Help - autobox sticks in safe mode

[richard7mad]

Any ideas?
My e23 3.5 1985 sometimes goes into safe mode so that only reverse and third? are working. It has done this for up to a week, with a yellow warning displayed. It will then return to normal, in an apparently random way, at some time - so far!
Advice gratefully received.
Richard :(

[shogun]

How is the battery doing? Too low voltage can also show such fault.
Check the battery voltage and the charging voltage of the alternator.

[richard7mad]

have checked the battery today and it seems ok(13.5v on my meter 13.7v when running) but i did have a fault with a intermitent window motor conection which seems to cured its self. is there a conector or somewhere i should check voltage other than at the battery

[shogun]

Find a digital multimeter and stick the probe into the cigarette lighter socket in the center console.

The following are the detail figures I use for my own evaluation:
With key out of ignition switch, should see 12.4V or above. 12.0 V is getting low.
With key inserted and turned to position 2 (don't start car), should see 12.0V or more. 11.6V would be too low.
Crank car, catch the lowest voltage reading during that couple of seconds. Should see 10.0V or above. 9.5V would be marginal.
The above just consider the health of battery itself.
Car running at 1500 RPM or more, should see 13.7 to 14.3V, 13.6V or below means the charging system is weak.