Electrical issue - speedometer dies, radio shuts off, ABS light kicks on

[Hattrick382]

Quick background on the car:
2015 - upgraded intake, charge pipe, intercooler, BOV. I bought the car 4 months ago with mods already installed. Previous owner had a Dizzy tune although I'm pretty sure he took it off (i bought from a dealer so i dont have PO's direct contact to ask the questions). I've been running 87 octane with no issues or detonation.

I need some help troubleshooting. Here goes:

2 days ago I was cruising on the freeway when my radio shut off. After a couple seconds it turned itself back on. I thought I was crazy at first. Then it did it again and again. I figured sync was just glitching.

Next day I'm driving and it does it again. Now I'm getting irritated. Only right as I get mad at the radio the speedometer dies 10 mph and the ABS, brake, and traction control lights all come on. This happens for no more than a second and then things are back to normal. At first it only did it a few times and would stop for a while. Now it's happening consistently. I've also found at idle you can see the lights flickering sometimes (I only notice it when it's dark outside).

I've found that if I keep the RPM's under 2k the problem mostly stays away. When i rev it up that's when the problem happens very consistently.

I read on a previous post about a similar issue being a bad alternator. So I hooked up the volt meter and I thought I had the problem identified. The voltage would sit at 13.05 and not move at all regardless of revving the engine. All the sudden it would kick up to 14+ bolts randomly then just as quick back to 13.05. I'm used to seeing alternators voltage fluctuate with the engine speed so I thought I had her licked.
Bought a motorcraft alternator and installed it tonight. Took it for a test drive and the exact same problem came back after a couple mins of driving.

Checked voltage and a similar thing is happening. 12.97v sitting there. I revved it up and the voltage stayed the same. It would randomly kick up to 14+ and then settle right back to 12.97 where it stayed for the most part.

I really thought the alternator was the problem considering when I'm revving above 2k rpm the problem consistently happens. Under 2k rpm it almost never happens.

Thought?

 

[SteveS]

Flaky electronic behavior often signals a weak battery on its way out. When you replace the battery be sure to reset the battery control module or you can continue to have problems.

 

[Hattrick382]

Strangely enough this morning after doing the fault on initial start up it did not do it again the rest of the way into work. I did hook up my OBDII scanner and monitored voltage at both the ECU and OBD port while driving. Both voltages stayed above 14.1 the entire way in. I was already leaning toward both of your suggestions, battery failing. It's a duralast battery that looks new-ish but i can't find a date on it. I'll swing by O'Reilly's and get it tested then go from there.

 

[SteveS]

I'd still do the battery control module reset. It's easy, cheap, and fast. Follow this video (except substitute pressing the start button but not starting engine for turning the key but not starting the engine)

View: https://www.youtube.com/watch?v=33dCWXR6uFs

 

[Hattrick382]

Update:

Issue came back after some more driving. It seems to happen more when i have the RPM's over 2k. If i keep it under 2k it doesnt seem to happen much if at all.

I swung by O'Reilly's and had the battery tested. It tested good (no surprise). The battery was manufactured 05/23 so it's only 1.5 years old. Car starts fine with no issues even on cold mornings.

I did the battery control module reset. That actually took care of the problem for a couple days. Then the fault randomly came back.

I pulled the battery completely out to check the manufacturer date which was on the back side. After re-installing and performing the battery module reset, the problem has stayed away for 2 days. I have my scanner hooked up all the time while I'm driving now so the next time it does the fault I can see the voltage at the ECU and at the OBD-II port.

Still not completely sold on it being the battery. I'll keep monitoring for now.

 

[SteveS]

If the battery is absolved of blame the next thing would be to look for something that would look to the ECU/BCM like a weak battery, i.e. something making the current supplied to them drop.

 

[Hattrick382]

Alternator is a brand new motorcraft so that shouldn't be a problem anymore.

 

[SteveS]

I'm talking wiring/connections.

 

[Intuit]

All the sudden it would kick up to 14+ bolts randomly then just as quick back to 13.05. I'm used to seeing alternators voltage fluctuate with the engine speed so I thought I had her licked.
Bought a motorcraft alternator and installed it tonight. Took it for a test drive and the exact same problem came back after a couple mins of driving.

Checked voltage and a similar thing is happening. 12.97v sitting there. I revved it up and the voltage stayed the same. It would randomly kick up to 14+ and then settle right back to 12.97 where it stayed for the most part.

I really thought the alternator was the problem considering when I'm revving above 2k rpm the problem consistently happens. Under 2k rpm it almost never happens.

https://www.amazon.com/gp/product/B085LKLCYX/
The BMS voltage regulation system is fairly advanced so it won't behave like the old setups. I've had one of the above volt meters in my front outlet for years.
It's possible that it may be assessing your battery.
What do you mean by "lights" flickering?

Two maybe if possibly probably relevant experiences to share.

On a prior vehicle with the relatively "dumb" power regulation system, a dilapidated engine ground caused high voltage drop between the engine and battery. The voltage regulator circuit in the alternator relying on grounding, had a bad reference. In this case it caused excessive output. I was able to measure the voltage drop and saw it get worse with additional power, engine RPM. Web search "voltage drop test". IIRC a loss of 6% or greater is considered excessive. I didn't fix the original engine ground but instead, added additional between engine, frame, battery.

Second experience but on this vehicle, my driver side DRL gradually began flickering, more often and worse. Did this for quite some time but paid it little mind. At some point in the future, my intermittent wiper function began to behave oddly in conjunction with turn signal flashes. The cause of all of it, failing load resistor circuit, built into the aftermarket LED headlights began dumping excess current off to ground. The DRL shared a ground with the headlamp, and the ground ran back to the BCM which controls the wipers and turn signals. (since our vehicles don't care about a burned out headlight, such circuits are unnecessary anyway)