Over the past few articles I’ve been laying out the basics of electrical diagnosis. In this article I’ll suggest some ways to diagnose intermittent problems with your customers vehicles. You may want to review previous articles on the six-step electrical diagnostic approach, using a DVOM, or check engine light diagnosis.
Electrical problems that are intermittent are by far the technician’s biggest challenge when it comes to diagnosis. You cannot hope to diagnose and repair something that you can’t see happening. The customer will be unhappy if you “throw parts” at an intermittent problem with the hope of fixing it. So what do you do?
The customer, and your own diligence, are your two best tools when it comes to finding intermittent problems. Collecting information from the customer is critical. Sometimes a customer is able to get better information if they know what to pay attention to, or what to look for.
Although intermittent problems can be frustrating, often just taking the time to try and duplicate the problem can result in a positive diagnosis and repair.
As stated in the Six Step Repair Process, the completion of a Customer Analysis Sheet can help a service writer, or technician, with gathering the information required to duplicate the problem. Information that is useful in duplicating the problem would include:
• How often does the problem occur?
• How long after the vehicle is started does it occur?
• Does it happen only over bumps? If so, what kind of bumps?
• Does weather have any effect on it?
• Does the car have to be idling, driving, in reverse, moving forward, be in gear, etc.?
• Is there anything at all, no matter how crazy it sounds, that the customer associates with this problem?
Using what I call a Customer Problem Analysis sheet can help in collecting this customer information. All major repair databases have these that can be printed out – or you can make up your own. If you’d like a copy of the one I use contact me HERE and I’ll be happy to send you one.
Use it to make sure the right questions get asked of the customer, to refresh the customer’s memory of what conditions the problem is likely to occur under, and to get information from the customer in writing for future reference.
One question that I always ask the customer is this: “Is there anything, no matter how crazy it may seem, that you associate with this problem?”
You just might be surprised at the answers you get! Of course, all questions are aimed at attempting to duplicate the customer’s concern so that a proper diagnosis can be made.
Intermittent problems can be caused by loose wiring, poor pin fit at a connector, partially broken wires, or water intrusion of a connector, switch, or component.
When trying to duplicate an intermittent problem remember that small vibrations and movements are far more likely to duplicate the actual operating conditions than large movements or banging will.
Many technicians will go about searching for an intermittent problem by pulling and yanking on harnesses, thumping on control devices, and driving on the roughest roads they can find. This approach will work as long as the customer says the problem occurs while off-roading, kicking the ECU, or every time they pull on the wire harness!
Gather the most exact information from the customer that you can, and then try to recreate those conditions. The vehicle’s HVAC system can be used for recreating hot or cold related conditions such as the problem only occurring when the vehicle sat out in the sun, or when it was cool out. Water gently sprayed on the vehicle can simulate rainy conditions.
Be patient and diligent when searching for intermittent conditions.
I always advise customers that their vehicle may have to be kept at the shop for an extended period of time so that it can be test driven and exposed to the most likely conditions causing the problem.
Here’s an example of diagnosing an intermittent problem from a case study:
A customer brought their 2007 Toyota Corolla into the shop after putting up with an intermittent “radio cuts out” complaint for 2 years. The radio would shut off (no sound and no display) while driving, or while idling. The radio had been replaced three times with no resolution.
With the vehicle idling in the service bay, suddenly the radio turned off. The technician working on the vehicle thought to quickly try other systems to see if anything else didn’t work. He discovered that the power mirrors also did not work. Before any diagnosis could be done, everything came back on!
With the only clue to go on being the power mirrors were inop at the same time, the technician was able to use the wiring diagram and isolate the problem to a connector deep in the dash, common to both systems.
He found the connector not fully engaged.
Without having noticed a related system also not functioning, the technician would not have had anything to base a diagnosis on. Even with this little piece of critical information, he was able to create a satisfied customer where no one else had.
This example demonstrates not only diligence in locating an intermittent problem, but also shows the benefits of properly using the six-step diagnostic routine!
As always feel free to contact me with article ideas, questions, comments, or complaints! Don’t forget to subscribe to this column to be notified every time a new article gets posted! I can be reached through pingroof.com or by clicking HERE. Keep up the great work and never stop learning!