Error codes What is "DTC detected in ECM(engine control modual) PCM (?) and any idea on what I need to do. My "check gages" light is on and I keep getting told the error code mean different things. P0523, P1682, P1693. Do you know where these sensors are located or how I can find out? This is a 1999 Dodge Ram 3500 cummins diesel.

'year make model' in all question please.

P0203 OBD-II Trouble Code: Injector Circuit Malfunction

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The P0203 is a diagnostic trouble code that is set when the engine control module (ECM) has detected a fault in the injector circuit for cylinder 3. The ECM ...

P0203 Code: Injector Circuit / Open - Cylinder 3 - CarParts.com

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Diagnostic trouble code (DTC) P0203 stands for "Injector Circuit/Open - Cylinder 3." The powertrain control module (PCM) may set this code if it ...
Nov 11, 2021 · Uploaded by The Flat Rate Mechanic

Error Code P0203: Cylinder 3 Injector Circuit Malfunction

https://autoservicecosts.com > obd2-codes > p0203
Error Code P0203 is defined as Cylinder 3 Injector Circuit Malfunction. This code means the PCM (powertrain control module, also known as ECM or engine ..

DTC P1637

The powertrain control module (PCM) / engine control module (ECM) uses the charge indicator control circuit, and the generator 2 turn on signal circuit on diesels with dual generators, to control the generator(s). A high side driver within the PCM/ECM allows the PCM/ECM to turn the generator ON and OFF. When generator operation is desired, the PCM/ECM sends a 10-11 volts-volt signal to the voltage regulator via the generator turn on signal circuit. This causes the voltage regulator to begin controlling the generator field circuit. Once the generator is enabled by the PCM/ECM, the voltage regulator controls generator output independently of the PCM/ECM. Under certain operating conditions, the PCM/ECM can turn OFF the generator by turning OFF the voltage on the charge indicator control circuit. The PCM/ECM has fault detection circuitry which monitors the state of the charge indicator control circuit. If the fault detection circuit senses a voltage other than what is expected, the charge indicator will turn ON and this DTC will set. The voltage regulator also contains fault detection circuitry. If the regulator detects a problem, the regulator will ground the charge indicator control circuit, pulling the voltage low. This also causes the charge indicator to turn ON and the PCM/ECM to set the DTC.

What engine is in your truck ?

DTC P1638

The powertrain control module (PCM) uses the generator field duty cycle signal circuit to monitor the duty cycle of the generator. The generator field duty cycle signal circuit connects to the high side of the field winding in the generator. A pulse width modulated (PWM) high side driver in the voltage regulator turns the field winding ON and OFF. The PCM uses the PWM signal input to determine the generator load on the engine. This allows the PCM to adjust the idle speed to compensate for high electrical loads.
The PCM monitors the state of the generator field duty cycle signal circuit. When the key is in the RUN position and the engine is OFF, the PCM should detect a duty cycle near 0 percent. However, when the engine is running, the duty cycle should be between 5-100 percent. The PCM monitors the PWM signal using a key ON test and a RUN test. During the tests, if the PCM detects an out of range PWM signal, DTC P1638 will set. When the DTC sets, the PCM will send a class 2 serial data message to the IPC to illuminate the charge indicator.

Did you check the fuse that supply's battery voltage to pin # 16 at the DLC - diagnostic link connector ? That's where you plug your code reader in . The lighter fuse - 15 amp located in the under hood fuse box supply's battery voltage to pin #16 . The fuel gauge not working could be any one of a number of thing's , without testing an checking for DTC'S - diagnostic trouble code's I would only be guessing . Checking code's in the instrument cluster an PCM should be done by a qualified repair shop. The fuel level sending unit in the fuel tank is a direct input to the PCM/ECM - engine computer , the PCM / ECM sends this info too

The instrument panel cluster (IPC) displays the fuel level as determined by the powertrain control module (PCM)/engine control module (ECM). The IPC receives a GMLAN message from the body control module (BCM) indicating the fuel level volume. The fuel gage defaults to empty (E) if:
• The PCM/ECM detects a malfunction in the fuel level sensor circuit.
• The IPC detects a loss of GMLAN communications with the BCM.
When the fuel level is less than a certain low percentage, LOW FUEL message displays in the driver information center (DIC).

