ellamejia2001

We are working on a 05 Corvette Base 6.0L. Customer complaints: CEL ON, trac and anti theft light on, speedometer not working and stuck on second gear (limp mode).

Code present: Pulled using LAUNCH X431 Pad (with new updates)
U0101 LOST COMM WITH TCM

C0035 LEFT FRONT WHEEL SPEED SENSOR

C0040 RIGHT FRONT WHEEL SPEED SENSOR

C0281 DYNAMIC REAR PROPORTIONING PERFORMANCE

C0242 PCM INDICATED TCM MALFUNCTION

C0561 SYSTEM DISABLE INFORMATION STORED INVALID SERIAL DATA RECEIVED

U2100 CONTROL AREA NETWORK
COMMUNICATION

WORKED PERFORMED:

CHECKED AND TESTED BATTERY. NO START (READING AT 12V) NORMAL

ONCE VEHICLE HAS STARTED AND USING ALL THE ACCESSORIES. VOLTAGES GOES DOWN 12.6-12.7V. A MINUTE OF RUNNING ON IDLE.

THEN REPLACED ALTERNATOR. IT WAS "FINE" TEST DRIVE VEHICLE. VOLTAGE WAS CORRECT. BUT THEN WE MOVED ON CHECKING THE TRANSMISSION PLUG/CONNECTOR (FOR THE TCM ISSUE) EVERYTHING IS "FINE" WITH PLUG/CONNECTOR BUT AFTER MOVING THE PLUG/CONNECTOR, IT STARTED AGAIN. VOLTAGE GOES DOWN AND STARTING AGAIN FROM THE BEGINNING.

WARRANTED THE ALTERNATOR BUT NO USE.

REPLACE TCM WITH OE PART (REQUIRES PROGRAMMING AT THE DEALER) NOTE: WE DIDN'T HAVE IT PROGRAMMED. WE HAVE THE JBOX AND PURCHASED PROGRAMMING SOFTWARE FROM AC DELCO SITE.

AFTER LOADING PROPER PROGRAMMING SOFTWARE (WITH THE HELP OF THE TECHLINE GUY) I WASN'T ABLE TO PROGRAMMING TCM. AFTER TECHLINE ACCESSED MY COMPUTER AND PROGRAMMING SOFTWARE, EVERTHING ON MY END WAS "GOOD". BUT TCM IS NOT COMMUNICATING WITH US.

AFTER THAT THE CAR HAS TAKEN A ****. ECM NO COM. TCM NO COM.

WIRING HAS BEEN CHECKED (HEAD TECH FOR ME AND A OUTSIDE SOURCE). FUSES ARE OKAY.

VEHICLE STARTS. VEHICLE IS ABLE TO SHIFT INTO GEARS. BUT ALL THE LIGHTS THAT I MENTIONED ARE STILL ON.

THANK YOU IN ADVANCE.

EVRose

Sounds like a bad ground somewhere.

Patsgarage

I had an 05 Cobalt w/ similar problems including the TCM code. Tried a replacement TCM w/o success. Ended up being a bad ground at the trans. Get a pinout for the TCM and check for ground at the plug.

ellamejia2001

Thanks for the reply. It was a ground problem

EVRose

ellamejia2001

Corvette was ready to release today. I was going through the vehcile for final inspection and decided to start her up. She was sitting pretty under the sun (getting her tan on). Started her up and then my jaw fell to the floor She is back where we started Run the diagnostic on her. And all the symptoms are back. Rechecked wiring, modules and fuses. Reset system and let her stayed inside the shop to cool her down. Test drive was "FINE"! EVERYTHING IS FINE! But she DO NOT LIKE THE SUN

EVRose

I wouldn't know where to begin with that one. Error codes, but only when it's sunny.

Patsgarage

Where/how did you find the bad ground ? How was it repaired ?

ellamejia2001

When EVRose suggested a ground. My tech checked the AT plug/connector. Checked and rechecked the wiring harness (starts at ECU). Then he noticed that when he started to check and unplug the TCM (located near the right fender) the voltage goes up and down. So he slowly separated and rewired everything again. VOILA! Installed new TCM. Reprogrammed. Reflashed system (just to make sure). Test drive for 30 minutes. Had the A Okay! Client came, we showed him the progress. He was happy, I was happy (mama gets paid!) But for some odd reason my tech suggested to stay for one more day. No problem. Morning rolled along, she was still fine. Test drive for another 45 min. still fine. Called client. Car went to hand wash (cause we don't do drive thru washes too many issues). We got her back, parked her out front and waited. SoCal weather was 105 no shade out front. One more walk around just to make sure. Then BOOM!

Patsgarage

When you say "rewired" what exactly do you mean ? Did the ground wire from the TCM plug go to a ground lug where it was combined with other wires ? If so, did he cut off the ring terminal and soldier a new one in its place ? I have seen terminals w/ multiple wires look good, but have weak connections where they are crimped/ soldired in place. It still sounds like an electrical problem. Also where was the voltage being measured when it went up and down ? At the TCM connector (power in to ground out) or at the battery ?

RJRSW

Classic corvette battery going bad symptoms. Replace the battery if the battery has gone dead a couple of times it needs to be replaced.