Hot weather Aisin limp home mode

[DonRam240]

See archived thread “Aisin limp home mode symptom in hot weather CONTINUED”. After the transmission module was replaced a couple of years ago, this seemed to happen less often. I also had our dealer’s mechanic confirm that the connector at the back of the driver side wheel well was in good condition, since it is suspect at times for similar symptoms apparently.
But yesterday soon after leaving home on an 87 degree afternoon, I stopped for fuel and when I restarted we were in 4th gear only limp home mode, with EVIC messages about servicing air suspension and 4wd system not available. This went away after about 20 min. shut down allowing cooling, but came back as soon as I was at highway speed. Remained in limp mode, 4th gear, for entire 100+ miles to the race track. We had our 11 ft Bigfoot camper, and were towing a 9000 lb race trailer.
DTC’s are P0970 and P2509.
TransEngineer has been very helpful in the past with suggested diagnoses and knowing what was NOT likely to be the problem. Now I’m concerned again because our 8 year warranty won’t last forever, and I can’t believe no one else has had a similar problem in the past 5 or so years this has gone on. Thoughts from our experienced forum members are hoped for!
Thanks

 

[Tuesdak]

Solve P2509 first. Separate and load test batteries. Check battery cables and all connections including grounds. An ECM goes "NUTS" when the voltage falls off and it can't make a "0" become a "1" because there isn't enough voltage to do so. (From a bad connection etc.) This causes all kinds of ghost codes from a power problem.

 

[DonRam240]

Solve P2509 first. Separate and load test batteries. Check battery cables and all connections including grounds. An ECM goes "NUTS" when the voltage falls off and it can't make a "0" become a "1" because there isn't enough voltage to do so. (From a bad connection etc.) This causes all kinds of ghost codes from a power problem.

We did replace both batteries recently, but we were careful to put a spare battery in place of the first before removing the other. Replaced one at a time the same way. They had got weak enough that it wouldn’t start so cranking voltage would have been low several times before that.
I’ve cleared the codes now.
Further suggestions? How would the above account for the hot weather limp home symptom?
Thanks

 

[Tuesdak]

We did replace both batteries recently

Before you chase your tail: remove a battery ground then check voltage on both then load test both batteries. New parts don't mean good parts, a bad cable or connection may have killed one... Did you clear or check for codes just after battery replacement? Maybe an old code. If it isn't an old code loss of voltage to the ECM as above will trigger all kinds of codes and malfunctions.

Batteries test good --> Clean battery cable grounds by taking them apart and making sure corrosion isn't hidden under the bolts. When you are 100% sure this is inspected then move on to the second code.

The second code, P0970 Press Control Solenoid C Control Circuit Low, indicates the ECM can't control the transmission pressure: don't drive it as it can slip and burn the trans up. Limp mode can only do so much to save it. This is low voltage from the above, short, bad connection. Fun times tracking the wiring harness problem down. This "fun" is why one goes through the trouble of verifying the batteries and connections first. Do note that oil is an insulator so oil leaking out of a connector is a problem.

As a "module replacement" helped the problem in the past I would look for connector pin trouble at the module. IMO this is a problem with a wire or connection to said wire. A short to ground is a possibility. The #1 PIA thing to find esp. if it's intermittent. The Wiggle Test may help track it down.

 

[Ozymandias]

I recommend a full hard reset of the electronic by disconnect both battery's and wait for a couple minutes before reconnecting them.
Countless problems have been resolved by doing so and it is always the first step chasing electronic gremlins.
Also to keep the Software up to date and have the latest revisions running.

In a fully computerized vehicle the mechanical part can't work properly if the controlling Software is faulty. Changing hardware parts doesn't help at all in this case.

 

[DonRam240]

I recommend a full hard reset of the electronic by disconnect both battery's and wait for a couple minutes before reconnecting them.
Countless problems have been resolved by doing so and it is always the first step chasing electronic gremlins.
Also to keep the Software up to date and have the latest revisions running.

In a fully computerized vehicle the mechanical part can't work properly if the controlling Software is faulty. Changing hardware parts doesn't help at all in this case.

Thank you, will do that. Ironic we avoided it by keeping one battery in place while swapping both.
I appreciate all the responses. I still hope to see a reply from someone who has been through this specific symptom complex and found the answer. And if the hard reset doesn’t fix it, I would like to find a shop in the Northwest with a diagnostician who loves solving these mysteries with connector failures, who could if asked just replace every relevant connector at my cost (warranty won’t cover that) to eliminate those possibilities and maybe cure the problem in the process. This has been four years or more now. It is worth money to solve it if the right person is available. We live near Portland OR, and I would travel some to find the right person.

