Let's see if this needs to be addressed:
If you discover that the cleaning chemical you used to cleaned the truck was wrongly labelled and actually it could potentially harm the food that is being transported in that truck. What would you do?
You need to notify your customer immediately to let them know which trucks are affected, so you need to have a procedure in place to correct this issue.
1. Can you identify which truck have been cleaned with wrong chemical?
2. Do you have a registry of cleaning e.g. Truck with a licence plate XXX 123 has been cleaned at this date, at this time by this employee by using these chemicals?
3. Does any of the chemicals you use can be potentially hazardous to health if they are to come into contact with food (consider for example when driver is emptying the truck, he dropped the tray of croissants on the floor and he said "naa I willl just pick them up put it back on the tray" do you reckon the food will be contaminated because of the contact) even though it is beyond your control you can assess this in your HACCP study. So one of your controls could be "choosing less harmful chemicals" for cleaning.
These what came up my mind, but I think you get the idea about how to approach the traceability and recall clauses.