buzzer sounds in reverse - PeachParts Mercedes-Benz Forum

lowriderdog37 · #1 08-26-2007, 10:09 AM

I just changed the tranny fluid (including tq converter) and filter last night. I put mobile 1 synthetic ATF in it. The dipstick is showing that there is plenty of fluid in it, but periodically when I put the car in reverse, the buzzer in the cabin sounds. I turned the car off and took a few (maybe 5) minutes to clean up my tools, then turned the car back on to move it...no buzzer.

It is only sounding when my foot is on the break and in reverse. I haven't had much time yet to test it more thoroughly, but thought I would ask anyway. Any ideas?

Breakdown of events:
Drained pan
Took pan down
Drained tq converter
New filter, new gasket
Replaced pan, drain bolts
Poured 4 qts of ATF
Started car, ran through gears, pulled off ramps (buzzer sounded)
Poured 2 more qts of ATF
Checked level and poured 1/2 qts again
Checked level and poured 1/2 qts again (level good)
Went for drive (no buzzer when in reverse)
Turned car off when back at home
Turned car back on to move (no buzzer in reverse)
Did work on coolant system
Turned car back on to move off ramps again (buzzer sounded)
After ramps, buzzer still sounded
Turned car off, cleaned up tools
Started car again (no buzzer)

Like I said. I haven't found too much of a pattern yet, but I'll keep an eye out.

Jeremy5848 · #2 08-26-2007, 12:18 PM

(a) What kind of a car are we talking about here? (Hint: Put the year and model number in your signature.)

(b) Which buzzer? What other things cause the buzzer to go off -- headlights, key in ignition when door opens, etc? There's a lamp and warning relay in many Benzes that could be causing your problem (if you have a Benz

). It's electronic and complicated and connected to lots of things.

lowriderdog37 · #3 08-26-2007, 12:29 PM

Yeah, I forgot to put that in...didn't I. I have an '85 300CD. The only other time I have heard the buzzer going off if for about 8-10 seconds when I turn the key on (to warm up the glowplugs) and when I don't have my seatbelt on.

carnut · #4 08-26-2007, 01:27 PM

Still not in your signature!!

Jeremy5848 · #5 08-26-2007, 02:34 PM

Quote:

Originally Posted by lowriderdog37

Yeah, I forgot to put that in...didn't I. I have an '85 300CD. The only other time I have heard the buzzer going off if for about 8-10 seconds when I turn the key on (to warm up the glowplugs) and when I don't have my seatbelt on.

OK, that's the relay I mentioned earlier. It's most likely that a wire is shorted to ground or to another wire. It may have happened during the work you listed or may simply be a coincidence. The relay is connected to all sorts of things -- door switches, key switch, lights, etc. -- and can appear to be malfunctioning when in fact it is only one of the wires is damaged.

On the other hand, the relay itself does fail -- my '87 had such a problem.

Look for any wires that might have been pulled loose or damaged when you did your work.

Jeremy

lowriderdog37 · #6 08-26-2007, 11:46 PM

Thanks Jeremy, that was what I was hoping to hear. I didn't know if the tranny just didn't like what I was trying to do to it. I will chase the wires down sometime in the future...it doesn't really bother me too much at the moment after knowing it's not something serious.

By the way Carnut, I did put it in my signiture, but it didn't post yet. I am glad there are guys like you going around helping with the important stuff. We would never get anything productive down around here without you. At least Jeremy was nice about it.

Jeremy5848 · #7 08-27-2007, 12:03 AM

You and I have the same car, more or less. Under your driver's seat is a plug-and-socket on cables. if you unplug them, the buzzer won't buzz if you don't fasten your seatbelt. Just let them sleeping dogs lie and if you ever want the buzzer to work for seatbelt, just plug it in again.

I always wear my seatbelt but I like to turn on the key first and let the glowplugs do their thing while I do the seatbelt. By the time the belt clicks, the engine is warm enough to start. But I hate listening to the buzzer while I reach for the belt (locking the door as I do so) so I disconnected that plug.

The headlights-on function, on the other hand, I use all the time.

I'd have a dead battery regularly without it.

The buzzer relay is expensive, at least $50 I think, so you may choose to live without, if it turns out to be more than a disturbed wire.

Jeremy

bustedbenz · #8 08-27-2007, 12:33 AM

mine buzzes when I step on the brake with the door open, any gear.

lowriderdog37 · #9 08-28-2007, 11:11 AM

Yeah, I am going to unplug that wire under the seat. I haven't heard the reverse buzzer at all the the last few days. My favorite kind of problem...the one that fixes itself.