Tfs

[Coslin]

Hey there everyone. So, I picked up an '01 740iL this weekend. Clean car with 80k-ish miles. The trans failsafe light came on after sitting overnight yesterday and as well as this morning. Turn the car off and re-start it and it goes away. After reading everything and doing some research, it looks like starting with a new battery is the optimal first course of action. The gentleman I purchased it from had the valve body replaced before I picked it up.

Cold start only TFS failure. Step 1. Battery. Step 2.. ?

Thanks!

[Nobleprofessor]

Hey there everyone. So, I picked up an '01 740iL this weekend. Clean car with 80k-ish miles. The trans failsafe light came on after sitting overnight yesterday and as well as this morning. Turn the car off and re-start it and it goes away. After reading everything and doing some research, it looks like starting with a new battery is the optimal first course of action. The gentleman I purchased it from had the valve body replaced before I picked it up.

Cold start only TFS failure. Step 1. Battery. Step 2.. ?

Thanks!

This might sound weird. But, check your tire pressure. Since yours isn't coming on while driving it, this probably isn't the issue. But, I had a Trans failsafe issue on my 95. I figured out one tire was pretty low. When I aired it up and drove it, the issue went away.

[Coslin]

Update:

Had it diagnosed by a reputable dealership. Come to find out, they believe the #5 pressure actuator is malfunctioning electronically. They recommend replacing the transmission due to having the #2 and #5 actuators already replaced by another facility prior to me purchasing the vehicle. Also, like anything else electronic, if you replace one, the chances of the all going eventually increases so you might as well replace them all (valve body) at the same time. But not knowing the condition of the fluid prior to the other shop repairing it, drum and band condition is questionable. Valve body might be a band-aid. Thus, why they recommend a used/reman/etc unit.

Anyone run into something similar to this kind of failure in their years of ownership?

[Timm]

Step 1 is diagnostics - cheap and easy to do yourself these days as long as you have a laptop - and then take it from there. More likely to be a connector problem than the valve body.....

[Coslin]

I can't see a connector problem creating a cold start Transfail Safe Condition. Once the car is up to temperature, on a restart the condition clears itself. And that's just at idle. Not driving in 3rd gear to warm it up, etc.

[Timm]

The EGS tests the electrical connections to each of the solenoids when the ignition is first switched ON - that's why a faulty solenoid or a faulty connector between the car and gearbox looms can throw a TFS condition. But, you need diagnostics rather than just guessing!

[Coslin]

The EGS tests the electrical connections to each of the solenoids when the ignition is first switched ON - that's why a faulty solenoid or a faulty connector between the car and gearbox looms can throw a TFS condition. But, you need diagnostics rather than just guessing!

That's why it's still at a specialist being diag'd.

Going off of your theory, what would allow it to clear itself when the engine is warm? This is a vehicle that has not moved at all and it hasn't been shifted into gear at all. Nothing has moved for the harness to create proper continuity if it indeed did not have good signal prior to the first start. In order for me to clear the TFS, I allow it to get up to full temperature, turn the engine off, open and shut the drivers side door to kill retained accessory power (if applicable), and then restart the car. On this restart, no TFS warning, no 3rd gear default operation AND the PRND display now highlights the P in park (or R or D, etc) when shifted into gear where it missing prior.

Please don't think I am arguing with you. That's the last thing I want to do. I'm trying to understand how it's a cold start failure only. It leads me to believe it electrical in the sense of not enough voltage on start-up or the valve body isn't doing it's job on the cold-start.

What baffles me is it behaves perfectly when warm. Shifts smooth, quickly, no banging, etc.

[kouks]

If the trans works perfectly well when warm, then there is no mechanical problem with the trans. Replacing it will do nothing but cost you lots of $$$$.

Your issue is electrical. Checking battery voltage cold is a good start, you may even have a battery charging issue, and when it cold starts you get voltage issues and a warning, when the alternator juices up the battery a bit, all problems go away. Replacing the shift solenoids is not expensive either, they each cost about $30-50. If you can DIY you will save yourself lots of $$$. Even if you replace the internal wiring harness (about $150) it will be much cheaper than a trans.

If the valve body was replaced with a professionally rebuilt one, then I would suspect the internal wiring harness.

1. Battery voltage
2. Wiring harness
3. Solenoids

In that order.

Also, IF you have access to INPA, with the car NOT RUNNING, you can connect to the EGS (trans computer) when the car is cold and activate the solenoids to see if you have a bad or weak solenoid. This is not an uncommon problem in most auto trans setups. Since you have it at a shop, have them do it with you there, if any of the solenoids do not work well, just replace them. And NO, you don't have to replace them all, just the bad ones, unless you want to be thorough and sleep well at night.

[Timm]

Yes, I agree with Kouks, much more likely to be electrical.

As two actuators are reported as 'failed' I would suspect the supply to them rather than the actuators themselves - they are simply coils of wires, nothing special and although they get swapped out there's never anything wrong with them as they have an easy life!

[Coslin]

My thoughts are electrical as well. Come to find out, they original guy only replaced 2 of the solenoids for the same condition and it didn't work. So, the recommendation is to replace the valve body entirely with a reman unit. Everything I have found online gives me a part # of 24 34 7 521 639. That's right off of bmw of south atlanta. But when I call a dealership, I'm being told it's part # 24 34 1 432 716. I've been quoted anywhere between 3300 - 3800 bucks.

Working backwards with that part # gives me nothing. No where on any online catalog does that show that part #. I am big time confused on this one. Obviously, I trust the dealer as they looked it up by VIN. But why on earth can I not find anything related to this part #?

[kouks]

My thoughts are electrical as well. Come to find out, they original guy only replaced 2 of the solenoids for the same condition and it didn't work. So, the recommendation is to replace the valve body entirely with a reman unit. Everything I have found online gives me a part # of 24 34 7 521 639. That's right off of bmw of south atlanta. But when I call a dealership, I'm being told it's part # 24 34 1 432 716. I've been quoted anywhere between 3300 - 3800 bucks.

Working backwards with that part # gives me nothing. No where on any online catalog does that show that part #. I am big time confused on this one. Obviously, I trust the dealer as they looked it up by VIN. But why on earth can I not find anything related to this part #?

Call Eriksonn Industries in Connecticut, they have rebuilt VBs for about $700. They will also tell you which VB part number it is.

http://www.erikssonindustries.com/

[Coslin]

Call Eriksonn Industries in Connecticut, they have rebuilt VBs for about $700. They will also tell you which VB part number it is.

http://www.erikssonindustries.com/

Thanks for the tip! I appreciate it.

[Coslin]

Just an update: Turns out the failure was the valve body. After replacement, transmission has no failsafe notifications on cold start-up any longer.

While they were repairing the valve body, the immobilizer died. So, I had to overnight my other key and they got everything resequenced after replacement of the immobilizer and the car was good to go.

Until last night when it now cranks, but doesn't fire. Le sigh. I'm pretty sure they overlooked the intermittent crank position sensor malfunction and never changed the sensor. Another delay before I get to enjoy the car some more.