I bought an 86 w250 and I've found my reverse lights do not work I don't know where to start and having trouble figuring out the wiring .

 

Manual or automatic trans?

 

Sorry for awnsering late I've been to busy with work but it is a manual transmission I do not know how to test the reverse switch on my Trans but my wiring in the rear has been torn apart by the previous owner also trying to find the wire colors to hook up my lisence plate lighting aswell

 

Have a look here. Should help.