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I thought there were 3 tpms receivers, two at the fronts wheel fenders, and only 1 at the rear rightside behind the spashback? (125khz???)
You.re right there are only three.
 

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I thought there were 3 tpms receivers, two at the fronts wheel fenders, and only 1 at the rear rightside behind the spashback? (125khz???)
You may be right, but the main point I was making that these modules appear to be inductive couplers operating at 125kHz, the purpose of which is to transmit command signals to the TPMS sensors so they then send pressure data via the 433MHz UHF link to the Remote-Keyless-Entry receiver (as per Fig 3 of the article I posted earlier).
 

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Discussion Starter · #23 · (Edited)
Its the achilles heel, worst nightmare for us C owners when this problem happens.

It was heavily rainning today but I got to disconnect the left side tpms fully and gave her a good clean up but the starter didn't turn with it being disconnected. I'll disconnect the other side tomorrow to see if it makes any difference. I'm not sure how to disconnect the one at the rear though? (by disconnecting the plugs is that bypassing the tpms receiver?)

When I put the keys in the ignition barrel, I don't hear the mechanic sound anymore, of the steering wheel unlocking/locking. You can cycle the key all the way though and it will power up but the starter won't turn.

When he AA man did some tests he said there is power to the pcm, found 5volts at the injectors and power to others components. He removed one of the relays and put in live feed and got the starter turn with the keys in the ignition at start mode and said the starter was ok too.

I will try again tomorrow with the tpms disconnected on bothsides, hopefully luck may change?

Eeeek, these electronics are soo complex and I think the facelift ones are probably even more complex.

If get all donor parts from similar car, will get the whole steering unit, along with keys, pcm, tpms receivers, front passenger cylinder lock, don't want to be chiselling and I possibly made it worser now that its locked, because it was free before. I wonder if the evic would accept it and as to whether it would actually work?
 

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As you said go through all the TPMS connections first and check them for tightness /corrosion it wont cost anything as you said the rear one is supposed to be under the right arch never had the arch liner out to confirm this. Good luck hope you find something:(
 

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Discussion Starter · #25 ·
Cheers buddy, I'll keep it posted.
 

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Why only three wheel well transponders?

The following explanation is provided in the Workshop Manual:

"On vehicles equipped with the premium TPM system, the Wireless Control Module (WCM), commonly referred to as
the Sentry Key Remote Entry Module (SKREEM), uses transponders (trigger modules) located in three of the four
wheel wells on the vehicle to provide it with the location of the tire pressure sensors on the vehicle. Like the base
system, the WCM receives RF signals from all four rotating wheel speed sensors. When the WCM needs to know
which sensor is located at a particular location on the vehicle, it directs the transponder at that location to send out
a low frequency signal to excite the nearby sensor. The WCM then receives that excited signal and knows where
that sensor is located. This auto-locating process only happens in the first 10 minutes of any WCM cycle while
traveling at speeds above 20 mph (32 km/h) (Each WCM cycle ends when the vehicle has been shut off for a time
period of approximately 15 minutes or longer). Once the WCM has performed this to the three locations that have
transponders (left front, right front and right rear wheel wells), it uses the process-of-elimination theory to know that
the fourth sensor ID signal is coming from the left rear tire sensor."

The manual contains a great deal of information - including circuit diagrams - on the TPMS. Well worth using as a reference if you have any problems.
 

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I had the exact same issue with mine about 5 weeks ago. After a 8days faffing and many new components (plus a £750 warranty bill!!) they identified the problem.
Turns out it was the front offside TPMS trigger sensor. As I understand it the trigger feeds back along the Limbus loop to give the "all ok" for the ecu to allow the car to start.
Copied is the link to my thread explaining the issue.
Good luck.


http://www.300cforums.com/forums/eu...0-models/99062-car-dead-left-stranded-m4.html
 

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Discussion Starter · #29 ·
Ok folks, got some good news....

The car started this morning and I'm hoping its not premature. Basically by unplugging both front tmps receivers the car would start as normal and the ignition barrel locks/unlocks and the steering is released when you insert the keys. I'm not sure how by unplugging the receiver has the same effect as bypassing it, or perhaps it is bypass when unplugged but it definately works and gets the engine going.

Looks like if you ever get stranded with symptons relating to immobiliser problem, the first port of call would be to unplug both sides, at least to allow to get home, then you can investigate it further.

I drove to Chryslers and then to work and done around 30 miles and the evic only bonged once reading tmps sensor. Anyways both sides have been ordered and the receivers came to 96.40 pounds inc vat (48.20 pounds eachside), which to me is a reasonable cost say against spending thousands at the dealers and towing cost etc

The receivers are sided and the part numbers are:

Passenger side (K04602503AB)
Drivers side (K04602504AB)

Hopefully should get new ones fitted tomorrow and will clear the codes with the predator. I'll see how it goes and post back. Sofar all looking good :)
 

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That's the best f00kin news I've had for years,hope it works....£200 every 2 years is better than the bill from the stealers....well done matey!....maybe there's a fuse or relay that you can leave out to stop the bongs for the missing TPMS receiver..... Bit like the old proton door open buzzzzzzzz trouble was with the proton if you took that fuse out you also had no brake lights.....anyway...well done...let us ( me really...lol) know......lol
 
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Discussion Starter · #31 ·
Thanks eveyone for the great input. I'll check with the predator tomorrow when fitted, hopefully it should be ok :)
 

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Im glad unplugging them worked for you Good result:banana:
 

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Discussion Starter · #34 ·
Thanks Buddy, you was correct right from the start!

If anyone ever gets stranded with symptoms relating to immobiliser problem, definately I would recommend the first port of call would be to unplug both sides, which if the problem is with the receivers, by unplugging it bypasses it and allows you to get home, safely :banana:

Will see how it goes with the new receivers tomorrow and check for any codes with predator :)
 

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I was thinking the same sort of thing,can't we shove a resistor in like the swirl fix??.. I try and keep up with modern electrics as I have to but somethings are like alchemy until I actually do it myself...then it turns to wizardry ...lol
 

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Yeah,bit like life really......lol
 

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Discussion Starter · #40 ·
The connectors on these modules look similar to that on a swirl motor. If so, I can think of a use for one of these duff components.
Alias, I'll stick with the hemi, its not given me enough grieve :)
 
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