Perplexing Battery Issue

simaster

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I was out of town and I apparently left my driving lights on. Unfortunately by the time we found out, the battery was dead. I replaced the battery when I got home. I forgot to let the truck sit for 6+ hours while the it 'relearned' everything. I started it right up. I drove it for 20 minutes and when I got home it would not shut off. The electrical would shut down, but the engine kept running. I had never encountered this. I wound up disconnecting the battery (fail) and I ultimately had to pull a fuse to get the engine to stop.

I let the truck sit overnight with a reconnected battery.

This morning the truck would not start. Battery completely drained.

I can confirm there was nothing 'on' to drain the battery overnight.
I checked fuses. No issue.

Could it be I bought a bad battery? Probability is greater than zero, but pretty close to zero. I am using an Optima Yellow top

Not sure what to do next.

I could put a new battery in it and try this all over again.
I could have it towed to a dealer...

Any thoughts on this? I'm at a loss here...
 

W0n70n

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That reads like a short or a failing key barrel to keep the motor on after the key had been turned off. What year is the truck? I'm assuming it's a gen 1 but I can't tell. Definitely recommend saying hi in the New Member Forum (don't forget to post pictures of the Prius). I defer to @FordTechOne on this one though.
 

FordTechOne

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Do you have any aftermarket components tied into the BCM or any factory harness? If so, start there. The most common cause of the engine not shutting down when pressing the Start/stop button or turning the ignition cylinder is aftermarket devices/wiring backfeeding voltage into the hot in start/run circuits. If there are no aftermarket wires/devices tied in, the BCM may have been damaged by the high amperage draw slowly draining the battery. At that point you'd want to check for DTCs with IDS or ForScan.
 
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simaster

simaster

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Do you have any aftermarket components tied into the BCM or any factory harness? If so, start there. The most common cause of the engine not shutting down when pressing the Start/stop button or turning the ignition cylinder is aftermarket devices/wiring backfeeding voltage into the hot in start/run circuits. If there are no aftermarket wires/devices tied in, the BCM may have been damaged by the high amperage draw slowly draining the battery. At that point you'd want to check for DTCs with IDS or ForScan.
I have AMP Research Power steps, an Dyno-Comp tuning package (includes AFE Power Momentum GT Air intake, high-flow air filter and tune).
 
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simaster

simaster

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So today, I replaced the battery and drove it the recommended 10 miles. When I got home it wouldn't shut off (again). I decided not to muck around anymore and just kept driving to the dealer. It was end of day and I wasn't expecting much from them. The service guy was able to shut it down. He said if you toyed with the button a bit it would eventually shut off. I was given the choice to take it or leave it. I left it.

He mentioned it could be the aftermarket tune that is creating problems. I have a hard time with that one. I have replaced a battery in it before. They could flash the tune back to factory and rule it out. But I'll have to get it re-tuned after...

He also mentioned the computer (I forget the acronym) could be damaged and need to be replaced.

A tech will have to look at it tomorrow.

Will keep you guys in the loop.
Thank you for the input @FordTechOne and @W0n70n
 
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simaster

simaster

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Update:
Day two at the dealer. Service rep texted me -
- Flashed PCM back to stock, but still has the issue of not turning off.
- Has an Aux Trans Pump code showing up. Trans tech trying to troubleshoot that to see if that is part of the problem.
- if not, next step would be to assess whether it needs a new Powertrain Control Module and Body Control Module Replaced.
 

FordTechOne

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Update:
Day two at the dealer. Service rep texted me -
- Flashed PCM back to stock, but still has the issue of not turning off.
- Has an Aux Trans Pump code showing up. Trans tech trying to troubleshoot that to see if that is part of the problem.
- if not, next step would be to assess whether it needs a new Powertrain Control Module and Body Control Module Replaced.
Any chance your AMP running board module is near the PCM or BCM? I have seen them take out a PCM on a Super Duty before, they release a ton of Electromagnetic Interference.
 
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simaster

simaster

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So i finally had some progress with the Ford dealer diagnosing after a week:
- "Engineering" theorized there was something feeding voltage to the start/run circuit in the battery junction box. That led to more troubleshooting...
- They found the circuit that was feeding voltage. It's the circuit that runs the transmission relay, cruise control module, transfer case control module, and rear window defrost. They had to find what was feeding the voltage.
- Got the news today "found wiring harness behind firewall from distribution box melted/overheated. Suspect water intrusion into box. Will need box and harness replaced." See pic

$5,195.85


Merry Christmas!
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