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OEM TPMS in vehicle installed system and after market TPMS


w6pea

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I bought a new 2016 Jeep Grand Cherokee. It has Oem TPMS built in. I have an aftermarket TPMS system in my 2005 Fleetwood Jamboree 26Q, Is there a way to get them to communicate with each other, because my TPMS has the capability of 10 receiving units. Thanks for any helpful info.

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Really? How does the OEM sensor send the signal to the ECM if not by radio signal?

While a few do still use radio frequency, it is not nearly strong enough to reach a remote receiver. Most no longer transmit that way but if you really want to know, just Google it as there are several articles available on the subject. :P

 

 

HOW DOES THE TIRE PRESSURE MONITORING SYSTEM WORK?

There are two different types of systems being used today: Direct TPMS and Indirect TPMS.

Direct TPMS uses a sensor mounted in the wheel to measure air pressure in each tire. When air pressure drops 25% below the manufacturer’s recommended level, the sensor transmits that information to your car’s computer system and triggers your dashboard indicator light.

Indirect TPMS works with your car’s Antilock Braking System’s (ABS) wheel speed sensors. If a tire’s pressure is low, it will roll at a different wheel speed than the other tires. This information is detected by your car’s computer system, which triggers the dashboard indicator light.

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While a few do still use radio frequency, it is not nearly strong enough to reach a remote receiver. Most no longer transmit that way but if you really want to know, just Google it as there are several articles available on the subject. :P

 

In your first post, you stated that no OEM uses the radio transmitter system. In this latest post, you state that "most no longer transmit that way".

 

I would bet that over 95% of the vehicles on the road with factory TPMS use a radio transmitting sensor in the wheel to indicate tire pressure. There are literally tens of millions of vehicles on the road with such a system. You can buy those sensors at the dealer, at tire shops, on eBay and hundreds of other places. Those sensors send a radio signal to a centrally located receiver, just like the aftermarket TPMS systems do. I doubt the two can be integrated, but I don't know that.

 

I readily admit that I was not familiar with the indirect system you quoted in your post and that may be the system more vehicles are going to today, but I assure you there are many out there which do not.

 

As far as Googling, I did. Here are a couple of sites which sell the TPMS sensors for a 2016 Jeep Grand Cherokee.

 

http://www.autorimshop.com/jeep-grand-cherokee-2016-tpms-sensor.html

 

http://www.factorychryslerparts.com/products/JEEP/GRAND-CHEROKEE/SENSOR-Tire-Pressure/8665630/56029400AE.html

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I found an article about the indirect TPMS system alluded to above. Here is the link http://www.brakeandfrontend.com/indirect-tire-pressure-monitoring-systems-the-tpms-system-that-knows-the-road/

 

An excerpt from that article

 

"Indirect TPMS is not as sensitive to changes in tire pressure as direct systems that actually monitor the air pressure inside the tire, but they are not as expensive either. An indirect TPMS system is a relatively affordable add-on to a vehicle if it is already equipped with ABS. Even so, the vast majority of vehicles that have TPMS use direct systems rather than indirect.

 

One of the weaknesses of indirect systems is that they may not turn on the warning light if all the tires are underinflated by a similar amount. If the recommended pressure is 32 PSI, but all the tires are say 24 PSI (down 25%), the system won’t know there’s a problem because all will be rotating at the same speed when the vehicle is being driven."

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Thanks I guess maybe I will need to get some sensors for the Aftermarket TPMS. I should say I will have to find them I got 10 sensors when I bought the system.

 

Have you called the manufacturer of your aftermarket system and asked them. I'm only familiar with TST, but I know they would welcome a call and inquiry of the type you're asking. Unless the oem sensors just use a totally difference frequency or coding system, there may be a way to do what you're asking. I'd be curious to know also for future reference. Good luck.

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Like Jim, I highly doubt it. The aftermarket TPM systems transmit the information via a radio signal and no OEM one that I know of does that.

the WiKi article clearly states that direct systems employ a radio transmitter. There is no distinction between OEM and aftermarket systems pertaining to methods of communication. I can assure you that all direct systems employ a radio transmitter as there is no practical way to communicate otherwise.

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"Indirect TPMS is not as sensitive to changes in tire pressure as direct systems that actually monitor the air pressure inside the tire, but they are not as expensive either. An indirect TPMS system is a relatively affordable add-on to a vehicle if it is already equipped with ABS. Even so, the vast majority of vehicles that have TPMS use direct systems rather than indirect.

 

One of the weaknesses of indirect systems is that they may not turn on the warning light if all the tires are underinflated by a similar amount. If the recommended pressure is 32 PSI, but all the tires are say 24 PSI (down 25%), the system won’t know there’s a problem because all will be rotating at the same speed when the vehicle is being driven."

 

It's my understanding that my 2014 Honda CR-V uses an indirect system that relies on the ABS sensors. AFAIC it is a piece of junk. All it can tell me is that "one of your tires may be over or underinflated"! IMO that is a worthless warning. Since I already had TST TPMS sensors on the wheels, I purchased an additional monitor from TST for ~$40 and have it programmed to only display the CR-V's tire pressures. It's great; I have a real time display of the actual pressures.

