Mechanics

TRANSMISSION

2004 Saturn Ion • Automatic • 70,000 miles

My 2004 Saturn Ion is driving in Limp mode. A friend ran a computer diagnostic and it returned the codes P0700, P0977, and P0983. He erased the codes and 0700 and 0977 returned immediately. He thinks it is something to do with the trans computer and finally had to refer me to a transmission specialist. Can you offer any insight as to the actual problem and a rough cost estimate before I go to get this fixed?
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Chawthorne4
April 19, 2011.



P0700 is not any component fault but rather an indication of the transmission-fault reporting to the engine computer.

DTC P0977, a fault with the shift solenoids.

Circuit Description
The 2-3, 3-4 shift solenoid (SS) valve (S2) controls transmission fluid pressure acting on the M2 shift valve to position the valve for the appropriate gear. The 2-3, 3-4 SS valve (S2) is a normally open exhaust valve located on the front control valve body. The solenoid is case grounded. The output driver module (ODM), within the transmission control module (TCM), commands the solenoid ON or OFF by providing voltage. When the 2-3, 3-4 SS valve (S2) is commanded ON, the TCM senses high voltage. When the 2-3, 3-4 SS valve (S2) is commanded OFF, the TCM senses low voltage.

If the TCM detects a continuous open or short to voltage in the 2-3, 3-4 SS valve (S2) circuit, then DTC P0977 sets. DTC P0977 is a type A DTC.

Conditions for Running the DTC

• The system voltage is 8-18 volts.
• The engine run time is greater than 5 seconds.
• Trans. Protection Mode is OFF.
• The TCM has commanded the 2-3, 3-4 SS valve OFF.

Conditions for Setting the DTC
The 2-3, 3-4 SS valve (S2) feedback circuit indicates a continuous open or short to voltage for 0.5 seconds.

Action Taken When the DTC Sets
• The TCM requests the engine control module (ECM) to illuminate the malfunction indicator lamp (MIL).

• The TCM turns the Trans. Protection Mode ON. When the Trans. Protection Mode is ON, the following conditions occur: ? The transmission will operate in 5th gear when the transmission is shifted into D or I range and 2nd gear when shifted into L range.
? The line pressure is at maximum.
? The torque converter clutch (TCC) is disabled.
? The TCM freezes the transmission adaptive functions.
? The ECM records the operating conditions when the Conditions for Setting the DTC are met. The ECM stores this information as Freeze Frame and Failure Records.

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

• The TCM stores DTC P0977 in TCM history.

The problem could be due to loose, bad or contaminated wiring or grounding circuits. Alternatively it ould be faulty shift solenoids, a bad valve body or even an indication the transmission needs to be replaced. The price is going to range from a couple hundreds ranging into the thousand and without any detailled diagnosis, it is not possibe to provide any actual costing.

At the transmission, check the wire harness and connectors for clean and tight connections and repair if necessary. Quite often it is the wirings or failed solenoids, which would be the cheapest thing that can happen with the fault.

KHLow2008
Apr 19, 2011.