cup now. But the problem I've noticed is people normally don't check the spare for pressure. I do this once per month. Seems when I needed a spare in the early '70's and the spare was almost as flat as the tire it was to replace, I began a set pattern that has yet to let me down. I am also one that believes if they are mandating TPSM for vehicles, it should be for all 5 tires. That in my eyes is making a safety item a real safety item.

But with that said, have a good day and I need to make a second pot, the wife has emptied the first.

 

[JDancoe]

Jim,
I agree. I have lost count of the number of times I’ve stopped on the road to help someone with a flat tire, and found their spare was flat also. I’m a scuba diver, and usually carry what divers call a ‘Pony Bottle.” (A small tank filled with high-pressure compressed air) and usually was able to fill the spare for them.
Sometimes the spare was so deteriorated it wouldn’t hold air!

The biggest problem is that so many vehicles have the spare located in hard to access locations. For instance, my wife’s Prius requires removing the cargo area floor panel, then a storage tray, and THEN you have to totally remove the spare tire to access the valve stem, because the tire is stored face down!
Lots of people just don’t bother, and I bet most service techs don’t either.
Most pick-ups and SUV’s aren’t much better, requiring that you get under the vehicle to reach the spare, and some of those also have the valve stem located on the “up” side, requiring the spare to be lowered to check /fill.

My own experience was with my ’92 W-250 CTD. It had a full-size spare, but had 4 Aluminum Road Wheels, and the spare mounted on a stock steel wheel. I had moved the spare up into the bed, under a camper shell, where it has both accessible and protected from the weather. (I have a auxiliary fuel tank mounted where the spare had been)
It sat in the bed for 10 years, got pressure checked regularly, but never used. When I needed it, I put it on, and about 15 miles later the tread came off and tore off the front fender molding and mud flap! The tire never went flat, and in fact I was able to limp in to Santa Fe, NM to get a repair.
After that, I got another Aluminum Wheel and started doing a 5-tire rotation program.

Maybe we customers should start campaigning the manufacturers to go to 5-tire TPMS. Maybe the NHTSA also.
Jack Dancoe

 

[AnOldBiker]

Just something as a food for thought.

I just bought my wife a little pickup she wanted and when we arrived home, the first thing I did was get some coffee, then give it a good going over. Fluids, pressures, check filters I could and such. Then I dropped the spare tire, wash and dried, sprayed it with a high silicone rubber protection, lubed the cable and checked tire pressure. Then I flipped it where the stem is pointing down and reinstalled. Now when I check tire pressures, yes I have to get on my back, but I can check all tires monthly as I normally do.

Every year I drop the spare, look it over, respray and reinstall. Never had a spare tire issue since doing this. The old truck was almost 14 years old and with the same spare that I had no concern of it's safety. I do this on every truck I have. Also, since we like being independent. We only own trucks and have a trailer, and we haven't owned a car in decades.

Just food for thought.

 

[sag2]

I looked at my truck and it is only configured for 4 sensors. But this is from the owners manual so I'm suspecting the 5th tire would have worked just by driving it. The truck would have seen one sensor no longer reporting (it knows it isn't rotating) and a new sensor in it's place. After driving about 20 miles it would have turned the light out and replaced the sensor ID with the 5th tire.
If you want to try it out, swap the spare back onto the truck and deflate it a few pounds below the others. Then drive it for a few miles (the TPMS reports to the RFH about once per minute, and it needs 1 out of 10 reports to confirm the sensor location and ID) and see if the dash display picks it up.

