Open circuit at fuel voltage regulator ( where is it located )

Check out the link

https://www.google.com/search?q=2005+Ford+Five+Hundred+Limited+AWD.+Where+is+the+fuel+pressure+regulator+control+valve+circuit

..

2007 Chevrolet Silverado - 2WD or 4X4
2007 Chevrolet Silverado Classic - 4WD or 2WD . What size engine ?
Engine Controls and Fuel - 4.3L
Engine Controls and Fuel - 4.8L, 5.3L, and 6.0L
Engine Controls and Fuel - 6.6L (LBZ and LLY)
Engine Controls and Fuel - 8.1L

6.6 L
DTC P0191: Fuel Rail Pressure (FRP) Sensor Performance
The fuel rail pressure (FRP) sensor has a 5-volt reference circuit, a signal circuit, and a low reference circuit. The engine control module (ECM) monitors the voltage on the FRP sensor circuits. When the fuel pressure is high, the signal voltage is high. When the fuel pressure is low, the signal voltage is low. The fuel pressure regulator has a solenoid supply voltage circuit and a solenoid control circuit. The ECM controls the fuel pressure regulator , which regulates high pressure fuel that goes to the fuel injector rails and the injectors.

Your vehicle has no fuel pump relay . Has a fuel pump flow control module .
Fuel Pump Flow Control Module (FPCM)
The fuel pump flow control module (FPCM) is a serviceable GMLAN module. The FPCM receives the desired fuel pressure message from the engine control module (ECM) and controls the fuel pump located within the fuel tank to achieve the desired fuel pressure. The FPCM sends a PWM signal to the fuel pump, and pump speed is changed by varying the duty cycle of this signal.
Plus it has two fuel pumps !
The high pressure fuel pump (9) is a mechanical one cylinder design driven by an eccentric on the exhaust camshaft (1) of bank 2. High pressure fuel is regulated by the fuel rail pressure (FRP) regulator, which is a part of the high pressure fuel pump. The FRP regulator is a magnetic actuator which controls the inlet valve of the high pressure pump. The ECM provides battery voltage on the actuator high circuit and ground on the actuator low reference circuit. Both circuits are controlled by the ECM. When the ECM deactivates the FRP regulator, both circuits are disabled and the inlet valve is held open with spring pressure. When the ECM activates the FRP regulator, the low circuit driver connects the low reference circuit to ground and the high circuit driver pulse-width modulates (PWM) the high circuit. The ECM uses the camshaft and crankshaft position sensor inputs to synchronize the FRP regulator with the position of the eccentric on the camshaft. The ECM regulates fuel pressure by adjusting the portion of each pump stroke that provides fuel to the rail. The high pressure fuel pump also contains an integrated pressure relief valve.
Your best bet is have it towed to the dealer , you don't want to mess with the high pressure pump .
Pluse

The sensor and circuit would need to be tested.
The voltage signal back to the computer is below normal range.

Intermittent condition Restricted fuel supply line Fuel pump inlet strainer plugged Fuel pump module O2 sensor heater operation O2 sensor EVAP system operation O2 sensor signal circuit shorted to voltage O2 sensor signal circuit open TPS voltage greater than 0.92 volts with throttle closed Throttle position sensor sweep MAP sensor operation ECT sensor operation Engine mechanical problem Fuel filter/pressure regulator (high)