 

[STeichert]

This is a real shot in the dark, but I remember seeing a video about the wiring harness that goes behind the front drivers side wheel is not well protected and the guy had to get towed. I can't remember if it was a transmission issue but it left him stranded. I believe it wore through some wires on a 2104 Aisin. I couldn't find the video, but that may be a place to look for some bad wires.

 

[DonRam240]

This is a real shot in the dark, but I remember seeing a video about the wiring harness that goes behind the front drivers side wheel is not well protected and the guy had to get towed. I can't remember if it was a transmission issue but it left him stranded. I believe it wore through some wires on a 2104 Aisin. I couldn't find the video, but that may be a place to look for some bad wires.

Thank you. That is the connector that I paid the dealer to inspect, and mechanic said no problems with any of the pins or any other problem found.
Of course he could have missed something, we can't discount that possibility.
What I hope to see is someone's hypothesis for how hot weather towing would selectively cause an intermittent connector problem that would put trans into limp home mode with the consistent addition of those oddball error messages like "service air suspension soon" and "4WD system not available" at the same time. Which connector would be suspect for that pattern, other than the one behind the front driver side wheelwell that's already been checked out? What other underlying problem could explain all those symptoms at once? The symptom pattern is well established now. We need the "differential diagnosis" of what thing(s) might explain all those symptoms at the same time. So far we've been doing (intelligent) throwing spaghetti at the wall hoping something will stick, to no avail.
I returned from the races this morning in cool weather, and there was no problem with "limp home" or error messages.
Separately, the second reconditioned "radio" and the EVIC in front of driver both went black for a period of time TWICE during the trip, without any of the other set of symptoms. The cruise control has also been intermittent, and did not function this weekend.
We have yet to do Ozymandias's suggested hard reset; that is for tomorrow.
Don

 

[sag2]

I would go back to the I255 connector under the truck about where your left foot would be on the floor. Disconnect it and carefully (with a magnifying glass) examine it for any green corrosion. Also make sure each male and female pin is clicked into the lock position. Then spray it with DeoxIT and see if it makes any difference. It will take you 10 minutes to do it, as long as you can crawl under the truck there is no need to have a dealer or anyone else do it.

 

[sag2]

I would go back to the I255 connector under the truck about where your left foot would be on the floor. Disconnect it and carefully (with a magnifying glass) examine it for any green corrosion. Also make sure each male and female pin is clicked into the lock position. Then spray it with DeoxIT and see if it makes any difference. It will take you 10 minutes to do it, as long as you can crawl under the truck there is no need to have a dealer or anyone else do it.

 

[DonRam240]

Sag2, thanks. That is a good suggestion. Believe I have some DeoxIT on hand already, and a good fine detail magnifying glass for such a job.
Would it be heat coming off that LF tire in hot day driving, radiating to the wheelwell liner and then the connector, that would account for the association with hot weather? How would heat alter the connection, or I guess, do we know of other examples where heat caused a connector to misbehave and trigger intermittent error messages etc?
The other detail is the association with load; towing seems more likely than carrying the camper alone to trigger the episodes, but towing wouldn’t change the temp of that front tire much (maybe, net, a little load transfer from hitch spring bars, true, but a small effect.)
My spouse would tell you I don’t do anything mechanical in less than 10 minutes

 

[sag2]

It could still be a solenoid, and besides the wiring, that is about the only other type failure I have seen on the Aisin. They just don't break very often.

 

[DonRam240]

We re-inspected that connector and it was in perfect condition including all pins, clean except road dust, not the tiniest sign of oxidation or corrosion. Used CRC QD contact cleaner for good measure and dried before reconnecting (De OXit hasn’t arrived yet, but I don’t think that will be the “solution.”)
Also did hard reset by disconnecting both battery ground cables for 10+ minutes and reconnecting.
After all this, on startup the same error messages and behavior, but now “fixed” even more than historically. Only DTC is P0970. Clearing it doesn’t change anything; it comes right back every time on startup and that includes this morning in fifty degree weather when we usually would not have expected it.
Now I have a specific request. I know we’ve been in a “what is most likely” reasoning mode for the most part. Can one of you make an “all possibilities” list, including if correct the chance of a rare failure in the PCM that would imitate the solenoid failure electronically. I know from past experience that a PCM gets blamed in desperation fairly often, so I get that. But before I go back to the dealer pushing for another solenoid replacement, I would like to have a comprehensive list of even the rare possibilities. This isn’t an ordinary case anymore.
Thanks, all, again for the time and mental effort!
Don

 

[Tuesdak]

After all this, on startup the same error messages and behavior, but now “fixed” even more than historically. Only DTC is P0970. Clearing it doesn’t change anything; it comes right back every time on startup and that includes this morning in fifty degree weather when we usually would not have expected it.

