CODE 41, CAM SENSOR CIRCUIT Quick reference: See Fig. 45 for Code 41 flow chart. " See Fig. 44 for Code 41 supplemental wiring. " All Updated Information All the Code 41 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 All outdated information has been discarded.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 91-6E-14 " Oldsmobile 91-T-45 " Pontiac 91-6-18 " Circuit Description The 3800 engine uses the simultaneous mode of fuel injection during start-up. As the engine speed attains the 400 RPM level and a cam signal has been received by the ECM from C3I module, the fuel injection switches modes to sequential injection. This is accomplished by use of a cam interrupter magnet and a cam sensor "Hall Effect" switch. The cam sensor sends a signal (sync-pulse) to the ignition module when cylinder #1 is 25 after top dead center on the compression stroke. This signal is used to start sequential fuel injection with the proper cylinder. If cam signal is lost to the ECM, the fuel delivery will switch back to the simultaneous mode of injection. THE ENGINE WILL CONTINUE TO RUN. IT WILL RESTART AFTER SHUT DOWN. Code 41 is set when the following conditions are met: Engine is running. " Cam sensor signal not received by the ECM in last 2 seconds. " Test Description The numbers below refer to the circled numbers in the diagnostic flow chart. This step verifies proper operation of circuits 633, 644, and 645. See Fig. 44 for circuit identification. 1. Step validates the integrity of Circuit 630 from the ignition module to the ECM. See Fig. 45 for circuit identification. 2. 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. 3. If the voltage reading of terminal "BC5" is constantly varying and connection to terminal "BC5" are good, the ECM is faulty. 4. V The magnet or gear may be damaged, Posted By: PCS agent 6 Flag Post For Monitor Review
Shop: MITCHELL 1
Date: 4/16/2009 11:00:24 AM
The Cam Gear magnet is installed from the back side of gear. The stronger side of magnet is facing towards the waterpump.
Sunday, May 10th, 2009 AT 8:14 AM