2015 RAM owners manual

Vehicles With Matching Full Size Spare
• The matching full size spare wheel and tire assembly
has a TPM sensor that can be monitored by the TPMS.
• If you install the full size spare in place of a road tire
that has a pressure below the low-pressure warning
limit, upon the next ignition switch cycle, a chime will
sound and the “Tire Pressure Monitoring Telltale
Light” will turn ON. In addition, the EVIC/DID will
display a “LOW TIRE” message and a graphic showing
the low tire pressure value in a different color. An
#Inflate to XX# message will also be displayed.
• After driving the vehicle for up to 20 minutes above
15 mph (25 km/h) the “Tire Pressure Monitoring
Telltale Light” will turn OFF and the pressure value
will be updated and return to it’s original color, as long
as no tire pressure is below the low-pressure warning
limit in any of the four active road tires.

 

[JJJ]

Well, good news & bad.
I checked & set all the tire pressures before getting on the road, @ 40 psi.
Ign. On – reads LF-37, RF—36, RR- 35, LR- 35

2 Miles down the road- Reads LF-39, RF-41, RR-39, LR-38

End of Trip- Gauge- LF-39, RF-42, RR-41, LR-40
Reads- LF-40, RF- 42, RR-41, LR-39
So, I guess the TPMS is pretty accurate after all.

At the dealer they did the tire rotation ($25.00) and the truck will not accept a 5th sensor, it was necessary to erase one of the original I.D. codes and input the new tire sensor. ($60.00) This will have to be done each time I do the tire rotation.
I’m presently shopping for a TPMS Code Tool, so I will be able to do my own reset & tire rotations.
The tool will cost about $350.00, so I figure with 5000 Mi. Rotations, I will recover the cost at about ½ the tire life.
Oh, well, the joys of modern technology.
Thanks, fellas, for all the input.
Jack Dancoe

I looked at my truck and it is only configured for 4 sensors. But this is from the owners manual so I'm suspecting the 5th tire would have worked just by driving it. The truck would have seen one sensor no longer reporting (it knows it isn't rotating) and a new sensor in it's place. After driving about 20 miles it would have turned the light out and replaced the sensor ID with the 5th tire.
If you want to try it out, swap the spare back onto the truck and deflate it a few pounds below the others. Then drive it for a few miles (the TPMS reports to the RFH about once per minute, and it needs 1 out of 10 reports to confirm the sensor location and ID) and see if the dash display picks it up.

2015 RAM owners manual

Vehicles With Matching Full Size Spare
• The matching full size spare wheel and tire assembly
has a TPM sensor that can be monitored by the TPMS.
• If you install the full size spare in place of a road tire
that has a pressure below the low-pressure warning
limit, upon the next ignition switch cycle, a chime will
sound and the “Tire Pressure Monitoring Telltale
Light” will turn ON. In addition, the EVIC/DID will
display a “LOW TIRE” message and a graphic showing
the low tire pressure value in a different color. An
#Inflate to XX# message will also be displayed.
• After driving the vehicle for up to 20 minutes above
15 mph (25 km/h) the “Tire Pressure Monitoring
Telltale Light” will turn OFF and the pressure value
will be updated and return to it’s original color, as long
as no tire pressure is below the low-pressure warning
limit in any of the four active road tires.

Great information sag2. Too bad the dealers don't read the owners manual.

 

[sag2]

Great information sag2. Too bad the dealers don't read the owners manual.

Might have saved him $60.

 

[K5IP]

Jack,
I am also a SCUBA diver (padi rescue level). I also like having a pony available, but I also keep my main tanks at a few thousand pounds, and with a home made adapter, I can fill tires for my car/trailer/truck when ever I want.
The nice thing about SCUBA air is that it is, free of water. almost like having a nitrogen fill.
Now in Hawaii and making the best of the tanks.
K5IP

 

[JJJ]

Might have saved him $60.

That's what I was thinking.

 

[JDancoe]

K5IP,
Yeah, I have a 1st stage DIN regulator & a K valve adapter, with a 5 foot Aux. reg. hose. It can be used on any tank I have. Definitely agree with you about clean-dry air from SCUBA tanks.
SAG2, thanks for the info. I learned 2 things from your post. First, I had thought the "user's Guide" I received with the truck was the same thing as an "Owner's Manual". Silly ME!