Odometer
The vehicle odometer is calculated and stored electronically in the body control module (BCM) and is sent via GMLAN to the instrument panel cluster (IPC) for display. The BCM calculates and stores the mileage based on the vehicle speed GMLAN message from the powertrain control module (PCM)/engine control module (ECM). The IPC displays the season odometer information from the BCM in the driver information center (DIC). The odometer will display error if the IPC detects an invalid odometer data from the BCM. After an invalid odometer data is received from the BCM, the IPC will display the last known odometer reading for 1.5 seconds before error is displayed in the DIC.

These can set a few different DTC'S

DTC B0158
DTC B2961
DTC P0461 (2.0L and 2.2L)
DTC P0461 (2.4L)
DTC P0462 (2.0L and 2.2L)
DTC P0462 (2.4L)
DTC P0463 (2.0L and 2.2L)
DTC P0463 (2.4L)
DTC P0464
DTC P0520


So , i suggest you take your vehicle to a qualified repair shop.

Did you test the electrical circuit's ? Have a scan tool hooked up ? Did you have a qualified repair shop check it out ?
When the engine is running, the generator control signal is sent to the generator from the engine control module (ECM)/powertrain control module (PCM), turning on the regulator. The generator's voltage regulator controls current to the rotor, thereby controlling the output voltage. The rotor current is proportional to the electrical pulse width supplied by the regulator. When the engine is started, the regulator senses generator rotation by detecting AC voltage at the stator through an internal wire. Once the engine is running, the regulator varies the field current by controlling the pulse width. This regulates the generator output voltage for proper battery charging and electrical system operation. The generator F terminal is connected internally to the voltage regulator and externally to the PCM. When the voltage regulator detects a charging system problem, it grounds this circuit to signal the PCM that a problem exists. The PCM monitors the generator field duty cycle signal circuit. The system voltage sense circuit receives B+ voltage that is Hot At All Times through the ECM/TCM fuse in the underhood junction block. This voltage is used by the regulator as the reference for system voltage control.
This vehicle uses Class II and controller area network (CAN) communications. The ECM/PCM are CAN and the body controller systems are Class II. The body control module (BCM) acts as the gateway between the different communication protocols. The ECM/PCM requests the battery lamp on the CAN communication line and then the BCM sends a request to the IPC for lamp illumination.
The ECM/PCM will request the battery lamp on under the following conditions:
• The ECM/PCM interprets the ignition is in the accessory position.
• The ECM/PCM is in the RUN power mode with the engine not running.
• Generator L terminal fault has been detected.
• Generator F terminal fault has been detected.
If the generator is not charging, it pulls the F terminal low causing an F terminal fault. Low voltage threshold is 10.5 volts for 4 minutes and engine at least 1,300 RPM. High threshold is 18 volts for 5 minutes.


https://www.motor.com/magazinepdfs/042010_09.pdf

Do you know what DTC'S diagnostic trouble codes are ?
DTC B1325
DTC B1327
DTC B1328
DTC P0562
DTC P0563
DTC P0615
DTC P0621
DTC P0622
These are all for the charging system .

NO , there is not a fuse just for those two thing's ! There are two power supply's for the whole insturment cluster . You could need a new cluster or the ECM isn't sending this info. to the cluster . Could have DTC'S - diagnostic trouble codes stored in the PCM or the insturment cluster . Without knowing how this works (insturment cluster gets it's info.) Your best bet , take it to a qualified repair shop that has the knowledge and test equipment to diagnose this problem.
Engine Oil Pressure Gage
The instrument panel cluster (IPC) displays the engine oil pressure as determined by the engine control module (ECM). The IPC receives a serial data message from the ECM indicating the engine oil pressure. The engine oil pressure gage defaults to 0 psi (0 kPa) or below if:
• The ECM detects a malfunction in the engine oil pressure sensor circuit.
• The IPC detects a loss of serial data communications with the ECM.
For the 4.2L LL8, the ECM uses an engine oil switch that is open when the oil pressure is normal and closed when the oil pressure is low. At normal pressure, the engine oil pressure gage will display 275 kPa (40 psi). At low pressure, the gage will go to 0 kPa and the low pressure warning will be displayed in the driver information center (DIC). At high pressure, the gage will display 551 kPa (80 psi). Any values between these three values are calculated values determined by the ECM.

