Isolating Tire Pressure Sensor Reporting Dropouts on a ’22 Isata 5 28SSX

[SParkie]

Taking our ’22 Isata 5 28SSX on an epic long trip this summer (So. Cal to Glacier, Yellowstone, Grand Teton and back) helped isolate a remaining TP reporting problem with the D/S inner dualie. All other sensors were reporting in a consistent and timely manner in one PSI increments.
We would drive several hundred miles before the D/S inner dualie stopped reporting. In most cases, the sensor would resume reporting pressure within a few minutes.

Observation: Nine loops of excess slideout cable in the electrical bay (between Tire sensor and the receiving antenna on bulkhead between driver’s seat and dinette):

[SParkie]

Moving this wire bundle down to the floor of the electrical bay did not help much.
However, changing its cross-section by orienting it in the direction of travel and along the door opening helped.
Putting it back in the original location resulted in sensor reporting delays and drop outs.
The nine loops of six conductor cable (approx. 20’) have been unbundled and taped to the floor, MUCH better results. I’ll have to wait to fully test this with a trip over several hundred miles.

[SParkie]

I’d prefer to shorten the cable (w/o butt connectors). So far, Lippert has only offered to sell different length cables and has not provided info on the connector or pins used (two 16 AWG and four 22 AWG conductors in each of two cables). Lippert’s best case still leaves 5 or 6 extra feet of cable. I’m not sure that justifies the time or expense involved.

It took a few minutes and several miles before the D/S inner dualie resumed reporting tire pressure. I found it helped to lower the receiving antenna from the original position to just slightly below the bottom of the dinette slideout. I expect it may be possible to resume using the storage under the seat closest to the driver. FYI: I used a thin piece of plywood to hold the receiving antenna on the D/S of the bulkhead with an adjustable clamp. I also cut a rectangular hole in the plywood to ensure the antenna would have less signal attenuation between the antenna and the rear dualies.

Full disclosure (this has been a long standing challenge as summarized below):
1. RAM warrantied all tire sensors (significant help with front tire reporting, not so much on the inner dualies).
2. Reoriented Tire Pressure Stems on dualies by moving them to be 180 degrees apart and not adjacent as done by RAM.
These “stems” contain the transmitting antenna and the first rule in dealing with suspected interference is to reorient or move the antenna.
A. This improved reporting granularity (i.e., frequent one PSI updates).
B. Much easier to fill inner tire on dualies.
3. The Inner Passenger side dualie frequently stopped reporting first. The outer P/S performed significantly better (i.e., furthest from receiver)
A. Reorganized wiring in the G12 “closet”.
B. Added grounded wire mesh to the closet as well as floor area directly above P/S inner tire. Some improvement.
4. Replaced RF Receiver HUB with latest part number (68535936AB) [original was 56029898AB]. No apparent improvement.
A. This part sits inside the plastic cover on the bulkhead behind the driver’s seat. It is not that expensive.
B. However, you need to have every key fob with you in order for a complete reprogram $$$! IMHO: this step was unproductive.

5. Replaced OEM tires with Michelins (Agilis up front and XDS in the rear). Also replaced all six tire sensors with the latest revision (68475571AD, 68475577AD, & 68475578AD). Border Tire in Paramount, CA did a great job, using tape weights vs. OEM pound on weights and they also put on “Alligator Caps” for all six tires. Those caps make it even easier to fill and adjust pressure. No cap to remove or loose. Just wipe the cap surface and air up or down as necessary.
6. Moving the receiving antenna. Tried MANY positions and orientations. Even tried the rear side of the bulkhead because the D/S inner dualie was now the sensor that dropped out first. Also emptied the dinette seat storage area, suspecting the contents were reducing (attenuating) the signal strength.

Frankly, I’m surprised the D/S inner dualie reports at all given the Gen Set is right in the path between sensor and receiver. Now, with the excess slideout cable repositioned, my hunch is enough signal is able to get through between the top of the Gen Set and the sheet metal fire protection above it. In some respects, this path acts a bit like a rudimentary wave guide? I’ll need another road trip to confirm, but this is the best it has ever worked!

Thanks for letting me share,
SParkie

[Lvnthedream]

Thank you for all you testing and write up. I’ll keep following. I’m to the point, I don’t think there is a fix. I’ve done every change that someone has posted and it didn’t work on my I5, 34DS. Thanks again.

[SParkie]

Lvnthedream,
I hear you! Trying to sort this out takes more patience than I realized.

