2cpaps

Have an Audi A4 1.8T 2000 avant Tiptronic has 155000 miles.
Have the problem while driving and if Im sitting at a stoplight. The PRND432 lights up (SAFE MODE), Have to reset it, starting the car in N position. but is getting worse, more often

code from my VAG-COM,
fault found
Internal Control Module
P0605-35-10

I found a few threads but nothing too definitive some people talk about the ECM module.
Contacts has been checked and cleaned with elect contact clean spray.

Maybe the multi function switch? ($400-$600)
I don't want to change it unless i'm sure that's the issue.

Any help is appreciated!

Thanks,

4Driver4

Is that a TCU code or ECU code? Is the TCU a swimmer?

5v/cyl

Agree that if that is a TCU code then it has been swimming or corroded connectors. If it is a ECU code then it may just be corrosion on 1 or more of the connectors going to the ECU. Problem with the ECU can put the tranny into limp mode as well. Doesn't sound like multi-function switch.

ECS Tuning-Audi

Transmission fluid level might be low. Inspect for leaks its not uncommon for the lines to leak at that mileage.

Jason

turbo510

But too-low fluid will cause obvious malfunctions, such as not going into reverse (which may require more fluid than first gear, as when our Passat was underfilled by a sham shop; marginal reverse was the result), and abnormal gurgling noises. A multifunction switch fault will give a code listing switch F125. Have you also disconnected and cleaned the two connectors at the trans (multifunction sw. and solenoids)?

2cpaps

I'll check the fluid and electric contacts this weekend
I'll let you know

Another detail forgot to tell, once in awhile it does shift kind of hard while slowing down and randomly feels like it slips sometimes from first to second.
Fluid and filter changed at 115000

Thanks

turbo510

Be sure to check the fluid the proper way; trans warm and with engine running. You've done 40K on that fluid, time for a change anyway. I'd just drain and refill this time, the whole job could be done in an hour. I also prefer Valvoline Maxlife ATF.