Diagnosing an intermittent problem can be challenging and frustrating. If you deduced that the problem could be electrical, use the power of your scope to test four signals and compare the relationships of each circuit. Notice that the examples below are selected screens from recorded data. The four channel record function will save time when searching for that elusive glitch.
Helpful hint: Set the trigger on a crank reference signal so that the scope will stop when the engine stops. There will be up to 50 screens saved at this time. Press the Utility function key and review and/or save the recording into a file.
Figures 1 and 2 were captured with Omitec's ECVu. The left graphic shows normal operation and the right graphic captured the problem when the engine stalled. The SPOUT signal failed.
Figures 3 and 4 show a normal running condition on the left and the beginning of the stalling condition on the right. The trigger was set to monitor supply voltage to the vehicle's PCM. The engine stalled when the supply voltage dropped.
Figure 1
Figure 2
Figure 3
Figure 4
