Diagnostic Aids

WARNING: This page is about a different car, the 2004 GMC Sierra, 2004 GMC Cab & Chassis Sierra, 2004 Chevrolet Silverado, and 2004 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

If you have to prime the fuel system, inspect for the following conditions:
- A restricted fuel supply line
- A fuel supply line air leak-Refer to Fuel System Diagnosis
If the condition is still intermittent, refer to Intermittent Conditions .

DTC P1094

Step	Action	Values	Yes	No
Schematic Reference: Engine Controls Schematics
1	Did you perform the Diagnostic System Check - Engine Controls?	-	Go to Step 2	Go to Diagnostic System Check - Engine Controls
2	Is DTC P1093 also set?	-	Go to DTC P1093	Go to Step 3
3	Inspect for fuel contamination. Refer to Contaminants-in-Fuel Diagnosis . Did you find and correct the condition?	-	Go to Step 10	Go to Step 4
4	Attempt to start the engine. Does the engine start and continue to run?	-	Go to Step 5	Go to Engine Cranks but Does Not Run
5	Is the customer concern also a surging idle?	-	Go to Fuel Pressure Regulator Diagnosis	Go to Step 6
6	Start and idle the engine. Observe the fuel rail pressure (FRP) regulator fuel flow with a scan tool. Does the FRP regulator fuel flow measure more than the specified value?	12 000 mm³	Go to Step 7	Go to Diagnostic Aids
7	Test the fuel pressure regulator solenoid control circuit between the engine control module (ECM) and the fuel pressure regulator for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?	-	Go to Step 10	Go to Step 8
8	Test for an intermittent or poor connection at the ECM. Refer to Testing for Intermittent Conditions and Poor Connections andConnector Repairs in Wiring Systems. Did you find and correct the condition?	-	Go to Step 10	Go to Step 9
9	Replace the ECM. Refer to Engine Control Module (ECM) Replacement . Did you complete the replacement?	-	Go to Step 10	-
10	Clear the DTCs with a scan tool. Turn OFF the ignition for 30 seconds. Start the engine. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records. Did the DTC fail this ignition?	-	Go to Step 2	Go to Step 11
11	Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed?	-	Go to Diagnostic Trouble Code (DTC) List	System OK