PCM turned off too early after turning engine off?

[bj6395]

Just 2 weeks ago my 16 Explorer Limited started doing something wired. Every time I turn my engine off, it seems the vehicle just lost electricity power right away, both dash and Sync system just go dead/black. Sometimes the system immediately regains power and Sync starts booting, sometimes it just stay dead. However I can restart the engine every time without any issue, and driving is normal as well.

Originally I thought it was a glitch of Sync system because I upgraded to Sync 3 thanks to detailed info I got from this forum. However I then realise this issue is consistent and the vehicle doesn't remember history from previous drive, for example my "Fuel History" is empty every time I start the vehicle.

Finally check engine light went on last Friday and I got codes P068A, P06B8 and U0422. I cleared it and care still runs normally. Today the light just came back on again with codes P06B8 and U0422.

My battery is less than 1 years old, voltage is about 14.4/12.4 with/without engine running. So I am guessing it is not power source but some bad relay maybe? It seems P06B8 might related PCM or BCM turned off too early?

Does anyone has experience with this type of issue? Any help is much appreciated!

 

[peterk9]

You may have already looked up the codes but for others, here are the causes.

P06B8 Internal Control Module Non-Volatile Random Access Memory (NVRAM) Error

How to easily diagnose, repair, and info on causes of a P06B8 trouble code that indicates a detected failure of the NVRAM.

www.obd-codes.com

P068A ECM/PCM Power Relay De-Energized Performance - Too Early this is the one that indicates the PCM turned off too early.

U0422: Code Meaning, Causes, Symptoms, & Tech Notes

How to repair U0422 code Invalid Data Received From Body Control Module

www.engine-codes.com

I'm not sure of the exact PCM operation but there are 4 fuse/relay related listings in the Manual and all are in the engine bay fuse box.

Peter

 

[bj6395]

Thanks Peter for your help. Here is my update.

Since I don't drive much in this pandemic I waited long enough to verify I got this fixed. My issue was caused by corroded positive connector at battery.

Last year I found the original OEM battery had leak at positive connector. More than half of the connector was completely corroded and cannot be securely attached to new battery. So the mechanic fixed that by using a cheap genetic connector.

This time although there were error codes but I just felt the issue was more like power loss instead of control problem. So I switched the engine start relay in fuse box but it didn't fix the issue. I then disconnected positive connector and cleaned wires/connector and reattached it. It wasn't much corrosion I found on the "new" connector but the issue hasn't been back since.

 

[peterk9]

Glad to hear it is fixed. You are not the only one to have experienced that corrosion issue. Corroded Battery Terminal / Cable

Peter

 

[bj6395]

Glad to hear it is fixed. You are not the only one to have experienced that corrosion issue. Corroded Battery Terminal / Cable

Peter

Oh I never noticed that discussion before. Anyway I definitely have a "normal" Explorer because I pretty much have all typical issues, like hood bubble and exhaust odour, plus a few odd ones. But this forum definitely helps me a lot. Thanks again Peter!

 

[peterk9]

There is also an SSM on that issue. See this ost; List of Useful Threads - 2011 + Explorer TSB's & SSM's

Peter