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2012 Acadia in my bay now. Worked on by owner and Seen other techs for crank no start and crank stall conditions. I know it has recently got new throttle body, MAF, CKP sensor and HPFP. Not sure what else has been done recently. Initially had crank no start and I found low pressure fuel sensor dropped from 72 psi to 52 psi when key on within 5 seconds. Fuel sending unit Waveform terrible only made out 4-5 of the pump magnets with increased amperage drowning out others. Replaced fuel sending unit now cranks stalls within seconds at times. Checked cam crank timing. Intake bank 1&2 perfectly aligned. Crank waveform not consistent on scope. Verified continuity from ECM to CKP sensor. I’m new to scopes but leaning towards bad reluctor on crank. Initial CKP was a spike every 10th/second. (During crank no start) Then decent CKP with variable signals resulting in crank stall conditions. Sorry no video but here are some pics of scope.
Setting any codes?
I think the 1 second time base on the scope is too much time to be able to judge the CKP signal.
Will it run with the CKP disconnected?
These were in memory when I first got it:
P0108 MAP sensor high voltage.
P1682 ignition switch circuit 2 test failed since dtc cleared
P069E FPCM requested MIL
U0109 lost comm w FPCM since DTC cleared
P00C6 fuel rail press low during crank
P00C8 fuel press regulator solenoid positive voltage control circuit
It will not crank with CPK unplugged. Battery is weak
Those Codes no longer there after disconnecting battery and replacing fuel sending unit in tank.
It currently has the following:
P0335 CPK sensor circuit (it’s unplugged now)
P062F control module long term memory performance
This is a mess. I have a short to ground somewhere I have to find. Continuity from battery pos to ground, only when voltage is applied. I’m convinced there is a relay or module somewhere causing this. CAN and GM LAN networks appear good to me on scope. I’ve found multiple aftermarket wires and terminal ends without wires throughout vehicle. Maybe alarm, or sound system previously installed. Thinking this short was interfering the CKP signal causing the crank no start or stall issues. Boy I wish this had landed in someone else’s bay!
Well, here I am again. Don't know what I was thinking when I mentioned the continuity when battery applied. I get stupid sometimes. Duh of course! SO I am back on this vehicle. I found 120ohms between pins 6/14. The ABS module had a connector securing pin broken. Using zip tie to maintain connection and now keeping 60 ohms on pin 6/14. I do notice a constant high pitch humming from TCM even with key out of ignition. This occurs every time battery is connected and does not stop (have to keep 2amp charger to prevent battery drain. Now I continue to get crank no start or crank stall (within 2-3 seconds). Looking at scan tool I do not see any security codes. Key is recognized. No security light illuminated on dash.
I have tried clearing codes (I have previous ones saved on Zeus). Now getting airbag code B1019 (system config error incorrect component installed symptom 3A). Also have the following OBDII permanent codes: P0420 (cat efficiency below threshold bank 1), P0430 (cat efficiency below threshold band 2), P0300 (random misfire), P0090 (fuel press. regulator A control circuit/open), P2535 (ignition switch on/start position circuit high), U0100 (lost comm w ECM/PCM), P018D (Fuel press sensor B circuit high, P018C Fuel press sensor circuit B low.
I have watched many SD videos and I am on a serious struggle bus!! I welcome any input to the situation that anyone may have.
Also noteworthy is that this must have been a public service vehicle at one point. I have found numerous aftermarket devices, sirens, etc that have I have removed to try and get back to original OE condition...
I’m going to have to cut my losses on this one. I’m seriously leaning towards ECM, but not confident enough to make that call. Decided to look at cam crank again with lab scope again since I had an anomaly the first time with crank waveform. Had something really strange happen. At one point crank had no voltage at all even while cranking. Few minutes later cooling fan kicks on randomly. Then notice bank 2 intake signal wire has 5v and key was out of ignition on dash (it doesn’t have push button).
faulty ECM is my only guess at this point. My issue is I have so much difficulty reproducing the problems to convince myself to replace the part. Time to take an L on it.
It sounds like you've been pretty thorough. With the abs module connector fully seated, could you communicate with all the module on the HS network?
It is very common for that connector to not seat well, as you mentioned and noticed with the 120 ohm network resistance.
That condition alone will create a no start condition on that vehicle.
Seems like a frustrating problem, don't let it weigh on you too much.
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