 

Before someone asks the question, no, there is no problem with having the TPMS sensors programmed on both the display in the CR-V as well as the one in the MH. TPMS systems are "one-way"; there is no signal going from the monitor to the wheel sensor so a sensor can send its signal to any number of monitors.

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It's my understanding that my 2014 Honda CR-V uses an indirect system that relies on the ABS sensors. AFAIC it is a piece of junk. All it can tell me is that "one of your tires may be over or underinflated"! IMO that is a worthless warning.

 

 

After reading a little more on the indirect system, I agree. It's apparent that it is just an inexpensive method that the manufacturers came up with to satisfy the federal requirement for TPMS in their vehicles.

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After reading a little more on the indirect system, I agree. It's apparent that it is just an inexpensive method that the manufacturers came up with to satisfy the federal requirement for TPMS in their vehicles.

So when you get the after market tpms in your RV to read the OEM sensors in the tires, invite us all over to see it work.

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So when you get the after market tpms in your RV to read the OEM sensors in the tires, invite us all over to see it work. :rolleyes:

 

Was it necessary for you to make this snarky remark? I never said nor implied that one could do that. In fact, I clearly stated "I doubt the two can be integrated, but I don't know that".

 

My posts were in response to your two contradictory comments, "The aftermarket TPM systems transmit the information via a radio signal and no OEM one that I know of does that" and "While a few do still use radio frequency, it is not nearly strong enough to reach a remote receiver. Most no longer transmit that way" which are both inaccurate.

 

You know, Kirk, you're a pretty knowledgeable guy and I'm sure that many appreciate your contributions here on the forum. However, when you don't know something, it's not okay just to make stuff up. I guess that's one way to get over 27,000 posts, just comment on everything whether you know what you're talking about or not.

 

I'm done responding to you. I guess I'll just do what others have done and put you on ignore.

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I had a problem with the TPMS system in my Ram Truck. It indicated that I had a flat tire on the right front. I took it in to get it fixed they replaced all of the valve stems that had I guess a sending unit on the inside of the tire. I talked to my dealer and he said the system on my Jeep was the same as on my truck. He said they could flash the truck computer to communicate with the Jeep.

The system on my RV just screw on to the valve stems. so more tha likely they will not communicate I will need to do a lot more research I will keep all of you posted. Thanks for you time and suggestions.

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While a few do still use radio frequency, it is not nearly strong enough to reach a remote receiver. Most no longer transmit that way but if you really want to know, just Google it as there are several articles available on the subject. :P

HOW DOES THE TIRE PRESSURE MONITORING SYSTEM WORK?

There are two different types of systems being used today: Direct TPMS and Indirect TPMS.

Direct TPMS uses a sensor mounted in the wheel to measure air pressure in each tire. When air pressure drops 25% below the manufacturer’s recommended level, the sensor transmits that information to your car’s computer system and triggers your dashboard indicator light.

 

Indirect TPMS works with your car’s Antilock Braking System’s (ABS) wheel speed sensors. If a tire’s pressure is low, it will roll at a different wheel speed than the other tires. This information is detected by your car’s computer system, which triggers the dashboard indicator light.

What Kirk said is the basically what the service writer at my dealer that I deal with said almost word for word!

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Was it necessary for you to make this snarky remark? I never said nor implied that one could do that. In fact, I clearly stated "I doubt the two can be integrated, but I don't know that".

Nothing snarky intended, but you are correct that I should have phrased my response differently. I should not have responded defensively and do apologize for having done so.

 

It seems that there are more devices still using radio signals that I had believed. It would be good if someone could figure out a way to use the OEM sensors to monitor the towed vehicle tires on the road but did take you to mean that you thought you could. I suspect that the signal is too weak to reach far, but may very well be possible, but I doubt is the practicality of doing it. One of our resident engineers might even know some way of going about it. If the signal could be detected and then decoded, then compared to the data used by an existing after market system................ Doing so is way beyond my skill set but perhaps not yours. I have lived long enough to have seen things that I believed to be impossible happen before!

 

w6pea "What Kirk said is the basically what the service writer at my dealer that I deal with said almost word for word!"

 

That is probably because I cut an pasted it from the internet, where I got the information that I based my comments upon.

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While a few do still use radio frequency, it is not nearly strong enough to reach a remote receiver. Most no longer transmit that way

 

Since you cut and pasted this from the internet, could you please provide the source for these three statements? I've read about fifty articles about OEM tpms since we started this conversation and I haven't seen any information which supports this. In fact, my take from reading the info is that most OEM still use the Direct tpms systems. A few of the Japanese vehicles have started using the 2nd generation indirect system. Stanley commented that his CRV does.

 

I already provided a link to sensors for the 2016 Jeep Grand Cherokee, which is the vehicle in question for this thread. It uses the Direct tpms system with radio transmission.

 

I couldn't find anything about how strong the radio signal is. I did find that they use a variety of frequencies. Could you please provide the source from which you cut and pasted this?

