Question about Pontiac Cars & Trucks
It may run fine but it's in fail safe mode
DTCs P0351 through P0354 Ignition Coil Primary/Secondary Feedback Circuit diagnostic monitors the primary circuitry of individual ignition coils for the successful completion of an ignition event. The ignition trigger signal and ignition fail-safe input signal provide crucial information in the control of ignition system timing and the activation of the fail-safe function. Based on the initial timing angle, calculated from the crankshaft and the camshaft position signals, the powertrain control module (PCM) calculates the ignition trigger signal. The ignition trigger signal is then sent to the ignition control circuitry located in each ignition coil. The ignition control circuitry initiates the ignition dwell period by commanding the power transistor ON. When the PCM determines the proper time to provide spark, the PCM turns OFF the ignition trigger signal. In response to the PCM signal, the ignition coil control circuitry turns OFF the power transistor, producing a high voltage discharge from the secondary coil windings. After the spark has occurred, the control circuitry sends an ignition fail-safe input signal back to the PCM, confirming that an ignition event has taken place. If the ignition fail-safe input signal is not received by the PCM, a cylinder specific DTC will set.
Anytime the fail-safe input signal is lost, engine operation will enter the fail-safe function. If engine load exceeds certain parameters during the fail-safe function, Fuel Cut-off mode is activated and fuel injector operation is ceased. The suspension of fuel injection in the Fuel Cut-off mode protects the catalytic converter from damage. Damage can occur when excess unburned fuel reaches the converter and causes the catalyst to overheat.
• Check for the following conditions:
- An interruption of the ground circuit or voltage supply to the ignition coil will prevent a proper ignition event from taking place. A DTC P0351 through P0354 will set if there is a fault in any of the ignition coil circuits.
- If DTCs P0352, P0353, and P0354 are present, the fault is located in the shared electrical circuits or shared components of the ignition coils.
- Inspect the ignition coil grounds at G 105 for a clean and tight connection.
- The scan tool data parameters for Misfire Current Cylinder # are frozen at the time the MIL illuminates when the DTC sets.
- If no engine misfire is felt when the DTC sets, inspect for a fault in the Ignition Fail-Safe Input circuit.
- Inspect the noise filter for an internal short or low resistance. The ignition coil may not receive adequate voltage during high load conditions if the noise filter is faulty. A good noise filter will indicate infinite resistance (OL) with a DMM after the capacitor inside the filter is charged up.
- Unless the ignition key is cycled or the DTCs are cleared, the PCM waits to receive ignition fail-safe signals before providing fuel injector operation.
• An intermittent malfunction may be caused by a fault in the ignition coil electrical circuit. Inspect the wiring harness and the components for an intermittent condition. Refer to Intermittent Conditions .
• Repair any electrical circuit faults that were found. Refer to Wiring Repairs .
• The information included in the Freeze Frame data can be useful in determining the vehicle operating conditions when the DTC first set.
Posted on Dec 22, 2017
all refer to the coils A,B,C,D===causes wiring, ignition coils ECM
for all to go out at once , I suspect a harness connection ot a failed ECM
substitute the ECM with a known good one to prove it before buying an ECM
Posted on Dec 20, 2017
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