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It's too bad they didn't include a wider angle photo or a better description of where it is. I suppose it could be as far forward as the C-pillar. What the heck is an "assembly flap"?
This is about a week after the first post, but maybe it’s still needed.
The TPMS module should be inside on the left side of the GLK (US driver side) by the rear wheel well. I think it’s under the plastic trim piece on the rear of the wheel well.
Data has to be transferred so that wheel positions are correctly recognized. Scanners with TPMS capabilities can do this and start a new module from scratch.
FWIW, when I've installed new TPMS sensors (on my new wheels, so from scratch) the sensors were all self-identified by the car without any need for scanning or programming. Really, just plug-and-play. I believe that's the case if you get the truly compatible TPMS sensors, but might be different for others that aren't specific to a MB vehicle.
Mine were automatically acquired in a few miles of driving, in just a few minutes. I don't know if the acquisition is based on miles driven or on time the ignition is on, or even "calendar time".
New sensors will be re-acquired by the system within a few miles. Sometimes it takes longer. However, that’s not necessarily the case for a new (out of the box) module.
A new module needs to have the vehicle data downloaded from the old module to ID which wheel the signal is coming from. If that doesn’t happen, it needs to be initialized to the position of the sensors on the wheels.
Older MB TPMS systems (‘90s-‘00s) did not need module training because antennas at each wheel were hard wired into the module. I thnk the Sprinter vans are still like this. The newer systems are generic, more reliable, and far less expensive.
Last edited by Odd Piggy; Feb 12, 2025 at 11:32 PM.
Reason: Correction
FWIW, when I've installed new TPMS sensors (on my new wheels, so from scratch) the sensors were all self-identified by the car without any need for scanning or programming. Really, just plug-and-play. I believe that's the case if you get the truly compatible TPMS sensors, but might be different for others that aren't specific to a MB vehicle.
Curious about these preprogrammed wheel sensors.
Did you double check that the module got all the wheel positions correct?
No, though I assumed that it had assigned them all to the correct position (based only on something I'd read about the system being configured to sense which corner each sensor was on). I haven't had an inflation issue since then (other than every trip to the grocery store). ;-)
No, though I assumed that it had assigned them all to the correct position (based only on something I'd read about the system being configured to sense which corner each sensor was on). I haven't had an inflation issue since then (other than every trip to the grocery store). ;-)
After researching, that was a stupid question on my part. The sensor relearns the positions correctly when tires are rotated. Apparently there is a logic of some sort that relies on the sensor to be at a different distance from each wheel to determine the tire/wheel positions. Tech at our dealer says that any 433 mHz MB compatible sensors work. The module should be trained once if it is brand new. He said used modules should work with no training as long as they come out of exactly the same model, but may need to be reset with a scanner. Apparently one module type is used on about 100 cars.
After researching, that was a stupid question on my part. The sensor relearns the positions correctly when tires are rotated. Apparently there is a logic of some sort that relies on the sensor to be at a different distance from each wheel to determine the tire/wheel positions. Tech at our dealer says that any 433 mHz MB compatible sensors work. The module should be trained once if it is brand new. He said used modules should work with no training as long as they come out of exactly the same model, but may need to be reset with a scanner. Apparently one module type is used on about 100 cars.
Yes I heard there is a receiver in each wheel well that calculates the distance and whichever is closer to it means it is mounted where and that data gets sent back to the ECU.
2014 GLK350 base model (active) ; 2001 E320 base (retired); 2001 Wrangler soft-top
Yes I heard there is a receiver in each wheel well that calculates the distance and whichever is closer to it means it is mounted where and that data gets sent back to the ECU.
I doubt MB went to that extreme.
Originally Posted by Odd Piggy
Apparently there is a logic of some sort that relies on the sensor to be at a different distance from each wheel to determine the tire/wheel positions.
I'm in agreement with this configuration. Look at the image just below.
Let's assume the (only) sensor receiver is located in the left rear inside panel (as some have suggested) near the left rear wheel (labeled in diagram).
The distance from the sensor receiver to wheel A is different than the distance to wheel B, as is the distance to wheel C, and the distance to wheel D. The software calculation is simple and quick.
(No need for four separate sensor receivers - way more expensive and over-complicated).
Are sensors new ? Is this how you purchased it as Inoperative? How do you know the sensors are working or even the correct ones ? How do you know they are installed?
I would buy one new sensor for MB and instal it. My new sensors from tire rack took 2 days to operate.
my local single guy tire shop would probably charge me 15-25 to replace one sensor.
be sure to get an auto program sensor that does not need programming
We had a Yukon back around 2007 and, after you rotated the tires, you had to go through this procedure whereby the display would tell you to let 5 psi out of tire x, then blow it back up, then on to the next, wash , rinse, repeat.
I'm in agreement with this configuration. Look at the image just below.
Let's assume the (only) sensor receiver is located in the left rear inside panel (as some have suggested) near the left rear wheel (labeled in diagram).
The distance from the sensor receiver to wheel A is different than the distance to wheel B, as is the distance to wheel C, and the distance to wheel D. The software calculation is simple and quick.
(No need for four separate sensor receivers - way more expensive and over-complicated).
Yes I heard there is a receiver in each wheel well that calculates the distance and whichever is closer to it means it is mounted where and that data gets sent back to the ECU.
