S-10 will not shift to low gear, works fine when manually shifted. It's an automatic transmission 2033 model. Think is an pressure switch but do not know which one, help.

If your 2009 Mercedes-Benz MP3 model truck's gear is not working in automatic mode and only working in manual mode, there could be a few potential causes. Here are a few steps you can try to troubleshoot and solve the issue:

1. Check the transmission fluid level: Make sure that the transmission fluid level is at the correct level and is not low. Low transmission fluid level can cause gear shifting problems.
2. Check the transmission filter: The transmission filter may be clogged, preventing the gears from shifting properly. Replace the filter if necessary.
3. Check the transmission control module (TCM): The TCM is responsible for controlling the automatic gear shifting. If it's malfunctioning, it can cause gear shifting problems.
4. Check the gear selector switch: The gear selector switch may be malfunctioning and preventing the gears from shifting properly.
5. Check the solenoids: The solenoids in the transmission may be malfunctioning and preventing the gears from shifting properly.
6. Check the transmission control linkages: The transmission control linkages may be damaged or disconnected, preventing the gears from shifting properly.

If you are not comfortable with checking these things, it's best to take the vehicle to a certified Mercedes-Benz mechanic to diagnose the problem. The technician will be able to identify the problem and repair it as necessary.
It's important to note that some of these steps may require special tools and knowledge of the vehicle's transmission system, so it's best to take it to a professional mechanic to avoid causing more damage.

DTC P0401 Exhaust Gas Recirculation (EGR) Flow Insufficient
Probably plugged passage's , not the EGR valve .
What type code reader are you using to read these codes ? I have factory service info. Doesn't show P0842 or P0642 , no such codes . You don't show what engine yours has , I'am assuming you have 3.5 L !
P0604
Control Module Random Access Memory (RAM)
PCM
DTC P0601, P0602, P0603, P0604, P0605, P0606, P0607, P1600, P1621, P1627, P1680, P1681, P1683, or P2610 in Engine Controls - 2.2L (L61)
or
DTC P0601, P0602, P0603, P0604, P0605, P0606, P0607, P1600, P1621, P1627, P1680, P1681, P1683, or P2610 in Engine Controls - 3.5L (LX9)

P0717
Input Speed Sensor Circuit Low Voltage
PCM
DTC P0717 in Automatic Transaxle - 4T40-E/4T45-E
P0741
Torque Converter Clutch (TCC) System - Stuck Off
PCM
DTC P0741 in Automatic Transaxle - 4T40-E/4T45-E
P0742
Torque Converter Clutch (TCC) System - Stuck On
PCM
DTC P0742 in Automatic Transmission - 4T40-E/4T45-E
P0748
Pressure Control (PC) Solenoid Control Circuit
PCM
DTC P0748 in Automatic Transmission - 4T40-E/4T45-E
P0751
1-2 Shift Solenoid (SS) Valve Performance - No First or Fourth Gear
PCM
DTC P0751 in Automatic Transmission - 4T40-E/4T45-E
P0752
1-2 Shift Solenoid (SS) Valve Performance - No Second or Third Gear
PCM
DTC P0752 in Automatic Transmission - 4T40-E/4T45-E
P0753
1-2 Shift Solenoid (SS) Control Circuit
PCM
DTC P0753 in Automatic Transmission - 4T40-E/4T45-E
P0756
2-3 Shift Solenoid (SS) Valve Performance - No First or Second Gear
PCM
DTC P0756 in Automatic Transmission - 4T40-E/4T45-E
P0757
2-3 Shift Solenoid (SS) Valve Performance - No Third or Fourth Gear
PCM
DTC P0757 in Automatic Transmission - 4T40-E/4T45-E
P0758
2-3 Shift Solenoid (SS) Control Circuit
PCM
DTC P0758 in Automatic Transmission - 4T40-E/4T45-E
P0815
Upshift Switch Circuit
PCM
DTC P0815 in Automatic Transmission - 4T40-E/4T45-E
P0816
Downshift Switch Circuit
PCM
DTC P0816 in Automatic Transmission - 4T40-E/4T45-E
P0826
Up and Down Shift Switch Circuit
PCM
DTC P0826 in Automatic Transmission - 4T40-E/4T45-E
P0973
1-2 Shift Solenoid (SS) Control Circuit Low Voltage
PCM
DTC P0973 in Automatic Transmission - 4T40-E/4T45-E
P0974
1-2 Shift Solenoid (SS) Control Circuit High Voltage
PCM
DTC P0974 in Automatic Transmission - 4T40-E/4T45-E
P0976
2-3 Shift Solenoid (SS) Control Circuit Low Voltage
PCM
DTC P0976 in Automatic Transmission - 4T40-E/4T45-E
P0977
2-3 Shift Solenoid (SS) Control Circuit High Voltage
PCM
DTC P0977 in Automatic Transmission - 4T40-E/4T45-E

Sometimes with code readers they get confused an just throw any old codes . Have it checked by someone with GM Tech 2 scan tool .

Automatic Transmission Shift Lock Control System
The automatic transmission shift lock control system is a safety device that prevents an inadvertent shift out of PARK when the engine is running. The driver must press the brake pedal before moving the shift lever out of the PARK position. The system consists of the following components:
• The automatic transmission shift lock control solenoid
• The automatic transmission shift lock control switch
With the ignition in the ON position, voltage is supplied to automatic transmission shift lock control switch. Voltage flows through the normally closed contacts of the automatic transmission shift lock control switch to the automatic transmission shift lock control solenoid. The automatic transmission shift lock control solenoid is permanently grounded. This energizes the automatic transmission shift lock control solenoid causing the transmission shift lever to be physically locked in the PARK position. When the brake pedal is pressed the contacts in the automatic transmission shift lock control switch open, de-energizing the automatic transmission shift lock control solenoid. This allows the shift lever to be move out of the PARK position.

