I’ve been lurking here for MONTHS since googling my DIC codes and getting frustrated that none of the fixes worked for me.

04 A4 Frc.
I think my problem started when I was herding some geese across the street while I was turning onto the road and revved at them. I heard a grinding sound but had no engine codes and it drove fine for a few days. I drove to work one night and on break I came out to go to the store and when I tried to start it up it hardly cranked a few times and started clicking like the battery was dead all of the sudden. Okay nbd, had a power stroke give me a jump but it would hardly crank still but not turn over
I pushed it from the spot it was in our if the way incase it was down for a few days.
The codes I have are
U0107hc
B2587hc
1276hc
B2592hc
C1276hc
I used some sandpaper pads to clean all the grounds in the engine bay, sprayed them with wd40.
got a new battery, cleaned the inside of the battery connections with the sandpaper and sprayed them with wd40 to be sure. Hooked up the battery and got the same result. Reduced engine power. Will crank but won’t turn over. There’s pressure in the fuel line too. It acts like it’s in flood mode.
tool off my throttle body and took it inside and sandblasted it, inspected the connections, no rust, no discoloration or corrosion. Blew it out with an air hose and hooked it back up. No dice. Used a volt meter to check the fuses under the hood and in the passenger compartment and all were good. The guy I had helping me shined a light and saw that the belt for the AC had come loose though. (I did see someone who had a similar problem here but didn’t see what their fix was for it.
The dealership was booked months out so I had it hauled to Midas and they did their diagnostic and put the ac belt back on and said it was likely the TAC module, stole my dash temp sensor grille (okay whatever ) The dealership said they couldn’t find the part and I couldn’t take it there. Again whatever, found them used online. I just want to ask the internet experts here to be absolutely CERTAIN that’s what I need because before I was convinced it was the map sensor and brought it to midas for them to put in for me but they said that wasn’t it.
Now I’m getting frustrated because the HOA neighborhood I live in have complained enough about it sitting in my driveway (fully assembled, see my profile pic) and was told by the code inspector that it can’t sit in MY DRIVEWAY if it doesn’t function and it can be towed and I can be fined $1,000 for it
goofiest manure I’ve ever heard of.
So I ask, the corvette gurus of the internet do you fellows have any suggestions? Getting tired of having it towed somewhere just to pay the diagnostic fee just for them to tell me to have it towed from there because they don’t have the space for it

 

Do you see any movement of the tachometer needle? No movement of the tachometer means the crank sensor has failed, if it has failed you will have no spark and no injector pulses.

 

yeah, we’ve got tach movement

 

Next thing to do is retrieve the DTC codes and post on them here.

 

U0107hc
B2587hc
1276hc
B2592hc

 

For any single module “no comm” you want to check it’s power and grounds…I wouldn’t listen to the idiots at Midas for a diagnosis !!…this is all of us Internet experts can do for you unless you want to flatbed your car down to me in Florida !!..how did it go from being a TAC module to MAP sensor ????

 

I saw the tach sweep with the ignition on but didn't hear you crank the engine. Maybe I missed the start attempt? I'm on mobile fwiw.

 

Ops, I see you have posted the codes.

 

Doesn't look like u0107 is a loss of communication for the C5. The C5 U codes for loss of communication are all U10xx. P0107 is the code for MAP sensor low voltage. The other codes are for column lock and delivered torque signal error. Of the error codes the most likely cause of the no start would be the MAP sensor. The OP needs a scanner to see what the MAP sensor is reading. Also is the car actually cranking but not starting? ​​​​​​​

 

Well thank you !!…didn’t look up the C5 U codes so I’m assuming the OP meant a P0107 which would indeed be a MAP sensor DTC…maybe Midas got it wrong ??…just need the correct DTC posted.

 

After googling it, it said U0107 was the map sensor

I didn’t try to start it because the battery is weak already

The correct dtc is U0107

 

It can’t be a U0107…”communication” codes begin with U1XXX and not U0XXX…it would be a P0107…P meaning a POWERTRAIN code…where are you reading this DTC from ??…a scan tool or the cars DIC ??…how about a picture ??

 

 

That code is not on the list of C5 specific U codes that I looked up. The loss of communication codes were 10xx. The system wiring diagrams do not show a data line for the TAC module, but as I discovered the PCM does have a serial interface to the TAC module. So an easy thing to do is to check if the throttle plate moves when you press on the throttle pedal.

 

Turned the key on, no movement on the throttle body whatsoever

 

No movement of the TB blade would indeed produce reduced power!!!

 

Well that's a start. Next is to check for power and grounds at the TAC module. You can also check for voltages at the throttle body position sensor. There is 5v excitation from the TAC module to that sensor.

 

I’ll have to get back with you on that one. I’ve only got a volt meter at work and can’t bring it home 😅

 

ok check ignition fuse 17 on the toe board and ignition relay 42 under the hood.

 

The voltages from both tac sensors when backprobing the sensors at the trottlebody should behave like this when you press the pedal to the floor with ignition ON engine OFF