What does the yellow cog light on the dash of my 1999 BMW Z3 mean?

it is reporting of a problem in the transmission that needs attention. run the fault codes and have the transmission serviced asap.

sometime the gear inter mesh is not accurate.

check the transmission fluid if bad then change it and the filter if it has one if that dont fix it then you have a transmission problem someone in the transsmison

It could mean a number of things. If the light is on you need to take this vehicle to the dealer for diagnostics. Usually its a problem with the computer, wiring, or sensors. The dealer has the tools to perform the diagnostics.

If it looks like the symbol in the image below, it is your brake pad wear sensor.

Your front or rear brake pads are probably worn out (and are below the minimum thickness) and need to be replaced.

Or the wear sensor could be faulty and need replacement also.

There is nominally a fuse, relay, and a switch associated with your reverse lights. Possible repair listed from 'easy to hard' by escalation

easy:
disconnect your negative battery cable, check the fuse block. It should be a 20A fuse(#F203). Some models use a 10A fuse(#F26). Replace as needed
Reconnect the battery, test.
if that doesn't work...

moderate.
have already checked the fuse, check to see if you have a "reversing light relay" (K6325) (My 2001 z3 does not) If present, disconnect negative battery cable and replace the entire relay. It is not worth trying to refurbish them.
Reconnect the battery, test.
if that doesn't work...

hard...
If both the fuse and relay are in good order, it is likely a fault in your wiring or the "reversing light switch"(S8511)

On the manual transmission:
The switch is located on the left of the gertrag transmission
The switch is located on the right of the ZF transmission

unscrew the switch from the transmission
install the new switch, tighten to 15 ft-lbs torque

On the automatic transmission:
If replacing the fuse and relay did not work there is an issue with your transmission range switch, various shift solenoids, shift linkage, etc. I highly recommend a dealer or qualified facility's examination.


I hope this helped!

That cog lite IS the transmission service light.

Change the fluid and filter. Don't do it yourself or have the monkeys at Jiffy Lube do it. They'll screw it up.

Gear with ! (Automatic transmission)
Yellow warning lamp = The transmission is malfuctioning. Avoid heavy loads. All of the selector lever positions can continue to be engaged; in the forward drive positions, however, the vehicle will be operating in a restricted gear range only. Have the system checked as soon as possible.

No, this is a situation that involves one or more of the shift solenoids that are inside the pan. These shift solenoids are malfunctioning at this time and, i recommend inspecting the transmission asap for faulty solenoids.

bmw's are user friendly prob. means change trans fluid.