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​How OLDCART Can Help You And Your Tech Find Problems

By Fernando DeMoura

October, 2019

In last month’s article I mentioned that communication between the operator and the technician can be beneficial to diagnostics and ultimately fixing the problem but sometimes it can drop the efficiency of the job and end up making the job more expensive. This month I’ll to expand on what information the tech needs to have the best chance at finding the problem efficiently. 

The most challenging problems to find are problems with intermittent come and go symptoms. If the problem is always observable or easy to replicate, then it’s just a matter of time before the tech zeros in on the problem. If your truck isn’t showing any symptoms of the problem when you bring your truck in to the shop, then the tech has nothing to track. He might say there’s nothing wrong or worse he’ll guess and throw parts at it leaving you to assume your problem is gone even though it was never actually found. Its jobs like this when communication between the operator and the technician can make the difference between you leaving that shop with a successful repair and you leaving the shop with the same problem you came in with. Unfortunately,most shops don’t let you talk directly to the tech who’ll be looking for your problem. Instead you talk to a service writer who will hopefully ask you the right questions and pass that information on to the tech through the work order. So…what are the right questions? I like to look at examples of diagnostic processes in the medical field because they are without a doubt the most developed and efficient problem finding processes we have. Physicians use the acronym O.L.D.C.A.R.T. as the framework for the questions that are asked of Patents that are useful in diagnostics. I use my own version of O.L.D.C.A.R.T. when I ask an operator about the symptoms he observed. Here’s an example. 

O Onset of symptom: When did the symptom start? Was the truck recently in the shop?

L Location of symptom: What RPM and load range does the symptom occur?

D Duration of symptom: How long did it last? Did it happen more than once?

C Characteristics of symptom: What did you see and hear? Smoke from the stack? Low power?

A Aggravating factors: Is it more likely to act up in the rain? On cold start? 

R Relieving factors: Does the symptom go away when you shut down and restarted the engine?

T Treatment tried and timing of symptoms: Did you try changing the engine wiring harness?

These questions will change a little depending on the symptom but providing the answers to these questions can save you time and money as long as the tech is willing to look over your notes. If you’re sending in an ECM for diagnostics the first question,I’m going to ask is how the tech determined the problem was in the ECM. 

Written by Fernando DeMoura; Diesel Control Service. Phone 412-327-9400 Website: