Trans Fail Safe Prompt?

[upallnight]

I would think that TSB is for a trans with the neutral safety switch inside the trans, were abrasive particles from the ATF could get into the switch and cause problems. The switch that's in the picture is mounted on the outside of the trans.

I had to replace a neutral safety switch a couple of years ago on a ZF trans, but it wasn't on a BMW. That neutral safety switch looks very similar to the one on my Audi A6 with the ZF 4HP18 trans. After replacing the switch I opened up the old switch and found that a few of the plastic pieces inside the switch had hairline cracks, enough to prevent or cause intermittent contact for the switch, so the computer wasn't able to decipher which gear the trans was in so it put the trans in limp mode.



The trans computer put the trans in limp mode when there are parameters from sensors that are not being met and to save the trans and get you home it goes to limp mode.

What were the codes that were pulled when it went into limp mode?

[Rockit]

Upallnight... I verified buy the dealer it's on the outside under that square cover. Your picture has a different switch pictured and plug connection.

There are two plug connections on the trans, one for that switch and another for the trans ecm. I unplugged cleaned the connections for the hell of it. The plug connections were free of dirt but you never know if some white corrosion may be on a pin. I sprayed all connections down with ACF-50, I also sprayed the neutral safety switch. ACF-50 is like 100 times better than WD-40...Nothing against WD I still use it on other applications...I sprayed ACF-50 on my Triumph Speed Triple instrument cluster dash reset buttons that stopped working...it fixed them. So I drove the truck for 2 days now and no more warning messages. I'm replacing the switch anyway.

The tech did try and pull codes and nothing....I would have to get it in limp mode in order to pin point the defect. Because its intermittent it resets when you turn the key on and off. It can't pick up a bad circuit board unless it's inop at the time of testing.

I've researched this and found other owners have reported they replaced there neural safety switches to cure this problem. I've also seen complaints in deep snow or water people were getting the same complaints and it would go away...thees plugs must have been getting wet. BMW does a great job engineering but sometimes you have to scratch your head....such sensitive parts hung in the elements under the car 6 inches from the road exposed to all kinds of sh@t and that also has to stand up from heat off the trans. My guess is the part has deteriorated letting moisture in and corrosion.

I'm having it installed Mon will test all week and report if fixed. On my model this only effects 2000 to 2002 4.4's only so this is a small sampling of E53's..glad I found the recall/tsb and was able to diagnose this only happens in Park.

[RRPhil]

As I mention here : http://www.xoutpost.com/844101-post2.html the Range Rovers have an identical switch and connector but it has longer wires between the two so that the connector can be mounted above the bellhousing rather than below the pump housing



Phil

[upallnight]

To verify that it is the switch when you replace it, take apart the old switch and see if there is corrosion in the switch. As I posted earlier, my didn't have corrosion, but hairline cracks, but taking the switch apart did prove to me that the switch was the cause of the Trans Failure issue. When my Audi went into Trans Failure mode I was able to read the code and it did state the switch was the cause of the code.

[Rockit]

It's been about 6 days now and all I did way spray the ACF-50 on the trans connectors and neutral safety switch and no more trans failure prong. I drove it the same exact way when I got the light to come on and it's fixed.

I highly recommend anyone with an X5 unplug the two connectors to the trans and spray them down with Bowie Shield or ACF-50 and you will have trouble free operation especially if you live in the Northeast.

I'm having the neutral safety switch also changed just in case...the shop is backed up so maybe tomorrow.