 

I'm calling BS on your "cut and paste" claim until you provide a source.

 

I apologize to w6pea for sidetracking what should have been an informative and interesting thread. Hope you find out your answer or get it done.

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That is probably because I cut an pasted it from the internet, where I got the information that I based my comments upon.

Surely by now we all should be highly suspicious of anything we get off the internet let alone throwing it out as fact without verification.

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RBH, you state "Surely by now we all should be highly suspicious of anything we get off the internet let alone throwing it out as fact without verification"

 

GEEEEEEEEE didn't you see that TV commercial where the young lady stated "They cant put anything on the internet that isn't true" LOL

 

 

This has been an interesting thread and although my education and experience is more along the lines of AC Power Distribution then Electronics FWIW (Not much) here are my thoughts on TPMS systems.

 

 

A) Its relatively simple for an ABS wheel speed monitor to send direct hard wired analog data to the engines computer as its no more then a magnet passing by a coil pickup which induces a voltage pulse and the wheels speed is determined by the time between those pulses. If a tires pressure is low its smaller diameter causes it to turn faster, and such can trigger a low pressure sensor ALL VIA WIRES (no radio signal transmission) not extremely accurate but relatively low cost in my opinion. NOTE this could also be done optically or using magnets and pickups but I don't know what auto makers used what methods SO NO WARRANTY

 

B) As we all know its possible to wirelessly transmit signals around the world (not just 20 feet from a tire to a receiver) BUT SUCH IS DEPENDANT UPON THE FREQUENCY, TRANSMISSION METHOD, AND POWER. In an automotive application the energy required to transmit a TPMS signal is likely very low and there could be distance limitations, but twenty feet or so isn't that much of an energy user if you look at all the wireless backup cameras and light systems (wireless tow vehicle lights) and other equipment out there IE I don't envision it all that difficult or expensive or an energy problem to transmit a signal 20 feet BUT THIS IS ONLY SPECULATION IM NOT GOOD AT ELECTRNICS

 

ACCURACY: The hard wired ABS speed sensor accuracy could easily be engineered to be extremely good or only nominal as the pickups and frequency and number and location of the magnets etc etc (subject to optics or magnets) determine accuracy BUT IT PROBABLY COSTS MORE TO MAKE IT MORE ACCURATE

 

PURE SPECULATION I learned years ago TO NEVER SAY NEVER AND NEVER SAY ALWAYS here on these boards. So I will NOT say it can or cant be done, but if you want to mate up a radio transmitter system with a factory hard wired ABS speed sensor based system ID BET THATS A COMPLICATED DEVICE !!!!! and NOT what GM is going to help you do lol

 

 

As far as the accuracy of anything posted here, you might want to consider its worth just what you pay for it NOTHING lol IE don't look a gift horse in the mouth or complain if something isn't correct. A good deal is likely accurate while some may be dead wrong BUT ITS UP TO YOU TO TAKE OR LEAVE IT. I have seen a lot of good people do their best to help WHICH I SURE APPRECIATE and I in turn I try my best whenever I can. HOWEVER since our Lord walked the earth NO ONE is infallible and I'm sure mistakes are made INCLUDING ME FOR SURE. Also it takes a good person to man up and admit a mistake and I've found when you're wrong its best to follow the old advice IF YOU FIND YOURSELF IN A HOLE STOP DIGGING LOL............

 

Best wishes and God Bless all here who try to help, I'm sure mistakes are made, but thanks to all who provide assistance. I've sure received my share in the past

 

John T Too long retired electrical engineer and extremely rusty especially on electronics and RF etc SO NO WARRANTY

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Besides the variety of frequency and power issues among wireless OEM systems, from what I've seen in various automotive technical publications, the coding also varies even among different models and years within a given brand. I suspect the complexity and cost of a universal monitor capable of working with all, or even most, OEM systems would be prohibitive at the retail level. The cost of simply adding 4-6 more sensors to an existing aftermarket system will likely remain the lower cost option for a very long time. And that also solves the issue of dealing with the OEM direct wired systems.

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RBH, you state "Surely by now we all should be highly suspicious of anything we get off the internet let alone throwing it out as fact without verification"

 

GEEEEEEEEE didn't you see that TV commercial where the young lady stated "They cant put anything on the internet that isn't true" LOL

I guess that I'm guilty as charged if you consider the Tires Plus website to be an unreliable source, since that was the source that I quoted.

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In that one cut N paste, it stated that an alarm was made if the tire was 25% low. All tire mfgtrs. consider 20% low as "run-flat", meaning that tire is considered unsafe for re-use.

When towing, I use aftermarket TPMS sensors, as the OEM sensors are on a different frequency and cannot be adapted to an aftermarket frequency. Least-ways that is what TST systems told me.

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The tires on our RAV4 Sport are rated for 50 miles at 50 MPH with zero air in them, but I do have our TST monitor set to alert at 30 PSI, 5 under the 35 PSI nominal target.

 

TST is correct about the differing frequencies, but the digital coding used also varies among brands/models/years.

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