Voltmeter
The instrument panel cluster (IPC) displays the vehicle voltage based on the information from the body control module (BCM). The IPC uses the serial data information from the BCM to provide a voltage level indication on the voltmeter.

DTC P0521: Engine Oil Pressure (EOP) Sensor Performance

DTC P0522 Engine Oil Pressure (EOP) Sensor Circuit Low Voltage
DTC P0523 Engine Oil Pressure (EOP) Sensor Circuit High Voltage

Volt Gage Inaccurate or Inoperative
2
Install a scan tool.
Turn the ignition ON, with the engine OFF.
With the scan tool, perform the instrument panel cluster (IPC) gauges output control.
Does the volt gauge move up and down when commanded?

Hi Julia , why do you believe you need to find the temp sensor ? Temp gauge not working ? The cooling Temp sensor is a input to the PCM / ECM - engine computer .
Engine Coolant Temperature Gage
The instrument panel cluster (IPC) displays the engine coolant temperature (ECT) as determined by the powertrain control module (PCM) or the powertrain control module (PCM). The IPC receives a class 2 message from the PCM indicating the ECT. The range on the ECT gage is between 60-125°C (140-260°F). The ECT gage defaults to 60°C (140°F) or below if the PCM detects a malfunction in the ECT sensor circuit. Refer to Cooling System Description and Operation .
Would have DTC- diagnostic trouble code stored in Instrument cluster or the check engine light would be on . Before replacing a part you may not need take it to a qualified repair shop to have it diagnosed .

Check and or test fuel gauge sending unit and the gauge . Videos on youtube showing how to . Also i would have the vehicle checked for DTC's - diagnostic trouble codes . You may want to think about taking to a qualified repair shop .

Fuel Gage
The instrument panel cluster (IPC) displays the fuel level as determined by the engine control module (ECM). The IPC receives a serial data message from the BCM indicating the fuel level percent. The fuel gage defaults to empty if:
• The ECM detects a malfunction in the fuel level sensor circuit.
• The IPC detects a loss of serial data communications with the BCM.
• The BCM detects a loss of serial data communications with the ECM.

DTC P0461
The fuel level sender changes resistance based on fuel level. The powertrain control module (PCM) monitors the signal circuit of the fuel level sender in order to determine fuel level. When the fuel tank is full, the sender resistance is low and the PCM senses a low signal voltage. When the fuel tank is empty, the sender resistance is high and the PCM senses a high signal voltage. The PCM uses the signal circuit of the fuel level sender in order to calculate the total remaining fuel percent in the tank. The PCM sends the fuel level percent via the class 2 serial data circuit to the instrument cluster in order to control the fuel gage. The fuel level information is also used for misfire and evaporative emission (EVAP) diagnostics.

DTC P0462 Fuel Level Sensor Circuit Low Voltage
DTC P0463 Fuel Level Sensor Circuit High Voltage

Before doing something drastic ,have it checked out for DTC'S - diagnostic trouble codes . It may not be the anti-theft system ,gauges going flat would be more like a communication problem between modules . PCM / BCM / instrument cluster etc.. That also could cause theft light coming on . If your not sure what to look for ,take it to a ASE certified professional . You may render your vehicle useless if you don't know what your doing .
Serial Data Power Mode Master
On vehicles that have several control modules connected by serial data circuits, one module is the power mode master (PMM). On this vehicle, the PMM is the body control module (BCM). The PMM receives 3 discrete ignition switch signals to differentiate which power mode will be sent over the Serial Data circuits. The 3-wire Ignition Switch table below illustrates the state of these inputs in correspondence to the ignition switch position:
Serial Data Messages The modules that depend exclusively on serial data messages for power modes. stay in the state dictated by the last valid PMM message until they can check for the engine run flag status on the serial data circuits. If the PMM fails, the modules monitor the serial data circuit for the engine run flag serial data. If the engine run flag serial data is True, indicating that the engine is running, the modules fail-safe to RUN. In this state, the modules and their subsystems can support all operator requirements. If the engine run flag serial data is False, indicating that the engine is not running, the modules fail-safe to OFF-AWAKE. In this state, the modules are constantly checking for a change status message on the serial data circuits and can respond to both local inputs and serial data inputs from other modules on the vehicle.
Indicators and Warning Messages
Refer to Indicator/Warning Message Description and Operation .
Engine Coolant Temperature Gage
The instrument panel cluster (IPC) displays the engine coolant temperature as determined by the powertrain control module (PCM) or the engine control module (ECM). The IPC receives a serial data message from the PCM/ECM indicating the engine coolant temperature. The engine coolant temperature gage defaults to 38?°C (100?°F) if:
?€¢
The PCM/ECM detects a malfunction in the engine coolant temperature sensor circuit.

