p0741 code, no engage signal to TC

Rglrts

Member
Joined
Aug 15, 2019
Location
St. Louis, MO
TDI
2005 Passat Wagon 2.0 TDI
Hi all,
I've just bought a 2005 Wagon with only 85,000 miles on it. She's a real creampuff, driven by a grandpa and serviced on a regular basis. But naturally, it is showing the p0741 code. I borrowed a VAGCOM and did some preliminary checking, and other probing.
The car will drive a few miles, until the tranny is up to 70C, and the TC will lock up. Temperature will eventually go to 95C (too hot?). After 70C, I start losing lockup in 5th, then 4th, then 3rd. When it's warm enough, no lockup, but the tranny shifts fine. When the TC is locked up, there is no slippage.
Here's what I checked:
1) Fluid and filter was changed at 50,000 miles, and was full and clean.
2) TCM is clean and dry.
3) Wire loom has perfect continuity to transmission solenoids and sensors.
4) All 6 solenoids pass ohmmeter test
5) The TOT (transmission oil temp) was within tolerance
6) The OSS (output speed sensor) was 3x the tolerance recommendation
7) The TSS (turbine speed sensor, also called the input speed sensor) was way out, basically open circuit
8) I tapped onto the EDS4 wires and verified that no signal is being sent to engage the TC clutch
If the OSS or TSS (or both) sensors are faulty, wouldn't the normal shifting operation be messed up? And there were 2 different versions of the TSS sensor used, one was a hall effect sensor, and may have a different tolerance than was in my spec book.
Any ideas?
I'm not a VAGCOM expert, and am back in a TDI since I sold my B4 wagon 15 years ago. So be gentle with me :)
Thanks, Bob
 

oilhammer

Certified Volkswagen Nut & Vendor
Joined
Dec 11, 2001
Location
outside St Louis (where it's safe)
TDI
There are just too many to list....
Every time I get a 5HP19 ZF transmission in here with that DTC, I replace the torque converter with a new one. Fixes it 100% of the time. There is a TSB about this. I have never even bothered to check anything aside from scan tool data, and I don't even bother with that any more.

I have never replaced any speed sensors in one. I have replaced a couple solenoids over the years. Literally, a couple. In like 25 years.

But torque converters? I have done a LOT of those.
 

Rglrts

Member
Joined
Aug 15, 2019
Location
St. Louis, MO
TDI
2005 Passat Wagon 2.0 TDI
I know there is a TSB for the seals, but how would bad seals in the TC cause the computer to not issue the lockup signal?
 

oilhammer

Certified Volkswagen Nut & Vendor
Joined
Dec 11, 2001
Location
outside St Louis (where it's safe)
TDI
There are just too many to list....
Once slip is detected, the TCM stops trying, and flags the DTC. This particular condition does NOT place the transmission in limp mode, which is fixed 4th gear, full line (unregulated) pressure, and of course no lockup by default.
 

Rglrts

Member
Joined
Aug 15, 2019
Location
St. Louis, MO
TDI
2005 Passat Wagon 2.0 TDI
Aha... does that reset with every ignition cycle? Because when I let the car cool down overnight I'll get lockup, but I don't have to clear the code.

Can you tell me the normal operating temperature?

I see you're over on Page... not too far from King Burrito :) That gives me an excuse to come in...

Thanks! - Bob
 

oilhammer

Certified Volkswagen Nut & Vendor
Joined
Dec 11, 2001
Location
outside St Louis (where it's safe)
TDI
There are just too many to list....
Just cycling the key will reset the TCM, yes. And the TC lockup command is not as aggressive when the ATF is cold. Which is normal for any car with this type of transmission.

The normal operational range of the ATF temp varies quite a bit, so it would be difficult to say what is "normal", other than if it were too hot, you'd have a DTC set for that too.
 

dogdots

Vendor
Joined
Sep 4, 2002
Location
Kansas City
TDI
None
So...while you are at it you need to rectify the chain driven balance shaft module and change the timing belt and associated bits if you don't have history of it being done by someone trusted (like Oilhammer ;))

Also check the battery tray drain and sunroof drains, take a good look at the suspension and CV joints, as those are all potential trouble spots on the B5.5.

I have owned many of these B5.5's and all of them ended up with a 3rd pedal and manual rower. My mother in law's B5.5 lasted the longest on the ZF before it lost reverse with no warning at 190k. With a stage 2 tune and a 3rd pedal they are a hoot to drive.
 

Rglrts

Member
Joined
Aug 15, 2019
Location
St. Louis, MO
TDI
2005 Passat Wagon 2.0 TDI
Well, I bought it to convert it to manual, but I was hoping to squeak a year out of it with the automatic without pulling the tranny to do the torque converter. Yes I know about the balance shaft delete, I plan on doing that as well as timing belt and other stuff. Thank you!
 
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