P1102O2S Heating Circuit Bank 1 Sensor 1 Voltage Too Low/Air Leak
P1105O2S Heating Circuit Bank 1 Sensor 2 Short To Positive P1107O2S Heating Circuit Bank 2 Sensor 1 Short To Positive P1110O2S Heating Circuit Bank 2 Sensor 2 Short To Positive P1113O2S Sensor Heater Resistance Too High Bank 1 Sensor 1 P1115O2S Sensor Heater Circuit Short To Ground Bank 1 Sensor 1
P1116O2S Sensor Heater Circuit Open Bank 1 Sensor 1
P1117O2S Sensor Heater Circuit Short To Ground Bank 1 Sensor 2
P1118O2S Sensor Heater Circuit Open Bank 1 Sensor 2
P1127Long Term Fuel Trim B1 System Too Rich
P1128Long Term Fuel Trim B1 System Too Lean
P1129Long Term Fuel Trim B2 System Too Rich
P1130Long Term Fuel Trim B2 System Too Lean
P1136Long Term Fuel Trim Add. Fuel B1 System Too Lean
P1137Long Term Fuel Trim Add. Fuel B1 System Too Rich
P1138Long Term Fuel Trim Add. Fuel B2 System Too Lean
P1139Long Term Fuel Trim Add. Fuel B2 System Too Rich
P1141Load Calculation Cross Check Range/Performance
P1144Mass Air Flow Sensor Open/Short To Ground.
P1145Mass Air Flow Sensor Short To Positive.
P1146Mass Air Flow Sensor Supply Voltage.
P1155Manifold Absolute Pressure Sensor Short To Positive.
P1156Manifold Absolute Pressure Sensor Open/Short To Ground. P1157Manifold Absolute Pressure Sensor Supply Voltage.
P1160Intake Air Temperature Sensor Short To Ground.
P1161Intake Air Temperature Sensor Open/Short To Positive. P1162Intake Air Temperature Sensor Short To Ground.
P1163Fuel Temperature Sensor Open/Short To Positive.
P1164Fuel Temperature Sensor Implausible Signal.
P1171Throttle Actuation Potentiometer Sign. 2 Range/Performance P1172Throttle Actuation Potentiometer Sign. 2 Signal Too Low P1173Throttle Actuation Potentiometer Sign. 2 Signal Too High P1176Rear O2S Correction
P1177O2 Correction Behind Catalyst B1 Limit Attained
P1196O2S Heater Circuit Bank 1 Sensor 1 Electrical Malfunction P1197O2S Heater Circuit Bank 2 Sensor 1 Electrical Malfunction P1198O2S Heater Circuit Bank 1 Sensor 2 Electrical Malfunction P1199O2S Heater Circuit Bank 2 Sensor 2 Electrical Malfunction P1213Injector Circuit Cylinder 1 Short To Positive
P1214Injector Circuit Cylinder 2 Short To Positive
P1215Injector Circuit Cylinder 3 Short To Positive
P1216Injector Circuit Cylinder 4 Short To Positive
P1217Injector Circuit Cylinder 5 Short To Positive
P1218Injector Circuit Cylinder 6 Short To Positive
P1225Injector Circuit Cylinder 1 Short To Ground
P1226Injector Circuit Cylinder 2 Short To Ground
P1227Injector Circuit Cylinder 3 Short To Ground
P1228Injector Circuit Cylinder 4 Short To Ground
P1229Injector Circuit Cylinder 5 Short To Ground
P1230Injector Circuit Cylinder 6 Short To Ground
P1237Injector Circuit Open Cylinder 1
P1238Injector Circuit Open Cylinder 2
P1239Injector Circuit Open Cylinder 3
P1240Injector Circuit Open Cylinder 4
P1241Injector Circuit Open Cylinder 5
P1242Injector Circuit Open Cylinder 6
P1245Needle Lift Sensor Short To Ground
P1246Needle Lift Implausible Signal
P1247Needle Lift Sensor Open/Short To Positive
P1248Start Of Cold Start Injector Control Difference
P1251Start Of Cold Start Injector Short To Positive
P1252Start Of Cold Start Injector Open/Short To Ground
P1255Engine Coolant Temperature Sensor Short To Ground
P1256Engine Coolant Temperature Sensor Open/Short To Positive P1300Misfire Detected, Fuel Level Too Low
P1250Fuel Level Too Low P1325Cyl. 1 Knock Control Limit Attained
P1326Cyl. 2 Knock Control Limit Attained
P1327Cyl. 3 Knock Control Limit Attained
P1328Cyl. 4 Knock Control Limit Attained
P1329Cyl. 5 Knock Control Limit Attained
P1330Cyl. 6 Knock Control Limit Attained
P1336Engine Torque Adaption At Limit
P1337CMP Sensor Bank 1 Short To Ground
P1338CMP Sensor Bank 1 Open Circuit Or Short To Positive P1340CKP/CMP Sensor Signals Out Of Sequence
P1341Ignition Coil Output Stage 1 Short To Ground
P1343Ignition Coil Output Stage 2 Short To Ground
P1345Ignition Coil Output Stage 3 Short To Ground
P1354Modulating Piston Displacement Sensor Electrical Circuit Malfunction
P1386Internal Control Module Knock Control Error
P1387Control Unit Internal Altitude Sensor
P1391CMP Sensor Bank 2 Short To Ground
P1392CMP Sensor Bank 2 Open Circuit/Short To Positive
P1393Ignition Coil Power Output Stage 1 Malfunction
P1394Ignition Coil Power Output Stage 2 Malfunction
P1395Ignition Coil Power Output Stage 3 Malfunction
P1401EGR Valve Power Stage Short To Ground
P1402EGR Vacuum Regulator Solenoid Valve Short To Positive P1403EGR System Control Difference
P1407EGR Temperature Sensor Signal Too Low
P1408EGR Temperature Sensor Signal Too High