I think this is what the older MBs had and the Sprinters currently have. My old E320 had an antenna at each wheel hardwired into a module. Module + antennae are about $1200.
Originally Posted by calder-cay
Let's assume the (only) sensor receiver is located in the left rear inside panel (as some have suggested) near the left rear wheel.
The distance from the sensor receiver to wheel A is different than the distance to wheel B, as is the distance to wheel C, and the distance to wheel D. The software calculation is simple and quick.
(No need for four separate sensor receivers - way more expensive and over-complicated).
I think this is what my dealer tech was trying to describe to me. Module and wheel sensors are the only components. Module is around $200.
I think this is what the older MBs had and the Sprinters currently have. My old E320 had an antenna at each wheel hardwired into a module. Module + antennae are about $1200.
I think this is what my dealer tech was trying to describe to me. Module and wheel sensors are the only components. Module is around $200.
I see so MB did had that layout before, guess the newer layout/design is more efficient and still effective.
Thank you- we had the vehicle on the lift earlier today and the technician looked in this exact spot, but couldn't see anything... At this point, I would Venmo someone $20 if they can definitively locate this thing.
MBNoob4, did u ever find TPMS module, I have 2012 glk 350 and finally found where it’s located. It’s directly under spare tire area mounted to front side of spare tub. U will see a wire in spare tire area and it’s directly under that wire. Hope this helps.
Hi All, this is my first post here (not first time visiting) - I cannot seem to find any information here and my dealer has not been helpful.
Our 2012 GLK350 has a defective TPMS module (the computer, not a wheel sensor). I can't seem to find any type of diagram showing the location of the module to even be able to access it, pull it and get a part number. There is some conflicting information as to whether it is located up under the dash on the passenger side (near cabin filter) or under the backseat. It may possibly be located somewhere else entirely. There also appear to be 2 possible parts, one is a small, black rectangular module with two mounting tabs and the other is a slightly larger white rectangular module with a short antennae protruding from the module. I am wondering if the part was redesigned at some point in the 2010 to 2012 GLK models.
Can anyone confirm the location of the TPMS module on a 2012 GLK350? For what it's worth car has AMG package and 20 inch wheels, if that matters.
Thank you.
I found the TPMS control module for my car (ML350 2014) shown in the diagram as part number 10 under the car chassis, it's right below the rear seat as shown in the diagram. the diagram is not clear and misleading as if it's above the tire or under the seats, but it's actually under the car. not far from the rear left tire. chase the wire to find it.
I found the TPMS control module for my car (ML350 2014) shown in the diagram as part number 10 under the car chassis, it's right below the rear seat as shown in the diagram. the diagram is not clear and misleading as if it's above the tire or under the seats, but it's actually under the car. not far from the rear left tire. chase the wire to find it.
Did you replace yours? I have a replacement coming from FCP Euro. Wondering if I have to take it to the dealer to be reprogrammed.
How does this work? Is it interrogating the sensors and measuring the response time? Is it using signal strength? Otherwise, how does it know when the signal was originated?
How does this work? Is it interrogating the sensors and measuring the response time? Is it using signal strength? Otherwise, how does it know when the signal was originated?
Unless @calder-cay actually knows what components are in the module, I haven’t run across anyone who seems to know. Time of flight, signal strength, and poling would all work. But from my experience with signal recognition equipment, the method that is least sensitive to environment and interference would be a phase sensitive detector (PSD). A PSD operating at maybe 4 MHz would see the displacement of the arrival of the peaks of incoming signals to determine which sensor each signal originated from. The detection is time related but does not require time to be actually measured. That system would have the module located at a non-central location like it is. I suggest 4 MHz because that’s a common frequency for crystal controlled oscillators in PSDs. They’re relatively inexpensive and automatically reestablish synchronization of inputs, similar to how the system appears to work.
Long explanation for something I am speculating on.
I guess my question is, wouldn't they all need transmit and receive capability to do any of those things? I mean, maybe that's the case, but no one has said so, yet.
I guess my question is, wouldn't they all need transmit and receive capability to do any of those things? I mean, maybe that's the case, but no one has said so, yet.
Microwatt FM (AM not as accurate) xmtr in each wheel sensor. Rcvr + PSD in module. 2-way coms not needed. PSD finds and syncs signal automatically. Might need to sync module to ECU once to get correct wheel position ID.
We used these things in remote sensing extensively. I still don’t know if this is actually the technology employed.
A PSD operating at maybe 4 MHz would see the displacement of the arrival of the peaks of incoming signals to determine which sensor each signal originated from.
I'm no expert here, hence the questions... Wouldn't each transmitter have to start transmitting at exactly the same time, or on command, which would require receive capability?
I'm no expert here, hence the questions... Wouldn't each transmitter have to start transmitting at exactly the same time, or on command, which would require receive capability?
My expertise, if I ever had any, is decades old. What I do remember is that the PSD needed no connection to the sensors and had no transmitter. Don’t remember if it had a channel for each sensor but was completely self synchronizing. We deployed as many as 6 at a time. The sensors were battery powered and were on as they were randomly put in place. The module with the PSD was powered up and in about a minute would have the pressures from the sensors separated. This all happened in front of the AD converters and computers because we could measure the module outputs with a voltmeter. I remember seeing block diagrams of the synchronization logic, but that is long gone from my memory. I was a field guy, not an electronics tech.
Last edited by Odd Piggy; Nov 28, 2025 at 10:39 PM.
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