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so I'm a new member hello to all! I am a bit of an amateur mechanic, but I have stumbled on a problem on my reliable coolbalt. I've had the car for couple months now have driven over 10,000 miles on it and the light comes on and my code reader says transmission control system along with shift solenoid b low circuit, note I have sent to mechanic and they did nothing for a month saying I need a whole new computer an ecu they must have thought I was dumb. I know it was a tcm it might need but wasn't for sure, I unplugged my battery ask night, started car drives like it should again and as soon as the light comes up later it acts funny a nd drives to third max and won't shift to 4th.. it's strange when I clear the code it drives normal and light comes on again and acts up won't go into 4th gear, any suggestions if it might be my tcm? bcm fuse maybe? I already ordered a ac delco tcm fir 100 bucks 12,000 mile warranty
 

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Well if code says it's a solenoid chances are it is. TCM seems to work good if it's able to consistently put out the same code for the bad solenoid. Obviously is communicating with ECM since it puts out a Check engine light request.

DTC P0700: Transmission Control Module (TCM) Requested MIL Illumination
 

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DTC P0976

Circuit Description
The 2-3 shift solenoid (SS) valve controls the transmission fluid pressure acting on the 1-2 and 2-3 shift valves to position the valves for the appropriate gear. The 2-3 SS valve is a normally open exhaust valve located on the lower control valve body. Ignition voltage is supplied to the solenoid. The transmission control module (TCM) commands the solenoid ON or OFF by providing a ground path. When the 2-3 SS valve is commanded ON, the TCM senses low voltage. When the 2-3 SS valve is commanded OFF, the TCM senses high voltage.

If the TCM detects a continuous open or short to ground in the 2-3 SS valve circuit, then DTC P0976 sets. DTC P0976 is a type A DTC.

DTC Descriptor
This diagnostic procedure supports the following DTC:

DTC P0976 2-3 Shift Solenoid (SS) Control Circuit Low Voltage

Conditions for Running the DTC
The engine is running for 5 seconds.

Conditions for Setting the DTC
The 2-3 SS valve feedback circuit indicates a continuous open or short to ground for 4.4 seconds.

Action Taken When the DTC Sets
• The TCM illuminates the malfunction indicator lamp (MIL).

• The TCM commands a soft landing to 2nd gear.

• The TCM commands maximum line pressure.

• The TCM freezes transmission adaptive functions.

• The TCM records the operating conditions when the Conditions for Setting the DTC are met. The TCM stores this information as Freeze Frame and Failure Records.

• The TCM stores DTC P0976 in TCM history.

---------- Post added at 11:18 AM ---------- Previous post was at 10:57 AM ----------

It could still be the "TCM", maybe the solenoid driver is bad. You will need somebody with a Tech II to command this solenoid. If you hear it click it's the transmission if you don't it's either or. Then you have to check at the TCM connector to see if "TCM" gives the command. If it does it's the solenoid if it doesn't it's the "TCM".
 
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