Circuit Description
The transmission range (TR) switch is part of the park/neutral position (PNP) and back-up lamp switch assembly, which is externally mounted on the transmission manual shaft. The TR switch contains four internal switches that indicate the transmission gear range selector lever position. The powertrain control module (PCM) supplies ignition voltage to each switch circuit. As the gear range selector lever is moved, the state of each switch may change, causing the circuit to open or close. An open circuit or switch indicates a high voltage signal. A closed circuit or switch indicates a low voltage signal. The PCM detects the selected gear range by deciphering the combination of the voltage signals. The PCM compares the actual voltage combination of the switch signals to a TR switch combination chart stored in memory.

These are all electronically controlled , yur best bet would be to take your vehicle to the dealer .

i take it is a automatic check gearbox transmission fluid or the torque converter may be at fault

PRND321 Display
The instrument panel cluster (IPC) displays the selected gear position as determined by the engine control module (ECM). The IPC - instrument panel cluster receives a serial data message from the ECM indicating the gear position. The PRND321 display blanks if:
?€¢
The ECM detects a malfunction in the transmission range switch circuit.

?€¢
The IPC detects a loss of serial data communications with the ECM. The automatic transmission shift lock control system is a safety device that prevents an inadvertent shift out of PARK when the engine is running. The driver must press the brake pedal before moving the shift lever out of the PARK position. The system consists of the following components:
?€¢
The automatic transmission shift lock control solenoid

?€¢
The automatic transmission shift lock control switch

With the ignition in the ON position, voltage is supplied to automatic transmission shift lock control switch. Voltage flows through the normally closed contacts of the automatic transmission shift lock control switch to the automatic transmission shift lock control solenoid. The automatic transmission shift lock control solenoid is permanently grounded. This energizes the automatic transmission shift lock control solenoid causing the transmission shift lever to be physically locked in the PARK position. When the brake pedal is pressed the contacts in the automatic transmission shift lock control switch open, de-energizing the automatic transmission shift lock control solenoid. This allows the shift lever to be move out of the PARK position.
The transmission range (TR) switch is part of the park/neutral position (PNP) and backup lamp switch assembly, which is externally mounted on the transmission manual shaft. The TR switch contains four internal switches that indicate the transmission gear range selector lever position. The PCM supplies ignition voltage to each switch circuit. As the gear range selector lever is moved, the state of each switch may change, causing the circuit to open or close. An open circuit or switch indicates a high voltage signal. A closed circuit or switch indicates a low voltage signal. The PCM detects the selected gear range by deciphering the combination of the voltage signals. The PCM compares the actual voltage combination of the switch signals to a TR switch combination chart stored in memory.
You need a Tech2 scan tool to diagnose this problem ! possible range sensor !

my guess is its not electric shifted, (what trans model is it)
so step 2 in the FSM book says.... and i paraphrase
step1 is stall test (my guess passes in 1st and reverse)
step 2, line pressure test?
if that fails, tranny is bad.

The short answer, yes. M46 models with the type J or P overdrive (depending on year and market) require a certain level of oil in the overdrive. Additionally, the overdrive is a lot like a standard automatic transmission with one gear range in theory of operation. Therefore, the hydraulic properties of said transmission do come into play here, line pressure, shifting pressure, accumulator and piston function all work together to engage or disengage the unit. Always ensure the unit is disengaged before downshifting and of course, shifting into low reverse.

Here is what the service manual says about the EPC solenoid, the processor looks at allot of different inputs to command the solenoids, such as Throttle Position Sensor, Vehicle Speed Sensors, Transmission Range Sensor and RPM signal, The PCM controls the shift patterns for the transmission. Electronic Pressure Control (EPC) Solenoid
The electronic pressure control (EPC) solenoid is located on the main control valve body and is controlled by the PCM. The EPC controls line pressure used to apply and release clutches and bands in the transmission.
The 2-3 shift solenoid is located on the main control valve body and is switched on and off by electrical signals from the PCM. The 2-3 shift solenoid activates the 2-3 shift valve which controls the automatic shifting between second and third gear. Second gear is established when the 2-3 shift solenoid is switched on. The 2-3 shift solenoid is switched off when vehicle speed increases and requires a second to third gear upshift.
The 3-4 shift solenoid is located on the main control valve body and is switched on and off by electrical signals from the PCM. The 3-4 shift solenoid activates the 3-4 shift valve which controls the automatic shifting between third and fourth gear. Third gear is established when the 3-4 solenoid is switched off. The 3-4 shift solenoid is switched on when vehicle speed increases and requires a third to fourth gear upshift.

Yes, many. The automatic transmission shifts through gears relatively similar to an manual transmission, except it does the work for you. Kind of like one of the auto shift 10 speed bicycles shifts as you reach the maximum speed for the gear it's in. As opposed to a regular 10 speed bicycle that has to be shifted manually with the lever.

not sure if this is the answer yet but i have the same problem with the same codes i work at an auto parts store and a few of the techs that are customers have lead me in the direction of changing the ignition switch, i am doing it today will let you know if it solves the problem