ALT 1 lights comes on with no underlying altenator failure

We are having a problem with our ALT 1 - the light comes on and the analog gauge shows zero amps from Alt 1, but the main bus voltage per the MFD is strong (28+ volts) and there is no evidence of an underlying issue. Any ideas as to what could be wrong? My mechanic thought to change the “logic module”, but that was changed just a few months ago. Thoughts? Thanks

Same thing happened to mine. Multiple diagnosing steps over six months. It turned out to be a specific pin in the Cannon plug going into the MCU. Between Jim Barker and the able folks at my SC (Wisconsin Aviation-RYV) the exact pin was identified on the wiring diagram and subsequently visually verified to be defective. Mine has the MCU 130. The plug was replaced. No problems since.

The same problem has occurred with my 2003 SR-22 for the past 4 years and have ignored it and my malfunctioning amp meter. As long as the alternator puts out 28+ volts at flying rpm, the alternator is working and not an airworthiness issue.

Our number one Alt light comes every 20 min or so.

.Voltage is at 27.7 volts …light comes on and voltage still at 27.7 but no charging amp… then after some time starts charging at 25 amps light is out…then 25 min later or 1 hour latter it repeats…

they have changed many modules and a New Alt…

any Ideas? during trouble shooting the burnt up the wires going to the #2 Alt module and harness

maybe the current sensor, or so that what someone else told me.

maybe jim or roger will chime in

Is this what you were seeing? Volts good and oscilation showing in AMP (toggled to Alt 1 pos) showing little or negative charge or discharge and Alt 1 light on? Alt 1_001.mp4 (782 KB)

Hello, Yes that is exactly what we are getting…27.7 volts at all times

with or without Alt #1 light on or off

thanks how do we fix?? 641 919-8188 wally

exact same problem i have took out the current sensor and cleaned terminals did see a time difference in intervals just received a new current sensor hope to install on friday and try will let now if works wes

I replaced both the current sensor and logic module. Perhaps should have changed one or the other first to see if it corrected. In the end, a few dollars more, but the problem resolved. It’s less frustrating than going to Service Center only to find out a week or two later that the same problem is occurring and then having to go back again.

received a new current sensor from Jim barker at aviation resources 715-822-5787 and installed it yesterday and test flighted and no more alt 1 light, easy to replace just dont forget to seal panel cover to keep out moisture when done … thanks to Jim for his help and prompt shipment thanks Jim and blue skies