DTC P1433 Fuel Pressure Sensor Circuit High Voltage. GMC Truck GMC K Pickup

For 1990-2009 cars only

Makes 🢒 GMC_Truck 🢒 1999 🢒 GMC K Pickup - 4WD (CNG) 🢒 Engine 🢒 Engine Controls - 5.0L and 5.7L 🢒 DTC P1433 Fuel Pressure Sensor Circuit High Voltage

Engine Controls Components
Engine Controls Schematics
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice
Handling ESD Sensitive Parts Notice

Circuit Description

The Fuel Pressure Sensor (FPS) is a potentiometer. The AF ECU supplies about 5 volts on the FPS sensor reference voltage circuit. The AF ECU also supplies a ground circuit to the FPS sensor. When fuel level/tank pressure is full the FPS signal voltage rises to 4.1 volts. As fuel level/tank pressure decreases to empty, the FPS signal voltage drops to around 0.5 volts. The AF ECU monitors the FPS signal circuit voltage and the Fuel Temperature Sensor (FTS) and determines the amount of fuel within the fuel tank.

This DTC is used to indicate a FPS sensor signal voltage that is above the normal operating range of the sensor.

Conditions for Running the DTC

•	The engine is operating on alternative fuel.

•	The Fuel Temperature Sensor is less than 30°C.

Conditions for Setting the DTC

The AF ECU monitors an FPS signal voltage of greater than 4.70 volts for at least 1 second continuously.

Action Taken When the DTC Sets

•	The AF ECU will illuminate the MIL and store the DTC as History during ONE drive trip in which the diagnostic runs and fails.

•	The AF ECU will record operating conditions at the time the DTC sets. This information will be stored as Freeze Frame data.

Conditions for Clearing the MIL/DTC

•	The Last Test Failed status will clear when the DTC runs and passes.

•	The AF ECU will turn OFF the MIL after 3 consecutive drive trips that the DTC runs and passes.

•	The History status will clear after 40 consecutive WARM-UP cycles with NO failures of ANY DTC.

•	All DTC Information can be cleared using a scan tool.

•	Interruption of Control Module (AF ECU / VCM / PCM or ECM) power or ground MAY clear DTC Information. Clearing DTC Information with this method is inconsistent and should not be performed.

Diagnostic Aids

Fault Not Present

Fault Not Present indicates the condition that caused the DTC to set is intermittent and not currently present. Refer to Intermittent Conditions Symptom diagnosis for additional information. If any additional DTCs were stored proceed to the applicable DTC table in the order stated in the OBD System Check.

Test Description

The number(s) below refer to the step number(s) on the diagnostic table.

This step determines if the failure condition is present.

This step determines if an open Sensor Ground circuit condition is present. Since the FPS and FTS share a Sensor Ground, and open condition between the splice and the AF ECU would cause both signal circuits to indicate high voltage.

This step determines if an open or shorted signal circuit is the cause of the failure condition.

This step determines if a shorted 5 Volt Reference circuit is the cause of the failure condition.

This step determines if an open sensor ground circuit between the FPS connector and the circuit splice is the cause of the failure condition.

Step	Action	Value(s)	Yes	No
1	Did you perform the AF Powertrain On-Board Diagnostic (OBD) System Check?	--	Go to Step 2	Go to Alternative Fuels (AF) Powertrain On Board (OBD) System Check
2	Turn the ignition ON leaving the engine OFF. Using a scan tool establish communication with the AF ECU. Locate and observe the Fuel Pressure Sensor data parameter. Does the Fuel Pressure Sensor indicate voltage greater than the specified value?	4.7 volts	Go to Step 4	Go to Step 3
3	The fault is not present. Refer to Diagnostic Aids. Are any DTC's stored that have not been diagnosed?	--	Go to the Diagnostic Trouble Code (DTC) List	Go to Intermittent Conditions
4	Locate and observe the Fuel Temperature Sensor data parameter. Does the Fuel Temperature Sensor indicate voltage greater than the specified value?	4.7 volts	Go to Step 8	Go to Step 5
5	Remove the fuel tank cover. Refer to CNG Fuel Tank Cover Replacement in the Body Rear End section of the C/K Supplement. Disconnect the fuel pressure sensor (FPS) connector. Connect a 1 amp fused jumper between the FPS Signal circuit terminal and a known good ground. If the jumper fuse opens, repair the Signal circuit shorted to battery voltage. Observe the Fuel Pressure Sensor data parameter. Does the Fuel Pressure Sensor indicate voltage LESS than the specified value?	0.25 volts	Go to Step 6	Go to Step 9
6	Remove the jumper. Connect the test leads of the J 39200 DMM between the 5 Volt Reference circuit terminal and a known good ground. Measure the voltage of the 5 Volt Reference circuit. Is the voltage GREATER than the specified value?	5.2 volts	Go to Step 10	Go to Step 7
7	Connect the J 35616-200 Un-powered Test Lamp between the Sensor Ground circuit terminal and BATTERY POSITIVE. Is the test lamp illuminated?	--	Go to Step 12	Go to Step 11
8	Inspect the Sensor Ground circuit for an open or high resistance condition between the AF ECU connector terminal and the circuit splice. Inspect the AF ECU connector and any in-line connectors (if applicable) for proper terminal contact. Repair wiring or terminals as necessary. Was a repair necessary?	--	Go to Step 15	Go to Step 14
9	Inspect the FPS Signal circuit for an open or high resistance condition between the AF ECU connector terminal and the circuit splice. Inspect the AF ECU connector and any in-line connectors (if applicable) for proper terminal contact. Inspect for a shorted condition between the FPS 5 Volt Reference circuit and the FPS Signal circuit. Repair wiring or terminals as necessary. Was a repair necessary?	--	Go to Step 15	Go to Step 14
10	Inspect the FPS 5 Volt Reference circuit for a short to voltage. The FPS 5 Volt Reference circuit is NOT shared with any other 5 Volt Reference component on the vehicle. Repair wiring as necessary. Was a repair necessary?	--	Go to Step 15	Go to Step 14
11	Repair the open or high resistance condition of the Sensor Ground circuit between the FPS connector terminal and the circuit splice. Is the repair complete?	--	Go to Step 15	--
12	Inspect the FPS connector for proper terminal contact. Repair terminal contact as necessary. Was a repair necessary?	--	Go to Step 15	Go to Step 13
13	Replace the fuel pressure sensor. Refer to Fuel Pressure Sensor Replacement . Is the replacement complete?	--	Go to Step 15	--
14	Replace the AF ECU. Refer to Engine Control Unit Replacement . Program (flash) the replacement control module with the correct vehicle software and calibration. Is the replacement complete?	--	Go to Step 15	--
15	Using a scan tool clear the DTC information from BOTH Control modules. Operate the vehicle under the Conditions for Running the DTC. Using the scan tool parameter DTC STATUS, ensure that this DTC runs. Did this DTC RUN and PASS?	--	System OK	Go to Step 2