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Discussion Starter #1
After replacing the driver side front axle on my '04 GLS 4motion I found myself back in limp mode. When I bought the car I scanned 18034 - Powertrain Data Bus: Missing Message from TCU and it would occasionally go into limp mode until restarted, so I was aware there was most likely a TCM issue. After replacing the axle I scanned the 18034 code again but this time it says Active/Static and the code will not clear. I decided to pull up the carpet and check my TCM to see what I'm dealing with. I immediately noticed that my whole carpet (front and back) is soaked. I could squeeze water out of the insulation under the carpet, and the wires + TCM box were sitting in about 1/2 and inch of water and debris from what seemed to be an old rodent nest that I destroyed 馃槄
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Inside of the black box holding the TCM wasn't soaked but there was some moisture along the edges, enough to make me question if this box is still waterproof. I removed my TCM and set up a space heater in the car to dry out the carpet and wiring, and in the mean time ordered a used TCM off eBay to test out. My TCM looks nearly pristine, there are 3 slots on the connection that have VERY minor corrosion. The interior looks fine too, I can't see any obvious water damage inside.
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My "new" TCM should be arriving today, I'm excited to see if that solves my issue after another day or two of letting floor dry. My plan is to thoroughly waterproof the black box if this TCM does the trick, re-wrap the wiring to prevent mice from chewing wires, and potentially add a small drain plug so any water that gets down there can be easily removed. I don't see any chewed wires but I'd rather be safe than sorry because my area is abundant with small rodents. I do have a few questions;

1- If the replacement TCM doesn't fix the issue, where should I go from there? I would assume that the issue would be in the wiring if that ends up being the case

2- How could I check that the relays that connect to the TCM wiring are working properly? They were soaked as well, they're almost completely dried off now

3- There are 3 pin slots with minor corrosion on the piece that plugs directly into the TCM. Replacing that piece seems like it would be a giant pain in the ass, should I attmept to clean the slots or leave them alone? Is there any way I could test if those connections are faulty?

Thank you all in advance, I don't know where I'd be without all of the information on these forums
 

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#3
I would grab some emery paper and gently sand down the corroded tabs. It wouldn鈥檛 hurt to hit the area with something like stabilant 22a ( or similar NOT dielectric grease!) to improve conductivity between the contacts


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Discussion Starter #4
I had a similar issue, I suggest check for wire corrosion at the splices especially green/red. Check the wiring diagram to determine what wires do what. Also the TCM cover may be a path to ground.
#3
I would grab some emery paper and gently sand down the corroded tabs. It wouldn鈥檛 hurt to hit the area with something like stabilant 22a ( or similar NOT dielectric grease!) to improve conductivity between the contacts


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Thank you both for your advice. Thankfully I plugged in the new TCM tonight and got out of limp mode 馃榿 I'm so relieved that the car is shifting again. Now onto the waterproofing tomorrow!
 

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Discussion Starter #5
Here's an update; still no check engine or any other lights for that matter. I sealed the TCU box with silicone around the edges and then sprayed the thing with loads of flex seal. I'm confident that there will be no water able to get in the box. Onto the next project!
 
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