2001 a4 1.8t tip 100k. car has been running fine, parked it last night. go to start it this morning and engine just turns over without catching. seems as though no fuel or no spark. never had any probs before now. so im sittin my car thinkin wtf? then i noticed that on the instrument panel on the bottom where the gear indicator is, instead of being all black with red PRND21 it was all red with black PRND21. also i am able to take the trans out of park without having to press the brake pedal, which normally i would have to do. is this some kind of limp mode? unhooked the battery just to see if it might reset something, but same prob occurs. ive had a CEL for a little while for the secondary air pump, i dont know if there are any new codes yet, i dont have a vag yet,im tryin to get it running so i can take it to a guy i know at the stealership. he does side work when i need and he can check the codes, but i need to get it to him first. any help much appreciated.

 

Sounds like your tranny combination/range switch is bad. The range switch tells your tcu/ecu what gear the tranny is in. Maybe if it thinks you are in a drive gear it wont let you start. Try shifting into all the different gears and try to start it with your foot on the brake. Autozone or advance should let you borrow a code reader if you leave a deposit.

 

i was thinking something of that nature, because ive shut it off before without putting in park then tried to start it, but in that case it wouldnt even let the starter turn over.

 

okay i just tried it without being in park and it wont let the starter turn over, so i dont think that it has something to do with the shifter/switch/brake pedal.

 

I am wondering if the TCU is the problem... Typically when the gear display changes like that you have a problem with the tranny electronics/wiring. Could it have gotten wet recently?

 

not sure, i washed it yesterday but nothing out of the ordinary. where is the tcu located?

 

Down by your feet on the passenger side.

 

ill have to take a look. anyone know if theres a way to test the tcu?

 

a VAGcom can look at it for codes... thats best way

 

ok borrowed a vag and i tried to scan engine codes but it said "no response from controller" im thinking maybe the ecu is bad. so then i scanned for codes in auto/trans and i got this:

1 Fault Found:
18258 - Powertrain Data Bus: Missing Message from ECU
P1850 - 35-00 - -

should i clear this code or leave it until i find out what it means? everyone is welcome to chime in if you can help. keep in mind guys that this is the first time ive used a vag, so if theres something i should do or something else to scan for, then lmk.