CODE E041, CAM SENSOR CIRCUIT ("E" BODIES; 3.8L)
Quick reference
- see scheme 102for Code E041 flow chart.
- (Scheme 314)for Code E041 supplemental wiring.
All the Code E041 information here (including the flow chart) has been updated as per the General Motors Technical Service Bulletins (TSBs) listed below. All outdated information has been discarded.
- Buick 90-8-22
- Oldsmobile 91-T-45
During cranking, the ignition module monitors the dual crank sensor sync signal. The sync signal is used to determine the correct cylinder pair to spark first.
After the sync signal has been processed by the ignition module, it sends a fuel control reference pulse to the ECM. When the ECM receives this pulse it will command all six injectors to open for one priming shot of fuel in all cylinders.
After the priming, the injectors are left off for the next six fuel control reference pulses from the ignition module (two crankshaft revolutions). This allows each cylinder a chance to use the fuel from the priming shot.
During this waiting period, a cam pulse will have been received by the ECM. Now the ECM begins to operate the injectors sequentially based on true camshaft position.
However, if the cam signal is not present at start-up, a Code E041 will set and the ECM will start sequential fuel delivery in random pattern with a 1 in 6 chance that fuel delivery is correct.
The numbers below refer to the circled numbers in the diagnostic flow chart.
- This step verifies proper operation of circuits 633, 644, and 645. (Scheme 312)for circuit identification.
- Step validates the integrity of Circuit 630 from the ignition module to the ECM. (Scheme 313)for circuit identification.
- If the camshaft gear magnet is interfacing with the cam sensor the voltage reading will be zero, bumping engine will cause the condition to go away.
- If the voltage reading of terminal "BC5" is constantly varying and connection to terminal "BC5" are good, the ECM is faulty.
An intermittent may be caused by a poor connection, rubbed-through wire insulation, or a wire broken inside the insulation.
Check for the following
- Poor Connection or Damaged Harness: Inspect ECM harness connectors for backed out terminal "BC5", improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wire connection and damaged harness.
- Intermittent Test: If connections and harness check okay, monitor a digital voltmeter connected from ECM terminal "BC5" to ground while moving related connectors and wiring harness. If the failure is induced, the voltage reading will change. This may help to isolate the location of the malfunction.
