9k is right. The mileage is stored in the instrument cluster. He's also right that these cant be just switched easily. You need someone with the software to pull the calibration files from one cluster to the next or you'll come up with network error codes. The instrument cluster acts as a gateway to the other modules. Everything has to be program match to be able to communicate with each other.

 

Mileage is stored in the cluster 100%. I know, I've swapped clusters in my car. When it was AT, the AT cluster read 117,800.

I got a MT cluster and PCM from a MT car with 88,275 miles. Plugged it into my car (with the AT PCM still in place) to check that all the gauges worked. Mileage read 88, 275.

Did the MT swap, left the AT PCM in place and drove to the dealer to register my keys into the MT PCM. Left the AT cluster in place so they wouldn't record a lower mileage and report it to carfax as a discrepancy. Installed the MT PCM there and programmed the keys into it. Left the dealership with the MT PCM powering the car and the AT cluster still reading 117,800. Changed to to the MT cluster a couple miles away in a parking lot, now read 88,275.

I've driven the car over 10k miles now. Me and a buddy were having a conversation about the mileage being stored in the PCM or cluster, and so I grabbed my old AT cluster from my shelf and went and plugged it into my car. Still reads 117,800.

If you want a different mileage you can simply swap clusters. There are also computer saavy people who can use a hex editor to change the mileage in a cluster.

 

Not in this car, at least not in my experience. As stated above I've swapped clusters numerous times and never gotten a code...except the time I unplugged a cluster with the key on, which gave me a "lost communication" serial bus code that I had to clear with a scanner. There have never been any operational errors or codes from swapping clusters.

 

Well that sucks. Goes against everything I've read. I had a Mazda6 once that wouldn't crank/start because they swapped the instrument cluster without doing the software. Here's a screenshot of the factory manual stating that you have to do software too! Talk about confusing!

 

Just for posterity I thought I'd update this thread. I grabbed a spare cluster I had laying around, that was totally foreign to my rx8 and it's PCM. Came from a completely different car unrelated to any part in my car.

Plugged it in. Car fired right up, ran and drove perfectly. Mileage of the cluster was retained.

You can swap clusters freely in this car with no worries.

 

What year was it? o.O

 

its not saved on the computer, its saved on the cluster.

 

I once had an '87 Mustang GT that had a busted speedometer cable. The part that screws into the transmission was barely holding on. Didn't read speed or miles.

 

dealership used to be able to alter the odo on the cluster. But mazda removed that feature like a year or 2 ago, said to prevent abuse. Understandable. So now their comps can only copy the cluster's odo, not just type in. But this wont stop people from buying a new cluster tho. Lol but really you can change the odo easily if u know what you are doing. Takes a few wires, some software, and some basic electronic knowledge. Dont think the info is encrypted in the cluster ... Yea shouldnt be that hard. But i think the later model pcb has some sort of secuity against that ... Not 100% sure, never look at them b4