TPM malfunction - RDC failure questions - FIXED!
 

My daughters 2013 E70 X5 35d has had a TPM malfunction message for at least a few weeks. I finally got it to my garage yesterday. After reading about internal corrosion problems and general unreliability with the RDCs, I removed and opened it. The inside was perfect. No signs of moisture or corrosion. I then looked at the wiring coming across the frame to the RDC. I noticed that the harness had come loose from one of the plastic supports on a stud near the RDC. On closer inspection, the wrapping on the harness was chewed up in that area and there were wire strands sticking out of the harness. I removed the wrap and the power wire was only hanging on by a few strands. I spliced the wire at that spot and figured that would solve the problem. I check power and ground at the RDC plug and all was good. The ground and the twisted pair of wires near the RDC look fine. The only other parts in the system are the wheel sensors.

Unfortunately the fault is still there. I had bought a K+DCAN cable, but haven't used it yet. I installed all the software today and scanned it with INPA. The RDC module is not showing up on the list of installed modules. I'm assuming that means that the module is bad. I've ordered a used one off eBay, since my daughter is on a tight budget. I'm hoping that will solve the problem. I know I'll probably have to code it with NCS Expert.

I haven't had the wheel sensors checked, based on the fact that the RDC appears to be dead. I figured if the problem was with one or more of the wheel sensors, the RDC would show a fault for that.

Anything else I should look at while I wait for the controller to come?

Thanks in advance for any advice.

Kelly

INPA does not work as well on the E70 as it does on the E90. As a sanity check, you may want to try ISTA+. I have had INPA not see modules that ISTA+ can see.

https://www.bimmerfest.com/forums/sh....php?t=1023698

Thanks, I'll install ISTA+ and give it a try too. I definitely need a sanity check. If ISTA+ sees the RDC, can it do anything to reset it or somehow get it going again?

ISTA+ is more powerful than INPA. Once the scan is finished, you can click on the module to see shop manual information, run tests and see data.

The Autel MaxiTPMS TS401 can read/interrogate/activate the individual TPMS and display sensor ID, tire pressure, tire temperature, sensor battery condition and relearn information. Lets you know if the sensors are functioning at least. Works with ALL sensors.

I've heard good things about the Autel TPMS tools. I guess if the RDC doesn't fix it, I'll try to find someone that has one to check them. I was trying to avoid having to drive around looking for someone to test them for me during the corona quarantine.

ISTA+ also shows the RDC as unresponsive (shows red in control unit tree), so let's hope replacing it fixes the problem. I'm feeling a little more confident in my diagnosis now.

Okay, so the RDC I got off eBay came today. I installed it, but just like the old one, it doesn't even show up in INPA and is shown in red in ISTA+. I tried doing the reset anyway, but it just gives me an error message, which apparently translates to "SG not connected or does not answer RDCKWP". I've already checked for power and ground at the RDC, but not sure how to check the twisted pair. Anybody have any suggestions besides the obvious "ditch the eBay part, buy a brand new RDC and try again"?

Did you splce the twisted pair/bus wiring? You may want to check for continuity between the plug terminal and an area beyond the area that could be potentially bad. Just pierce the insulation with a pin. If the wire got chewed up, it may have been pulled and broken at some point.

The only wire that I found damaged in the area where the harness was not properly secured near the RDC was the power wire. The ground and the twisted pair looked fine. No other part of that harness looked to have been disturbed anywhere near the RDC. I'm gonna get under there and unwrap the harness a little further from the RDC and look again. I looked on newtis, but couldn't determine where the twisted pair ultimately connects. I was hoping to find the other end and check the whole thing. I like your idea of checking continuity beyond where I've already looked. The wire bundle goes into the truck through the rt rear wheelwell below the fuse box. I'll try to find the twisted pair there and check continuity from there back to the RDC.