Trans Fail Safe in heavy rain

[m5james]

So I'm having my odd TFS happen again, making this the second time this has happened in say the past 1.5yrs. Once again it also happened while going through a nice rainy area, so clearly something is getting wet and giving me issues.

I'm out of town, but I did bring my Peake code reader with me. The only code I'm getting is camshaft position sensor, which is something I've had for the past week or so anyways, part is in the mail but still hasn't arrived for some reason. I doubt if the two problems are related, but I figured I'd ask the collective since I'm at a loss right now. I've already climbed under the car and tried to find mildly wet or soaked sensor connections, removed and replugged all sensors on the transmission, all to no avail.

I called and spoke to Juergen at www.jie.com because he's a ZF transmission rebuilder, told him what I've done so far and his suggestions were wheel possibly speed sensors. I'm not getting a code for that though, and while the Peake can read and display a general wheel speed code, it doesn't discern between individual wheels. Before I called him I turned the ignition on and held the gas pedal down for 25 seconds. I do notice that sometimes while sitting there with the key on, engine not running, that sometimes the P will turn on and off while still holding the gas pedal down. Him and I tried a few different techniques to get the transmission to reset since the 25 second one above wasn't doing it...he suggested the cycling the key 3x and then starting, checking the brake lights to make sure I don't have a failed brake pedal sensor and seeing if it mattered if I started the car with my foot on or off the brake. While I can get the P to illuminate again, it will either extinguish again while sitting there and/or will go back into TFS mode once I start moving.

As I said though, my problem is that I'm out of town visiting family for Thanksgiving, so I don't have access to my laptop with all my BMW software. I've got another week in town, but I won't drive it back to Boise like this, so short of limping it to a local indy, any suggestions?

[Eurosport]

i have had that happen once a long time ago
short story
check your ECU/DME box for condensation, located passenger side of engine bay up top by windshield. use an electronics spray cleaner on the connections, make sure everything is dry, reset your code and you should be good to go

[Wayne's World]

I just had TFS pop on me for the first time this past weekend. I fixed it and was able to reproduce it again and fix it again as well. Whether I disconnected my MAF while the engine was idling or opened the portion of the intake tube AFTER the MAF (going toward the TB), TFS would pop up. Couple back to back starts and it went away.

[m5james]

Well to update this, I'm not sure if I have it solved yet, but here we go.

After all to various attempts by myself and with Juergen, I called a local BMW indy and spoke to them in regards to reading the codes. While I was still getting the TFS code, I headed out to the shop. On the way I stopped at Autozone and figured I'd see what they're cheap code reader would say. I was able to pull out P0743 (Torque Converter Clutch) and P1748 (Transmission Control Module, Self Test )codes. While sitting in the parking lot, I replied on these threads hoping for some followup information:

http://www.xoutpost.com/bmw-sav-foru...lfunction.html
http://www.xoutpost.com/bmw-sav-foru...ode-p1748.html

It rang a bell with me in the 2nd thread in regards to checking the battery, and maybe even checking the drain areas since I've never done that before. I think I mentioned it before, but for the past few months I've noticed that two of my angel eyes (one on each side, large and small) sometimes don't light up completely when the X hasn't been driven for a few days. I decided to have one of the Autozone guys come out and test my battery at both connections, under the hood and under the compressor. The readings under the hood came out around 300CCA and the machine said my battery was bad, yet when going under the compressor it was back to around 700CCA (stock is 730) and it said my battery needed a charge. I'm quite surprised how much drop there is in CCA's going from the front to the rear, so I'm going to check the large red connection on the framerail underneath the car, clean the connections and maybe apply some delectic grease to help prevent any potential corrosion. Anyways, while I was there I removed and replaced the battery connections under the compressor, and while I didn't have a post cleaner, I'm still not sure if this was the fix I needed or not. I was able to drive like normal from the Autozone to about 20 min. to the shop and haven't had any hiccups since.

I went to the shop and spoke with one of the techs there, who also happens to own an 01 X5. We get to BS'ing and he said that he had a similar issue where he was getting odd symptoms, replaced the battery and all has been good since. We decided to pass on reading the codes for the day and see how things go, so on my way home I drove to another Autozone and grabbed a battery (they're the only ones in town who had one that fit) for $160...two times what it cost for the 69DL in my 740iL Either way, took the battery home, cleaned the posts and connections, installed it and called it a night.

This morning was the test, which started off as a letdown. I hit the unlock button to illuminate the angel eyes...still the same situation. Maybe I'm investing too much into how they're acting vs the true condition of my old battery, but I was hoping they'd glow as bright as they do after a fresh drive. Started the car, and it had a stumble at startup (mind you, I still have a CPS for banks 5-8 in the mail) so I was expecting it. I experienced 3x hiccups when giving it gas while leaving from stops signs throughout the neighbor hood before I hit a road that takes me to Pyramid Lake out here in Reno. The speed limit is 75 and reached it without issue. I got about 5 miles out and turned around. One the nice long straight on the way back, I decided to stretch her legs and see how she does. Other than 1 bounce on the rev limiter going from 4th to 5th gear, she climbed to 130 without effort or anything odd sensations.

Back home in the garage, I guess the only thing I can do now is see how she acts for the remainder of the week before I head back to Boise this weekend...and I hope that charging the battery on the drive may solve my angel eye issue. Short of it pouring down rain again or taking it back to the shop and having any codes read that my Peake reader doesn't tell me, I'm not 100% certain the battery was my issue and I may have waisted $160, but what's done is done.

[m5james]

Originally Posted by Eurosport

i have had that happen once a long time ago
short story
check your ECU/DME box for condensation, located passenger side of engine bay up top by windshield. use an electronics spray cleaner on the connections, make sure everything is dry, reset your code and you should be good to go

I'll have to take a peak in there...it could be the cause of my odd angel eyes issues as well since that's where I tapped the power from. I hate electrical gremlins.