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New conductor plate did not fix speed sensor fault
Background: 2000 E55 with ~225,000 miles Transmission's 1st service was done while replacing conductor plate ~4000 miles ago at 221,000mi. I was told that pilot bushing was not leaking and fluid looked normal.
Last week I had a limp home mode activated. Took car to the local indie shop that did trans work before. They ran codes and seeing speed sensor fault, agreed to warranty recently replaced conductor plate. When I picked up the car they said there were copper colored shavings in the pan since the last fluid change 4000 mi ago. I Drove car home with "new conductor plate" and car went into soft limp mode (could reset with key on/off) right before I got home ~5 miles. I made two short trips with car and all was well, 2 days later on next start, got hard shift from P - R and R - D and trans wouldn't shift from 2nd gear.
Top printout is before conductor plate replacement. Bottom printout is 2 days after replacement of conductor plate showing new codes
Took the car back to the shop for them to run codes and same codes as before conductor plate came up with 2 new codes 012 Rpm sensor n2 014 Engine Speed compar. n2 to n3 implausible
They said it's probably a wire or something melted inside the transmission due to its failing. They cleared the codes, and I was able to drive it fine for another 5 miles until limp mode again.
I am presuming that because the pilot busing was dry that there is no atf in the tcu, but did not verify its condition.
The shop says my only option is reman/rebuilt/used trans. I am afraid that this problem could come up again even with new trans.
Any idea what could be causing this? any suggestions for a next step?
At this mileage you could be pending major tranny work - 1st thing is back to basics to assure clean Comm - replace $14 "bushing" with genuine MB/Mopar part - pull TCU and give thorough "flood cleaning" both sides with MAF cleaner - clean connector - air dry before reinstall - clear codes. Total investment $14 + $9 bushing and MAF cleaner and a bit of time.
At this mileage that may not save you - but at least before you need to make decisions you will have solid info..
If I'm reading my ATSG manual correctly...but I do not rebuild automatic transmissions for a living so take this for what it's worth.
Any DTC greater than 96 indicates the error occurred previously. 12 was the code at the time it was pulled; then 96+12=108 which means this is a repeat code. Ditto for the code 14 and 110.
A "soft" fault; one that can be cleared by key off/on, is an indicator of a hydraulic/mechanical issue in the transmission and you are limited to 3rd gear and reverse only. This should show as code 51 or 147 (transmission slipping or "engaged gear implausible". Code 14/110?).
A "hard" fault that must be cleared using the diagnostic system, is an indication of electrical malfunction. In this case, the last selected gear is engaged until the engine is turned off for at least 10 seconds, then 2nd gear and reverse only. There are at least 23 possibilities for this.
A STAR system can confirm the health of the transmission (fill pressure and fill cycles/times for the clutch packs). If the fill cycles are at 15 or greater (=>300ms), the clutch packs are worn out and you have the potential for metal on metal in the clutch plates. With the mileage on yours and only one service known to have been performed, I'd say your transmission had a pretty good run and it's time to put it out to pasture.
The ATSG manual for the 722.6 is not expensive and is 93 pages of gearhead heaven. Highly recommended to purchase.
Had one soft fault after the code clearing. Looked at the TCU for signs of atf contamination, it was clean, but the right connector was slightly ajar. I pressed down on it and heard a nice "Click" as the connector fully engaged the tcu. One 5 mile drive since with no faults,and trans shifting great. Praying this was the source of the speed sensor faults.
You're doing the "right stuff" - clearing faults and assuring clear Comm is key before moving forward - there used to be a GREAT MB tranny shop in Orange - Transmeister (?) but I think that guy retired - harder to find shops that have actual/decent experience with 722.6
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