Until RAM replace all six sensors with the “AC” revision, none of them reported on a consistent basis! Then the fronts were reporting > 98% of the time (now 100% with the “AD” revision for roughly 3,500 miles).
RAM’s warranty did two things. First, the P/S rear outer started reporting very consistently – in my mind, ruling out distance on my rig. Second, their mechanic put the D/S dualie together with the valve stem slightly offset (not directly opposite the other tire’s valve stem) – curiously, the D/S rear outer also became more consistent. I took my rig to a Truck Tire Shop and had the tire stems for both dualies repositioned 180 degrees apart. Again, a noticeable improvement, but dropouts started to occur after 20 to 40 miles. On the plus side, I could observe dropouts started with the inner dualies with the P/S being more frequent. I was complaining to RAM and they told me it was probably interference (e.g., issues on ambulances with all kinds of electronics on board). I took a guess that the Truma water heater offered some shielding for the outer tire. That is what lead me to create some grounded shielding in and under the G12 closet to protect the inner tire. Some improvement. Could go 100 or so miles before experiencing a drop out. Not good enough, wanted to replace the tires with Michelin and update all sensors with the then latest “AD” revision. Definite improvement, more granular response, but still had dropouts after going 200 to 300 miles. It was the D/S rear inner that appeared to trigger the dropouts. Interestingly and very unlike previous dropouts, it would often start reporting again after a few miles. That is when I finally noticed the substantial loops of cable that might be interfering. Much better now, needs another long trip to validate. At least, there has been consistent improvement on my rig with these steps.

Having said that, if your front sensors are not reporting, you might want to update to the latest revision. I’d also suggest having the outer dualies repositioned to place their valve stems 180 degrees away from the inner valve stem. Besides, that and some Alligator Caps will make airing up so much easier. If your inner dualies tend to dropout first, try to reposition the slideout cable as described in an earlier post. Come to think of it, your rig has multiple slideouts, I’m curious how much more extra cable might be hanging in your electrical bay?

All the best,
SParkie

[SParkie]

FYI:
Slideout cables are now shortened and this has definitely improved the tire pressure reporting! Now, the inner dualies are the most responsive I've experienced in the last two years / 20K miles. I am currently in the process of fine tuning the location of the receiving antenna (much closer to the floor). Presumably, I will now be able to use the dinette seats for storage?

In addition to a minor reduction in weight, I'm inclined to think taking that much extra wire out of a DC circuit might be helpful during its operation if voltages are marginal?

HTH,
SParkie

Details for those interested:
Lippert would not provide any "proprietary" details about their cables. No, worries, my local electronics shop recognized the connector as a molex MINI-FIT JR. Connector. They even had a nice kit of receptacle, plug, and contacts. I bought two kits WMF-3903PRT Walden Electronics. (~ $5 ea)
1pc Receptacle 39-01-2060
1pc Plug "Housing" 39-01-2061
6pc Male Contacts 39-00-0041
6pc Female Contacts 39-00-0039

Small challenge:
The contacts are rated for 8 AMPS 18-24 AWG, but two of the wires in each cable are 16 AWG. Makes sense as they power the slideout motors. Turns out molex makes contacts that will provide proper crimping for 16 AWG wire. I ended up ordering a small bag of 39-00-0078 from TTI.com (could have used Arrow.com or one other distributor). These contacts fit the housing, but have slightly larger crimp "wings" to hold the conductor. In my mind, this is critical to get a properly formed crimp that passes the 30 lb pull test required for 16 AWG.

Big challenge:
Getting a crimp that conforms to molex specs.
IMO, the existing connectors were non-confirming and that explained why it was virtually impossible to de-pin the existing harness.
My Wirefy open barrel die was too large to properly crimp these contacts. That said, I ended up ordering a molex Hand Crimp Tool (63811-1000). Getting good crimps took considerable practice! The 22 AWG is quite different from the 16 AWG in more ways than one. I found the crimping wings that hold the insulator were too long on each and shortened them somewhat to obtain conforming crimps. Good thing I had some extra contacts to experiment with as well as to perform the weight test. It is the recommended way to confirm your crimp is satisfactory, but it is a destructive test (contact gets crushed).

If you shorten these cables, practice, practice, and test before attempting. Disclaimer, I was a Radar Tech in the military and have repaired numerous cables, but that was more than a few decades ago . Each wire gauge required a different technique. Spent hours practicing and testing. Once qualified and confident, the actual shortening process took less than an hour to complete.

There is helpful downloadable info on molex.com including their Quality Crimping Handbook (63800-0029).
I also ordered a bag of 39-00-0039 to make sure I had more than enough contacts for both gauges.

[SParkie]

Major improvements to tire sensor reporting on the 22 Isata 5.
Shortening the cables resulted in one trip of more that 1,400 miles with no dropouts (failure to report). Ok, we had a few drop outs in a 4,000 mile trip, but we caused them (e.g. , recycle bag with aluminum cans slide between receiving antenna and the slideout). Purse with metal zipper got in the way. Easily rectified.

The receiving antenna was repositioned much lower to the floor. For one reason or another the RF Hub needed to be repositioned closer the receiving antenna.

Also found that two layers of heavy duty aluminum foil (under the rear dinette seat only) made a slight improvement in reception. I suspect this reflects enough rf energy from the rear tire sensors at the right angle to be helpful?

Determined that my Snap Ring wheel covers needed to be stored in the trunk (nowhere near the path of the D/S wheels and the receiving antenna).

Still working out what can or can't be stored in the front dinette seat because it takes anywhere between 200 and 400 miles to experience a drop out. But for now, consistent enough to be useful

[TrailWayz]

We had our Ram dealer disable the OEM TPMS when we took it in for service. The service bulletin is: TSB NUMBER: 22-001-22