No crank bcm testing

Good quality scan tool, ECM/BCM breakout box for individual circuit testing. So no this is not something for a novice to be messing with. One wrong move and you could wipe the programming.

Yeah, I'm not a novice. I have a good quality scan tool and scope. There's a way of testing the crank circuit. I just don't have access to the info. Thx anyway

Check the ignition switch first for signal voltage. Scan tool should show the crank signals in the live data. Or using the scope you can check the signals in and out of the ECM and the BCM by just connect the tap into the correct wiring port.

Yes. I checked the switch, I have 12v power on pink wire and ko power on the pink yellow wire. That's as far as I got today. I'm thinking it's either bcm or signal wire to relay. I can bypass relay and start it. So that part is good. It's somewhere between ign switch to relay.

During crank the headlights go dim, dash lights are on

Did you test the relay? You may want to run a load test on the battery just to make sure you have enough energy in it. If it drops below 9.6 it may not have enough to keep everything hot during crank.

Relay is good. No signal power at relay. And again it starts if I bypass relay. So the battery wouldn't be the issue. And I tested it anyway.

Did you make sure the security system isn’t active?

Yes I check security. Light goes out when key is turn3d on. And had no codes

Okay then see what live is telling you in the crank position, if it shows signals then you have wiring issues to the relay, if not then you could have either the ECM/BCM corrupted programming or wiring issues to those modules.

Good morning. I plugged in scanner. It shows a crank signal on the pad. But I do have a code for high circuit in oil pressure. P0523. The pid shows 129.3 is. Shows the same in koeo or koeo. Could this cause a no crank situation? I'm going to put a new sensor in and try that next.