?€¢
The IPC detects a loss of serial data communications from the BCM.

Fuel Gage
The instrument panel cluster (IPC) displays the fuel level as determined by the powertrain control module (PCM) or the engine control module (ECM). The IPC receives a serial data message from the body control module (BCM) indicating the fuel level. The fuel gage defaults to E (empty) if:
?€¢
The PCM/ECM detects a malfunction in the fuel level sensor circuit.

?€¢
The IPC detects a loss of serial data communications from the BCM.

When the fuel level is less than 14 percent, the low fuel indicator illuminates.
Odometer
The instrument panel cluster (IPC) contains a season odometer and a trip odometer. Momentarily press the trip/reset switch in order to toggle between the season odometer and the trip odometer. Press the trip/reset switch for greater than 2 seconds, while the trip odometer is displayed, in order to reset the trip odometer. The odometer is calculated and stored electronically in the body control module (BCM). The BCM uses the vehicle speed information from the powertrain control module (PCM) to calculate the odometer. The odometer displays 'error' if an internal IPC memory failure is detected. The IPC stores a backup copy of the odometer value incase the IPC stops receiving a valid odometer value from the BCM.
Speedometer
The instrument panel cluster (IPC) displays the vehicle speed based on the information from the ECM/PCM. The IPC receives the vehicle speed information from the BCM via the serial data circuit. The speedometer defaults to 0 kmh (0 mph) when the following occurs:
?€¢
The powertrain control module (PCM) or the engine control module (ECM) detects a malfunction in the vehicle speed sensor circuit.

?€¢
The IPC detects a loss of serial data communication from the BCM.

Tachometer
The instrument panel cluster (IPC) displays the engine speed as determined by the powertrain control module (PCM) or the engine control module (ECM). The IPC receives a serial data message from the body control module (BCM) indicating the engine speed. The tachometer will default to 0 RPM if:
?€¢
The PCM/ECM detects a malfunction in the engine speed sensor circuit.

?€¢
The IPC detects a loss of serial data communication from the BCM.

Depends on model. http://www.obd-codes.com/p1605

It could be the electronic power steeirng module . With the gauges dropping out like that , the module could be bring down the data bus . Don't know how much you know about automotive electronic's an how the insturment cluster know's what speed to set speedo at an how full fuel gauge is an rpm on the tach .
Speedometer
The instrument panel cluster (IPC) displays the vehicle speed based on the information from the engine control module (ECM)/powertrain control module (PCM). The ECM/PCM calculates the vehicle speed based on the class 2 message indicating the wheel reference speed from the electronic brake control module (EBCM) if:
• The ECM/PCM detects a malfunction in the vehicle speed sensor circuit.
• The IPC detects a loss of class 2 communications with the ECM/PCM.
The speedometer defaults to 0 km/h (0 mph) if the IPC detects a loss of class 2 communications with both the ECM/PCM.

012 GM Class II Communications

Checking the vehicle modules for DTC'S - diagnostic trouble codes is the first place to start .
The Power Steering Control Module (PSCM) receives a class 2 vehicle speed message from the Engine Control Module (ECM) via a class 2 serial data circuit. The PSCM uses this vehicle speed message, and other inputs, to determine the desired amount of steering assist.
DTC C0000
DTC C0475
DTC C0476
DTC C0545
DTC C0847
DTC C0848
DTC C0896
DTC C0899
DTC C0900

your best bet ,take it to a qualified GM repair shop .