P050B
P050B-COLD START IGNITION TIMING PERFORMANCE
Special Tools:
For a complete wiring diagram, refer to the Wiring Information.
- When Monitored:
During a cold start condition, with the difference between the AAT and ECT at startup below 10°C, and the engine running at idle.
- Set Condition:
The Powertrain Control Module (PCM) detects that engine speed is 50 RPM or more (depending on vehicle specifications) below target idle speed for more than three seconds, and the average spark advance is above the failure threshold for more than the specified limit. Two trip fault. Three good trips to turn off the MIL.
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. PCM Pre-Diagnostic Troubleshooting Procedure.
Diagnostic Test
1. ACTIVE DTC
NOTE: Low battery voltage can cause excessive current draw in very hot and very cold ambient temperatures. Look closely at the temperatures at which this DTC set and make sure the battery can pass a load test before continuing.
NOTE: Diagnose and repair any other DTCs set in the PCM before proceeding with this test.
1. Turn the ignition on.
2. With the scan tool, select View DTCs and review the DTC environmental information.
Is the DTC Active at this time?
Yes
- Go To 2
No
- The DTC is not active at this time. Perform the INTERMITTENT CONDITION diagnostic procedure. PCM Intermittent Condition Test.
2. THROTTLE PLATE INSPECTION
1. Turn the ignition off.
2. Remove the air cleaner assembly.
3. Check for any signs of a foreign material (ice, dirt, or excessive carbon build up) on the throttle plate or in the bore causing the throttle plate to stick.
Were any problems found?
Yes
- Remove the debris if possible or replace the Throttle Body. Disconnect the battery when replacing the Throttle Body. After installation is complete, use a scan tool and perform the ETC RELEARN function.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
No
- Go To 3
3. DIRTY AIR FILTER
1. Remove and inspect the air filter.
Were any problems found?
Yes
- Replace the air filter.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
No
- Go To 4
4. CONTAMINATED FUEL
1. Inspect the fuel for contamination. (dirt, water, or other foreign material)
Were any problems found?
Yes
- Drain the fuel from the fuel tank into an approved gas holding tank and add clean fuel. Procedures.
No
- Go To 5
5. CHECK FOR EXCESSIVE RESISTANCE IN THE (K124) ETC MOTOR (+) CIRCUIT
1. Turn the ignition off.
2. Disconnect the PCM C2 harness connector.
CAUTION:
Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install the GPEC Diagnostic Adaptor to perform the diagnosis.
3. Connect the (10436) in line with the PCM C2 harness connector.
4. Using a voltmeter, perform a voltage drop test by back probing the (K124) ETC Motor (+) circuit at the Throttle Body harness connector and by probing the GPEC Adaptor. Make sure the voltmeter leads are connected so that positive polarity is displayed on the voltmeter.
WARNING:
When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts or fan. Do not wear loose clothing. Failure to follow these instructions may result in possible serious or fatal injury.
5. Start the engine.
Is the voltage below 0.2 volts?
Yes
- Go To 6
No
- Repair the (K124) ETC Motor (+) for excessive resistance.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
6. CHECK FOR EXCESSIVE RESISTANCE IN THE (K126) ETC MOTOR (-) CIRCUIT
1. Turn the ignition off.
2. Using a voltmeter, perform a voltage drop test by back probing the (K126) ETC Motor (-) circuit at the Throttle Body harness connector and by probing the GPEC Adaptor. Make sure the voltmeter leads are connected so that positive polarity is displayed on the voltmeter.
WARNING:
When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts or fan. Do not wear loose clothing. Failure to follow these instructions may result in possible serious or fatal injury.
3. Start the engine.
Is the voltage below 0.2 volts?
Yes
- Go To 7
No
- Repair the (K126) ETC Motor (-) for excessive resistance.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
7. THROTTLE BODY
1. Turn the ignition off.
2. Measure the resistance of the ETC Motor by probing the appropriate terminals of the PCM C2 harness connector for the (K124) ETC Motor (+) circuit and the (K126) ETC Motor (-) circuit.
Is the resistance between 2.5 and 25 Ohms at closed throttle?
Yes
- Go To 8
No
- Replace the Throttle Body. Disconnect the battery when replacing the Throttle Body. After installation is complete, use a scan tool and perform the ETC RELEARN function.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
8. POWERTRAIN CONTROL MODULE (PCM)
1. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Throttle Body and the Powertrain Control Module (PCM).
2. Look for any chafed, pierced, pinched, or partially broken wires.
3. Look for broken, bent, pushed out or corroded terminals.
4. Perform any Technical Service Bulletins that may apply.
Were any problems found?
Yes
- Repair as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
No
- Replace and program the Powertrain Control Module (PCM). Powertrain Control Module - Removal.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.