P1410Tank Ventilation Valve Circuit Short To B+ P1420Secondary Air Injection Control Module Electrical Malfunction P1421Secondary Air Injection Valve Circuit Short To Ground P1422Secondary Air Injection Valve Circuit Short To B+ P1424Secondary Air Injection System Bank 1 Leak Detected P1425Tank Ventilation Valve Short To Ground P1426Tank Ventilation Valve Open Circuit P1432Secondary Air Injection Valve Open P1433Secondary Air Injection Pump Relay Circuit Open P1434Secondary Air Injection Pump Relay Circuit Short To Positive P1435Secondary Air Injection Pump Relay Circuit Short To Ground P1436Secondary Air Injection Pump Relay Circuit Electrical Malfunction P1440EGR Valve Power Stage Open P1441EGR Vacuum Regulator Solenoid Valve Open/Short To Ground P1450Secondary Air Injection System Circuit Short To Positive P1451Secondary Air Injection Circuit Short To Ground P1452Secondary Air Injection System Circuit Open P1471EVAP Control System LDP Circuit Short to Positive P1472EVAP Control System LDP Circuit Short To Ground P1473EVAP Control System LDP Open Circuit P1475EVAP Control System LDP Malfunction/Signal Circuit Open P1476EVAP Control System LDP Malfunction/Insufficient Vacuum P1477EVAP Control System LDP Malfunction P1478EVAP Control System LDP Clamped Tube Detected P1500Fuel Pump Relay Electrical Circuit Malfunction P1501Fuel Pump Relay Circuit Short To Ground P1502Fuel Pump Relay Circuit Short To Positive P1505Closed Throttle Position Does Not Close/Open Circuit P1506Closed Throttle Position Switch Does Not Open./Short To Ground P1512Intake Manifold Changeover Valve Circuit Short To Positive P1515Intake Manifold Changeover Valve Circuit Short To Ground P1516Intake Manifold Changeover Valve Circuit Open P1519Intake Camshaft Control Bank 1 Malfunction P1522Intake Camshaft Control Bank 2 Malfunction P1537Fuel Cut-off Valve Incorrect Function P1538Fuel Cut-off Valve Open/Short To Ground P1539Clutch Pedal Switch Signal Fault P1540VSS Signal Too High P1541Fuel Pump Relay Circuit Open P1542Throttle Actuation Potentiometer Range/Performance P1543Throttle Actuation Potentiometer Signal Too Low P1544Throttle Actuation Potentiometer Signal Too High
P1545Throttle Position Control Malfunction P1546Wastegate Bypass Regulator Valve Short To Positive P1547Wastegate Bypass Regulator Valve Short To Ground P1548Wastegate Bypass Regulator Valve Open P1549Wastegate Bypass Regulator Valve Open/Short To Ground P1550Charge Pressure Control Difference P1555Charge Pressure Upper Limit Exceeded P1556Charge Pressure Negative Deviation P1557Charge Pressure Positive Deviation P1558Throttle Actuator Electrical Malfunction P1559Idle Speed Control Throttle Position Adaption Malfunction P1560Maximum Engine Speed Exceeded P1561Quantity Adjuster Control Difference P1562Quantity Adjuster Upper Stop Value P1563Quantity Adjuster Lower Stop Value P1564Idle Speed Control Throttle Position Low Voltage During Adaption P1565Idle Speed Control Throttle Position Lower Limit Not Obtained P1568Idle Speed Control Throttle Position Mechanical Malfunction P1569Switch For CCS Signal Faulty P1580Throttle Actuator B1 Malfunction P1582Idle Adaptation At Limit P1600Power Supply Terminal No. 15 Low Voltage P1602Power Supply Terminal No. 30 Low Voltage P1603Internal Control Module Self Check P1606Rough Road Spec. Engine Torque ABS-ECU Electrical Malfunction P1611MIL Call-Up Circuit/TCM Short To Ground P1612Engine Control Module Incorrect Coding
P1613MIL Call-Up Circuit Open/Short To Positive P1616Glow Plug Indicator Lamp Short To Positive P1617Glow Plug Indicator Lamp Open/Short To Ground P1618Glow Plug Relay Short To Positive P1619Glow Plug Relay Open/Short To Ground P1624MIL Request Signal Active P1626Data Bus Drive Missing Command From M/T P1630Accelerator Pedal Position Sensor 1 Signal Too Low P1631Accelerator Pedal Position Sensor 1 Signal Too High P1632Accelerator Pedal Position Sensor 1/2 Supply Voltage P1633Accelerator Pedal Position Sensor 2 Signal Too Low P1634Accelerator Pedal Position Sensor 2 Signal Too High P1639Accelerator Pedal Position Sensor 1/2 Range Performance P1640Internal Control Module (EEPROM) Error P1648CAN-Bus System Component Failure P1649Data Bus Powertrain Missing Message From Brake Controller P1676Drive By Wire MIL Circuit Electrical Malfunction P1677Drive By Wire MIL Circuit Short To Positive P1678Drive By Wire MIL Circuit Short To Ground P1679Drive By Wire MIL Circuit Open Circuit P1681Control Module Programming Not Finished P1686Control Unit Error, Programming Error P1690MIL Malfunction P1691MIL Open Circuit P1692MIL Short To Ground P1693MIL Short To Positive P1778Solenoid EV7 Electrical Malfunction P1780Engine Intervention Readable P1851Data Bus Drive Missing Command From ABS P1854Drive Train CAN-Bus Inoperative

