Keith,
I just replaced my coach so I know the problem is not on the coach side.
Not necessarily so. Very possible that the coach socket is wired differently than the toad plug. Here's what I would do:
Make a diagram of the coach socket showing the individual pins, and number them. If thepins already have numbers, use those on your diagram.
Next, make a test light using a spare 1157 bulb by soldering one wire to the metal outside shell, and soldering another wire to the pin on the base for the heavier filament of the bulb. If you don't know which one that is, temporarily connect the wire from the shell to the minus (-) of the battery, and connect the second wire to the + terminal of the battery, and carefully touch the other end of this wire to each of the two pins on the base of the bulb, and note which one makes the lamp burn brighter. That's the one we want. Disconnect the wires from the battery and finish your solder connections.
Now for the fun part
Take one of the wires from your test light (doesn't matter which one) and attach it to a good ground on the coach, and use the other wire to probe the pins of the connector. Start by having someone step on the brakes while you probe the connector to find the pin that lights your test light. Mark that pin on your diagram with the word "brake". Do the same for the taillights, and right and left turn signals, marking the pins on the diagram appropriately. We also have to find the ground pin. Turn off all coach lights and make sure nobody is stepping on the brakes. With a multimeter set to ohms and one of the test leads connected to ground, measure the remaining pins (those not associated with any of the lights on your diagram) and find the one that reads zero (0) ohms. Don't be fooled - several of the other pins will read CLOSE to zero, but only the ground pin will read EXACTLY zero. Note this pin on your diagram.
Now, armed with your annotated diagram, go to the toad. Attach one wire from the test light to a good ground on the toad, and touch the other wire to the pins corresponding to your diagram, one by one, while someone watches to see if the proper light(s) are coming on. See note** On your diagram, make a note of any pins that are not correct, i.e. wrong light comes on or no light comes on. In the case of the wrong light coming on, find the pin that IS the correct one and make the necessary change(s) to the plug wiring. Again using your multimeter, check for the ground pin just like you did on the coach. Must be zero (0) ohms and must match the ground pin on the coach.
note**
The lights will be quite dim because we have our test light in series with them, and they aren't getting the full 12 volts. We're doing this because of the possibility of shorting to ground - something we definitely don't want to do. Best to do it in the shade.
Based on your symptoms, my guess is that the ground pins are not matched correctly. You may want to check that first, but if it's not correct, at least one of the other pins also won't be correct.
Good luck, and report back with your findings.
Almost forgot: Did you wire protection diodes into the lights on your toad????