I finally downloaded a "Owner's Manual" from the Ram website, and, low and behold, there was the paragraph you quoted, that I could never find in the "User's Guide", either printed version or the CD.

Along that line, I have found out that the sensor in the new tire is defective. Checked with a TPMS sensor tester, it shows "No Sensor Detected".
So, while I'm waiting for the replacement sensor, I decided to try the tire on the L/R of my truck, just to see what might happen. The pressure was set at 40psi just like the rest of my tires. After I installed it, the D.I.D. read-out showed the pressure in that tire to be 33psi, the other three tires at 36-38psi. (It was a cold day) When I drove the truck, within about 5 miles the other three tires were reading 39-40psi but the L/R was still at 33. I had to drive over 20 miles at highway speed before it sounded the chime, lit the TPMS warning light, and I got a message "Check Tire Pressure". I did make one stop and shut the truck off, for about 5 minutes, then restarted it to see if it might reset and sound a warning at start-up, but it didn't. Makes one wonder how much we can rely on these systems. I don't think I'm going to throw away my old reliable tire gauge any time soon.

I should have the new sensor this week, and if I don't get side-tracked with Honey-Do's i'll get it changed out and let everyone know how things go.

Jack Dancoe

 

[sag2]

If the sensors are good they report to the WCM, RFH, or BCM (depends on the year, model) once per minute while driving. If the vehicle has sat with the key off for at least 30 minutes they should report at key on. They also report any time there is a significant change in pressure as in air loss from puncture. And they are very accurate. I trust them more than any inexpensive gauge.

 

[JDancoe]

SAG2
Thanks very much for your continued interest and input regarding my TPMS issue, your comments have been very helpful.

I agree with you about “Cheap, Inaccurate tire gauges”. But as I mentioned in one of my earlier posts, I’m fortunate to have a test bench with accurate (tested & certified) gauges against which I can check my tire gauges, which I do on a regular basis.

Really, I’m not disparaging to new technology, just still trying to understand and become comfortable with it.
I retired 13 years ago. Prior to that I was a professional mechanic for 45 years. The first 15 years working in independent repair shops and auto dealerships, both as mechanic and shop foreman and service manager. The last 30 years as a heavy truck – heavy equipment mechanic and shop foreman. This was interrupted by brief periods as a technician with Ford Motor Co. Engineering and Pontiac Motor Engineering, and some time as a commercial truck driver, usually in concert with one of my mechanic positions.
At that time, I stayed on top of new technology through technical journals and training classes and seminars, etc.
Since retirement, I’ve kind of fallen behind the curve. This is why I appreciate your input. Obviously, you are still current.

A side comment possibly relating to the earlier paragraph re: gauges;
When we bought the truck, on the drive home I was cycling through the various screens on the D.I.D, and the TPMS screen showed all tire pressures at 49-51psi. When I got home, I was checking various details prior to setting up a maintenance log for the new vehicle, (VIN, tire information, specified lubricants, etc.) and the door sill label specified 39 psi for the tires, which I assume is for general use, not loaded, or trailer towing.
The tire sidewall data specified a maximum inflation pressure of 44 psi.
When I checked the tires with my gauge, they were at the 50-psi range. So, was the dealer technician’s gauge faulty, or was he just careless, or did he have updated info from a TSB?

During our trip last summer, I went out one morning to move the truck to allow access for another vehicle, and the D.I.D. was set on the TPMS screen when I started it. The read-out showed the L/R tire at 30 psi. They were set at 44 psi for trailer towing. After moving the truck, I checked with a gauge, and it was at 30 psi. I filled it from my scuba tank, and took it to a tire shop for repair.
The interesting thing was, I never got a warning chime, nor did the warning icon in the Speedo cluster illuminate. Was this because I did not drive the vehicle any distance before I re-inflated the tire?

Thanks again, Jack Dancoe