Measuring VCC pin8 shows only 0.3V

Testing the v3.3 units purchased recently (#316, #317, #328 & #360) with this: Magnetti Marelli sensor - which is a common sensor used by the likes of Omex and MM themselves. Its resistance was measured at ~620 Ohms.

It turned out that the testbench (not the factory testbench of course, but the testbench built by the customer) with missing GND (EC36pin26) connection ruined the P259 (TPIC6A259) chip in 2 of the ECMs. The P259 chips shorted the supply for the LM1815 (VR-input-processing) trigger chip. Removing the P259 fixed the problem. (There are 10 FETs installed anyway which provide enough outputs, so the P259 outputs usually not used for a 4-cyl anyway). Grounds must be connected (GND and GND5 wires), there has never been an exception to this rule for assembled controllers (unassembled bare boards were shipped with an GND-GND5 arch in 2004, to remind the user of the importance of ground wires: but the arch is cut during assembly), more on MembersPage/PhatBob/UserGuide.

After Emil's suggestion I took a VR sensor with a 500 Ohm impedence and wired it to the EC36 plug on my bench. Testing on a known working unit (316)I set the primary trigger type to coil and put the sensor on a mains adaptor, it gave a value constant reading of around 1500rpm. One of the suspect units was then tested with the same settings and there was no reading (0000rpm)

We should examine the VR waveform. This depends on the toothwheel (not the sensor: 800 Ohm should not be a problem by itself). If the amplitude at the missing tooth is way too high (max difference between amplitude of any 2 teeth should be < 15%), it is possible that one ECM triggers properly and another not. Obviously, either ECM must trigger OK on a proper-waveform VR signal. Watch wheel-error, since that might be a good indication of this. Do you have a picture of the toothwheel ?

The logs above (for 317 and 360) show B6=0000 (watch the 2nd B6=.... not the first) which means there is absolutely no trigger detected during or before the capture-period (not just lost teeth because of tooth-amplitude).

Pictures of tooth wheel



This wheel works with Omex systems and two of the v3.3s