dredman1

Does anyone monitor the voltage of their car, or can say the regular voltage reading these cars should be giving while driving?

For about a year now I've had a scangauge hooked up that displays voltage, but earlier this month I started to notice it fluctuating anywhere between 12.5v and 14.1v randomly while driving. I’m not sure if this is a problem or if this is normal for these cars, since I’ve never noticed this fluctuation before. I don’t recall it ever happening as to my recollection it used to be constant at about 14.1v, but I could be wrong – I just never paid much attention to the voltage before.

The fluctuations seem to only happen while driving. With the car parked and idling, the voltage stays fairly constant at between 13.9v to 14.1v.

The battery or charge light on the dashboard does not come on at all when it is fluctuating, hence why I’m wondering if it’s normal for the car.

In trying to isolate the issue, so far I cleaned and secured the battery terminal connections, checked the connections on the alternator itself (they were tight and secured), checked the alternator belt tension (it is taut) and condition (no cracks and still soft). I also installed a new battery for good measure, to make sure that wasn’t the problem, but no change – the voltage is still fluctuating while driving. Also, whether or not the A/C and/or headlights are on or off makes no difference (the fluctuations occur either way), in case that was a question.

Are the alternators/voltage regulators in these cars known to be problematic, or is this normal?

Any feedback is greatly appreciated in trying to troubleshoot this.

CamShaft

You are most likely reading engine ECU voltage with that scangauge. You could be detecting the start of a problem in the wiring to the engine ECU. Ground or power wires could have corrosion somewhere and you are reading the voltage drops when your ECU puts more of a load on the circuit. The only way to tell for sure is to hook up a multimeter off a good known ground and power then monitor both and see if they fluctuate the same. If so, possibly a bad battery/alternator/wiring.

dredman1

Ok. Well the battery isnt the problem. I swapped it for a brand new one and the voltage still fluctuates.

Since the fluctuations only happen while driving, it's kinda difficult to get a multimeter to the battery to get a true reading.

Would a direct reading from the fusebox be a true enough reading?

CamShaft

run some leads and connect to the battery, out the hood and into the cabin. Then monitor from there. You can try the fuse panel, but that may not necessarily rule out that circuit as well.

Jbone

This is almost my exact problem. Did you ever figure out exactly what is causing it?

dredman1

Nope, it's still happening.

I did speak to a US Mitsubishi technician, and he told me that the newer model (2011+) Lancers have an "active regulator" to drop voltage when there was less demand for it (to reduce load on the engine).

He suggested once there was no low battery warning lights, DTC codes, or dimming interior or dashboard lights, it sounds normal (for that active regulator). However, I don't know how true that is, or if for sure that's the case with my car.

He suggested I keep monitoring it, and once I don't get any of the above symptoms I should be fine. I haven't had any of those symptoms, although the voltage is still fluctuating.