My ST4000+ Autopilot Control is also giving me "Low Battery" on the Head Unit Display and not driving the Motor to the Wheel Mount.
Here are my symptoms:
1) Unit On in "STANDBY" mode never reads "Low Battery"
2) When Engaging "AUTO" mode, "Low Battery" comes on in 15 to 30 seconds after the "AUTO" mode is switched on.
3) Pressing "STANDBY", While "Low Battery" is showing, clears the "Low Battery" message and puts "STANDBY" back on display.
4) In the short time after I push "AUTO" and then +10 several times to change heading, drive motor does not spin. Tested motor with 9V and it spins well.
5) Pulled off connecteor to head unit from both drive and power, inspected, and then reinstalled. Minimal corrosion seen.
Did not test voltage to unit from battery because VOM wasn't working (dead battery).
Unit worked well last year and then quit about halfway through season.
I will look at the resistance measurements given by CaptainDan 99 next, but I am frustrated that I can't get this thing working. IF I have to replace the head, can I do so without a new flux gate and wheel drive?
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