feather12comp

I noticed the above codes after changing my throttle body. I reseated the connector, but no changes. Physical inspection of wiring does not reveal anything. Any suggestions on what to check?
U0101
- Faulty Transmission Control Module (TCM)
- TCM harness is open or shorted
- TCM circuit poor electrical connection
U0100
- Faulty Engine Control Module (ECM)
- ECM harness is open or shorted
- ECM circuit poor electrical connection

U0073
Control Module Communication Bus OFF

lordsmith

I am having the same problem, with a 2009 Impala,
Cant find a straight answer from anyone

Someone ,,,,,

tech2

U codes or undefined codes are usually set due to loss of communication of modules in a multiplexed bus configuration.

besides needing to know the model, year, engine, additional info such as:
-which modules will and will not communicate with the scan tool
-what modules are the codes set in
-what symptoms are you having
-are the codes active or history

lordsmith

I have a 2009 impala police model
3.9 6cyl

U 0101 No communication with TCM Speedo hops up and down , Slow take offs , hard shifts
P2544
ABS Light on Says all 4 wheels not reading

lordsmith

And codes are active ,, reset codes and they all returned

lordsmith

Now ,, what I have been reading was it might be a grounding issue, So I got another ground wire and ran it from the body grounding spot Directly to the engine block ,
It Ran better for a minute after resetting codes, ABS light went from solid to flashing every 30 seconds, then returned to solid.

Niky Nikolov

I'm having the same codes after cleaning of the throttle body. When I press the gas pedal the car start keeping 1500 rpm even if the pedal is released. I'm getting the same codes

Matthew Harris

I have the same problem with my chevy sonic and I took it in and my check engine light went off and everything to appear normal again but the codes were still in my computer. I have contact NHTSA to tell them because I have been having intermittent problems so if your having the same issue it's a safety issue report it in to the NHTSA maybe it could be a recall later

Ahmad Olayyan

i got the 3 messages at the same time many times.
they usually appears when:
1- turn off the engine after getting stuck in traffic jam for long time and A/C running in hot weather.
2- driving for long time in hot weather then turn off the engine.
3- engine rpms gets high many times.

The 3 cases i mentioned caused the 3 error codes to appear if turned off the engine without waiting the engine temprature to be cooled down.

i did notice that using my OBD2 scanner (ELM327), when engine temprature is above around 92c in hot weather, if engine turned off, temprature will go above 105c, some times you could even hear radiator water boiling sound,
and after that the issues appeared, i used to wait for the car for about 3-5 minutes to be cooled down before turning off engine.

i always have my OBD2 scanner in my car, once i feel gear shifting is hard and knocking, then i know the 3 codes appeared, easly i used to just clear the codes using OBD2 scanner, and every thing returns as it was.

it seems to be over-heat issue, but why? i have no idea!

solution is use OBD2 scanner to clear codes.
cheap scanner like ELM327 will do the job.

wawhipplejr

I read another posting stating that the alternator diode problems can cause these codes. I replaced my alternator. Problem solved, temporarily. All 3 U0073, U0100, U0101 came back.. I upgraded to a heavy duty alternator with lifetime warranty. Problem solved again, temporarily. Months later, yesterday, after my playing with the Parking Assist button, the Parking Assist light stayed on. Also, the U0073, U0100, U0101 codes popped up and would not clear. Parking sensors tested fine with the system beeping as I obstructed each of the 4 sensors with the truck running in reverse, kept stationary by a concrere parking divider. I figured the timing was likely related. This time I knew that my alternator was good. SOLUTION: I simply unplugged the electrical connection to the alternator, turned the ignition off for 5 minutes, cleared the 3 codes with my scanner. It resolved both my Parking Assist Off display and permanently cleared the U0073, U0100, U0101 codes.