Update routes.rb

config/routes.rb

@@ -19,5 +19,5 @@ get 'qbo/estimate/:id', :to => 'estimate#show', as: :estimate
 get 'qbo/invoice/:id', :to => 'invoice#show', as: :invoice
 resources :vehicles
 resources :customers do
-  resources: :vehicles
+  resources :vehicles
 end