starting and OBD PCM problem?
12-04-2018, 11:01 PM
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starting and OBD PCM problem? hello all.. looking for some guidance. 2000 TA WS6 M6 - was having issues due to low battery. jumped it a few times with a battery pack and had a battery charger on it in attempt to bring it back to life. it would start ok but sometimes it would just instantly stall out and shut off while at idle. it would typically restart, but that seemed weird.. so i gave in and got a new battery. all seemed ok for a while.. car sat for 6 weeks or so and i went to start it.. battery was strong and it cranked well.. just wouldnt start. i have a fuel pressure gauge and that is reading 52-55. i tried hooking up my OBD scanners and they power up but cant get any communication. i read some generic OBD page that explains pin 2 (data) should have some voltage.. 3.5-5V. i see about 0.4. I'm wondering if it may be ECM related. it looks like i have good ground on pins 4 and 5. Can someone confirm what DC voltage I might see on pin 2 with key on engine off? any other ideas?? TIA...
12-05-2018, 08:03 AM
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There isn't DC voltage on pin 2. Pin 2 is a PWM (Pulse Width Modulation) data signal with voltage varying between 0V and 5V in the pulses. You can't measure it with a DC voltmeter because the average voltage will vary depending on what data is moving. The only DC pins in the connector are ground (pins 4 and 5) and battery power (pin 16... nominally 12V).
12-05-2018, 08:10 AM
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understood on the pwm, though i read somewhere that it would still appear as some DC voltage on a meter. not sure how to troubleshoot the obd comm problem.. i should be able to communicate key on engine off, right?