Have tested bulbs in backup light sockets. No power to reverse lights. Where does one begin the diagnostics procedure?

Did you check the fuse? Just making sure the obvious has been taken care of.

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reverse switch hookup on the tranny

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1995 E420 Schwarz
1995 E300 Weiss
#1987 300D Sturmmachine
#1991 300D Nearly Perfect
#1994 E320 Cabriolet
#1995 E320 Touring
#1985 300D Sedan
OBK #42

Fuses A-OK. 1st thing I checked after bulbs.

Do you have a test light? You can start at the light and work your way back to the tranny switch. I would suspect a ground problem as these things easily get corroded.
bb

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For Sale: 1982 MB 300TD
1995 Chevrolet Suburban 6.5TD

Sold: 1980 IH Scout Traveler- Nissan SD33T Diesel

I suspect it's the switch on the trans, as mentioned already.

That's what fixed my reverse lights on my 80.

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-justin

1987 300TD, 1987 300TD
2008 R32, 2000 Passat Wagon

I second the opinion. I have replaced a few of these for that problem.

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My Truck.. 2007 DODGE, 5.9 Cummins, 6spd stick, 4X4. My car..1977 240D, OTHER WHEELS...1955 VW Oval window bug, European Delivery (Holland) with a 1700cc, 2 barrel, Porsche drum brakes. 1939 WILLYS Pick-up. 1967 Triumph 200cc Tiger Cub. 1976 Honda 550F 4cyl Motor Cycle.

Where to start? With a wiring diagram.

Figure out what else is on that circuit. Check if it is working OK or not. Start at the fuse and work toward the failing taillights. Wires don't fail terribly often so check if other stuff works upstream and downstream of every switch and relay. If you have places where the wires bend, then they can break at that point, so consider those points and make sure stuff works upstream and downstream of them. Lastly, suspect any plug connectors in the wiring harness (not all are usually shown on the wiring diargrams).
Good point Bajaman -- check the ground too.

Or.. break out the test light and do the same -- check upstram and downstream of every switch, relay, wiring flex point and plug connector with it.

Or... take a guess and start replacing stuff that is the most likly culprit.

However, especially on older cars, sometimes the problem is not with a worn out switch -- it can be 20 years of vibration or corrosion someplace.

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