Peugeot 807 we was called out to due to the powered steering becoming very heavy and the customer wanted the fault comfirmed 100% what the fault exactly was. There could be sevral causes which would stop the electrical powered steering pump working and as such we checked every possible reason.
First we got directly to the powered steering pump. Checked live and earth and these were found to be good / ok. we then checked the ignition feed to make sure this was waking the pump up correctly. This also checked out all ok and the final test was making sure the data was being sent to and from the powered steering pump back to the vehicles ECU / BSI. This data system is known as Can-Bus.
We linked up the scope and confirmed a good / correct can-bus wave form was present and then could confirm 100% it was the powered steering pump that needed replacement. The customer wanted us to confirm it was the pump, due to how much a new part is from Peugeot and the vehicle being older. It is wise they didn’t want to gamble / risk a new pump not fixing the issue.