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Why Shifter Lever Assy breaks on Jeeps

172K views 127 replies 74 participants last post by  Oberlanderperformance 
#1 · (Edited)
After several short term "limp modes' followed by famous 'circled" PRND on EVIC decided to check SLA module, also known as electronic shifter module (ESM), inside. Several people here claimed that after replacement of SLA module they got rid of the problem.

I started with some homework and found German (Mercedes) white papers about 722.6 gearbox. Documents stated that inside the module there are 12 Hall sensors to detect lever position. Hall sensors are known as pretty reliable ones cause they are contact-less sensors. Interestingly, I didn't found any claims on SLA module on several Benz sites.
However when I disassembled SLA module, I found that Chrysler put cheep mechanical contact system inside instead of just a bit more expensive but far more reliable Hall sensor system.
My guess is that it might be a main reason of SLA module failures. Most of them are reported at 30K-40K mileage, right after starting the car in cold mornings. Morning condensation along with a sufficient amount of conductive material accumulated between lamelles may cause position misreading.

The good thing is that it's possible to clean them using contact cleaner, which I did. By the way Chrysler says that it's non serviceable unit and wants more than 300 bucks for part only.

This is picture of PCB

These are lamelles before cleaning

After cleaning

Contacts are different - gold plated for gear position and nickel plated for autostick


I think that's one of a good examples, why Chrysler cars have worst reliability figures than Daimler ones.
 
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#128 ·
My ESM would not allow manual "+" or "-" shifting but would function fine in D. Monitored shifter switches with Solus Edge scan tool and found constant "+" command when in D and active Transmission protection mode. Disassembled ESM, cleaned gold contacts and gaps between contacts on circuit board with qtip and contact cleaner, and reassembled. Also cleaned the main contact strips of board with dry qtip. Works flawless now.
 
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