As the condition is present "now" it should be findable by the dealer mechanic. As you disturbed the connector and the problem is worse I would suggest having them replace the connector pins on both sides of the connector you worked on related to Press Control Solenoid C Control Circuit. Perhaps a pin is loose. This is not a fun failure to find and fix as a loose pin is very intermittent. (I went through this for over a year on a brand new vehicle before it was bad enough to catch in the act.)

@sag2 are there any other connectors in the area that could have been wiggled by work on this connector?

 

[DonRam240]

Tuesdak:
We found 2 other connectors in that area, also checked and OK. Based on your advice (which rings true with my old experiences with pins on another truck) I will have them do the pin replacements for the I 255 connector (ID for it from sag2 post above) whether they will cover it as warranty work or I have to pay for it. Time consuming, fussy job, I know from experience. The truck has now become unreliable for the things we bought it for, racing and camping, so must do what we must do to change that.
For our 2018 3500 Cummins, are there other connectors we should include?
Curious, once your loose pin problem was repaired, did you stop having problems from then on?
Thanks for your efforts.

 

[DonRam240]

Finally stumbled on someone with probably same issue on another forum:
https://hdrams.com/forum/index.php?...aisin-transmission-goes-into-limp-mode.12881/

 

[sag2]

That is the only connector between the transmission and the TCM. I would hard wire the T816 and T817 (pins 24 and 25 in the I255 connector) around the I255 connector. That is easy to do, cut the wires a couple inches beyond the I255 and solder in a short jumper wire around the connector. If that is unsuccessful I would next try replacing the pins for those circuits at the TCM (repair kit
68433097AA) a bit expensive at $250 when you only need two terminals out of the kit, but probably one of the least expensive guesses. I believe you said the dealer has already replaced the solenoid pack, so I would tend to rule that out and go back to wiring. You could also hard wire those two circuits from the transmission to the TCM, since you have to cut them anyway to wire around the I255. On second thought, that would be my next attempt. Since you said the code is active, that is the best time to diagnose the circuits.
Are you erasing the code in the TCM, ECM, or both?


NOTE: Although the name for this DTC indicates it is for Pressure Control Solenoid 3, this DTC actually sets for Linear Solenoid 3.

Possible Causes

LINEAR SOLENOID 3 (+) CIRCUIT OPEN (T817, brown/yellow)
LINEAR SOLENOID 3 (+) CIRCUIT SHORTED TO GROUND
LINEAR SOLENOID 3 (-) CIRCUIT OPEN (T816, white/dark blue)
LINEAR SOLENOID 3 (-) CIRCUIT SHORTED TO GROUND
LINEAR SOLENOID 3
TRANSMISSION CONTROL MODULE (TCM)

 

[DonRam240]

And another forum and thread even more on-target. Given the attention we have already given to connector I 255, this man’s experience sounds much more likely to match mine. I will try to communicate with him on the Cummins forum and find out where/what dealer was involved.
Here is the key paragraph and hyperlink:
Here's a summary of the last month:
(1) A team of Aisin and FCA engineers flew in and spent two days inspecting and troubleshooting my truck
(2) They determined that my "big dang" wiring harness needed to be replaced... PN 6827 1152 AC (see photos)
(3) A couple of extra weeks were wasted by FCA sending the wrong harness to the dealer (twice!)...but they reimbursed me a monthly pmt for my trouble.
(4) Have had my truck for almost two weeks and so far so good.
https://www.cumminsforum.com/threads/aisin-hard-shift-engagement.2300602/page-2

 

[Tuesdak]

Curious, once your loose pin problem was repaired, did you stop having problems from then on?

Yes and no. There were two connectors having trouble. However once they repaired both that problem went away. (Some other brand and an airbag light.) Bumps in the road would both trigger the fault lamp and the next bump would clear it.

 

[DonRam240]

I found Dave Smith, Austin TX area, who posted the above about his wiring harness replacement, on LinkedIn and messaged him asking name of dealer and any details he can provide that would help them resurrect information that might help get the same attention and FCA/Aisin consulting advice for our dealer. Fingers crossed.