Read more at: https://www.obd-codes.com/trouble_codes/volkswagen/
Copyright OBD-Codes.com

The location of WHAT???

Diagnostic Test Code (DTC) P1250 is a manufacturer - specific code which has a general description of "Pressure Regulator Control (PRC) Solenoid Circuit Malfunction".

The PCM monitors input voltage at Pin number 44 when the ignition is turned on. DTC P1250 sets when less than .44 volts are present. The possible causes are:
> PRC Valve malfunction (open or shorted internally)
> Open or short circuit between the PRC valve and the PCM (control circuit)
> Open or short circuit in the solenoid ignition voltage supply circuit
> Failed PRC valve (stuck open)
> Malfunctioning PCM

(this is for others who may be viewing this problem)
P1594 = charging system voltage is too high
P0320 = crankshaft position sensor (CKP)/engine speed (RPM) sensor-circuit malfunction
P0463 = fuel level sensor circuit, high output
P1391 = intermittent loss of CMP (camshaft position) or CKP (crank position) sensor

Probably start with changing the crank sensor. But keep in mind that the high charging system voltage may be causing the other electrical sensor problems. The voltage regulator (probably located internally in the alternator) is not regulating voltage properly. So changing the alternator may be needed as well. Price the parts and start with replacing the less expensive first.

just a thought pull a coulpe of spark plugs see if there flooded also if you can scan the veh look at tps voltage now and look for cranking rpms should be around 240 rpms

not cpu.
Do not field out the field wire.
Is the alternator ight coming on?
If you rev engine, does charging system start working?
There is a resister wire that provides voltage to the field circuit. If the resister is bad, you will only get voltage to the field through the dash alt. light bulb when you push enough voltage through it.

I don''t have 1993, but here is 96:

Generator with Integral Rear Mount Regulator, Internal Fan Type With the key in the RUN position, voltage is applied through the charge indicator lamp I circuit to the voltage regulator. This turns the voltage regulator on, allowing current to flow from the battery sense A circuit to the generator field coil. When the engine (6007) is started, the generator (GEN) (10346) begins to generate alternating (AC) current which is converted to direct (DC) current by the rectifier internal to the generator. This current is then supplied to the vehicle's electrical system through the battery positive voltage (B+) terminal located on the rear of the generator. Once the generator begins generating current, a voltage signal is taken from the stator and fed back to the voltage regulator S circuit, turning off the charge indicator/lamp. With the system functioning normally, the generator output current is determined by the voltage at the A circuit. This voltage is compared to a set voltage internal to the voltage regulator, and the voltage regulator controls the generator field current to maintain proper generator output. The set voltage will vary with temperature and is typically higher in the winter than in the summer, allowing for better battery recharge. With the system functioning normally, the generator output current is determined by the voltage of the A circuit (battery sense voltage). The A circuit voltage is compared to a set voltage internal to the voltage regulator, which controls the generator field current to maintain proper output. The set voltage will vary with temperature and is typically higher in the winter than in the summer, allowing for better battery recharge in the winter and reducing the chance of overcharging the battery in the summer. A fuse link is included in the charging system wiring on all models. The fuse link is used to prevent damage to the wiring harness and generator if the wiring harness should become grounded, or if a booster battery with the wrong polarity is connected to the charging system.
-------------------------------------------------------------------------

• System Does Not Charge

• Loose or worn drive belt.
• Open/voltage drop in Circuit 38 (BK/O).
• Open/voltage drop in Circuit 36 (Y/W).
• Open/high resistance in Circuit 904 (LG/R).
• Damaged regulator.
• Damaged generator battery