Circuit/System Testing

WARNING: This page is about a different car, the 2019 GMC Savana 3500, 2019 GMC Savana 2500, 2019 Chevrolet Express 3500, and 2019 Chevrolet Express 2500. However, it is still accessible from the selected car via links, so may be relevant.

NOTE:

This diagnostic assumes the following:

The battery is completely charged.
The engine cranking speed is acceptable.
There is adequate fuel in the fuel tank.

Crank the engine for up to 15 s.
Verify that DTC P0117, P0118, P0122, P0123, P0201 - P0206, P0222, P0223, P0335, P0336, P0351 - P0356, P0513, P0562, P0563, P0601 - P0604, P0606, P062B, P062F, P0630, P0633, P0685, P0690, P1516, P1631, P1682, P016F3, or P262B is not set.
- If any of the DTCs are set
  Refer to Diagnostic Trouble Code (DTC) List - Vehicle .
- Go to next step: If none of the DTCs are set
Ignition ON.
Verify the security indicator on the instrument cluster illuminates momentarily.
- If the security indicator stays ON or is flashing
  Review the Diagnostic Trouble Code (DTC) List - Vehicle , for Immobilizer system DTCs. Refer to Immobilizer Description and Operation for additional information.
- Go to next step: If the security indicator does not stay ON and is not flashing
Verify the scan tool Engine Speed parameter displays greater than 0 RPM while cranking the engine.
- If 0 RPM
  Refer to DTC P0335 or P0336 .
- Go to next step: If greater than 0 RPM
Ignition OFF, disconnect one of the spark plug wires from one of the spark plugs.
Connect the EL 26792 HEI Spark Tester between the spark plug boot and ground.

NOTE:

Perform the spark test on at least one cylinder of each cylinder bank.
An erratic or weak spark is considered a no spark condition.

Verify that the spark tester sparks while cranking the engine.
- If the spark tester does not spark
  Refer to Electronic Ignition System Diagnosis .
- Go to next step: If the spark tester sparks
Ignition ON, engine OFF.

NOTE:

If the engine is too hot, high fuel pressure readings may result due to hot soak fuel boiling. Allow the engine coolant temperature to cool to less than 60° C (150° F) before attempting to verify fuel pressure.
The Fuel Pump Enable may need to be commanded On a few times in order to obtain the highest possible fuel pressure.
Additional DTCs may set when using the fuel pump output control.

Command the Fuel Pump Enable On several times with a scan tool.
Verify the fuel pressure is between 320 - 580 kPa (46 - 84 PSI) with the fuel pump running.
- If not within the specified range
  Refer to Fuel System Diagnosis .
- Go to next step: If within the specified range

NOTE:

The fuel pressure may vary slightly when the fuel pump stops running. After the fuel pump stops running, the fuel pressure should stabilize and remain constant.

Verify the fuel pressure, after the fuel pump is turned OFF, decreases to 468 - 544 kPa (68 - 79 PSI) and does not decrease more than 34 kPa (5 PSI) in 1 minute.
- If not within the specified range
  Refer to Fuel System Diagnosis .
- Go to next step: If within the specified range
Verify the conditions listed below do not exist:
- A stuck camshaft position actuator solenoid valve. It may be necessary to perform a dynamic test on the valve to verify correct operation. Refer to DTC P0010, P0011, P2088, or P2089 for instructions.
- Air intake duct to the throttle body collapsed
- Air filter or air intake system restricted
- A skewed engine coolant temperature (ECT) sensor. Compare the actual engine coolant temperature to the ECT Sensor parameter
- Fuel contaminated or of a poor quality - Refer to Alcohol/Contaminants-in-Fuel Diagnosis .
- Spark plugs gas or coolant fouled - Refer to Spark Plug Inspection , and Spark Plug Wire Replacement .
- Exhaust system restricted - Refer to Restricted Exhaust .
- An engine mechanical condition, such as worn timing chain and gears, or low compression - Refer to Symptoms - Engine Mechanical .
- If a condition exists
  Repair as necessary.
- Go to next step: If no condition exists
All OK.