Even though newer vehicles can be complicated to diagnose and repair (and very expensive to misdiagnose) it’s still very possible – and often profitable – to do the work yourself rather than send it along to the dealership to be fixed.
True, dealership technicians often have access to special tools and help from technical assistance centers to make diagnosing and repairing challenging problems easier, but quite often seemingly complicated problems can be repaired successfully without going to the dealership by using a good scan tool, detailed service information and with vehicle-specific wiring diagrams, if you’ve prepared for the challenge and done a bit of research beforehand.
It is possible and people do it successfully every day.
Obviously that doesn’t mean it’s a good idea to just open the hood and start stabbing connectors wildly, hoping for the best – in fact, quite the opposite is true. Understanding how possible problems could develop in a system and then understanding what it takes to fix them is now more critical than ever. For example, some newer high-end vehicles will need to have every single one of their modules reprogrammed if the vehicle’s battery goes dead, which can take hours. Yikes! So knowing what you’re getting into is critical to keep work on track and problem-free.
But if you’re facing a diagnostic challenge, and you’ve got a systematic plan of attack, good diagnostic tools and a few clever tricks at your disposal, you may well be able to diagnose and repair the vehicle right in your own bay – profitably and without undue stress or aggravation.
Here are a few tips to help out along the way.
Preliminary checks
True, there are times when sending a vehicle to the dealer is the smartest move – for example, when a special tool is needed, and you rarely service that type of vehicle so it’s not worth purchasing it or getting involved at all – that’s an easy situation to pass on.
But in other cases such as failed emission tests, MIL lights illuminated or communication issues on relatively common vehicles, it’s wise to check a few things before passing on the job. Even a 10-minute inspection can be well worth the trouble.
For example, a minivan came in with an airbag light on and a code stored indicating a problem with the passenger seat sensor. Quickly inspecting the area revealed a water bottle had been jammed underneath the seat, pressing upwards on the sensor, which created a negative pressure signal and set the code. Removing the stray bottle solved the problem. Easy.
In another instance a small, high-end import came in for a complaint of no power on acceleration. A quick check revealed a rodent’s nest in the air filter compartment (a common event for farm vehicles, but this vehicle was always parked indoors at a downtown condo). No sign of the critter, but clearing out the nest and installing a fresh air filter fixed the problem quickly and effectively. Gross, but also an easy fix to complete.
So in other words, it’s worthwhile to quickly ensure there’s no obvious problem with the vehicle before simply closing it up and sending it away. After all, you never know — you may get lucky and find the problem right away.
In particular, during your inspection ensure that any sensors exposed to the elements are intact (not cracked), securely mounted and free of mud and debris. Since so many newer vehicles have plastic front bumpers that catch on concrete curb stones used in parking lots, this is a fairly common area to find cracked or damaged sensors or mounts that affect system operation. Quickly looking at the front of the vehicle can be well worth the time.
And since poor-quality replacement windshield glass can cause problems ranging from noise and leaks to cruise control malfunctions, it’s worth checking for signs of recent replacement if the problem you’re chasing is related to systems that use sensors or cameras in that area. Unfortunately however, fixing the problem involves replacing the windshield again, using parts that won’t interfere with the system operation – not likely something the customer is going to want to hear.
Also look for any recent repairs including any suspicious-looking replacement parts or harnesses routed at extreme angles that just don’t seem right. If the repairs weren’t done correctly or poor-quality replacement parts were used (or wrecker parts that don’t quite match the system or vehicle) that may indeed be the cause of the troubles. Newer vehicles have very strict tolerances and even tiny differences can affect system operation.
One tip to keep in mind is that from experience it’s usually not a good idea to randomly wiggle harnesses while doing the preliminary inspection on a vehicle with an intermittent problem since shifting the harness may inadvertently fix the problem without actually being sure what fixed it. Wiggle harnesses after the diagnostic tools have been set up so that any fluctuations or changes can be monitored, positively located and the problem can then be repaired so the vehicle doesn’t return with the same problem later on. Come backs definitely aren’t good for business.
| Five things to check before sending a vehicle to the dealership |
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And, as ever, look for poorly installed alarm systems, lighting systems or accessories that may be causing problems. These systems can actually keep causing problem even after they’ve been removed, if the removal wasn’t done carefully. One customer had an intermittent no-start condition on his Toyota RAV-4, which was traced to an alarm system with a remote starter that a friend had attempted to remove for him a few months earlier. The harness was so badly damaged it took hours to repair, but afterward the problem was indeed fixed and the vehicle’s intermittent no-start condition never returned.
In addition to looking for any accessories that have been installed or modifications to existing systems that may be causing problems, it’s worth checking to see if the vehicle’s software was changed to increase or modify engine performance in some way. Thanks to the internet, do-it-yourselfers can reprogram their own vehicles quite easily, and the results aren’t always as flawless as expected. It pays to quickly check early on in your diagnosis.
And also make sure to check all of the fuses in all of the fuse blocks, on both sides of the vehicle and at both ends of the vehicle, especially for problems that involve modules communicating with each other. Newer vehicles have an awful lot of fuses and checking them all is critical. It helps to look at the entire wiring diagram to make sure you’ve inspected them all, not just the little section that’s often included with a description of the system. This will also show all of the fuses and splices in a circuit, too. You may need to hunt or click around a bit to find the complete wiring diagram, and it may help to print it all off, tape the pages together and use colored highlighters to trace the circuit completely from power to ground, but it can make finding the problem much easier. Turning away a job that could easily be fixed by replacing a hidden fuse is not a good idea.
Additionally, make sure any sensors inside the vehicle haven’t been covered up by coffee holders or papers or the like and that nothing is physically interfering with (or spilled on) critical parts of the system. Humans and environmental issues still do find ways of disrupting even the most intelligent vehicle systems.
And one final point: make sure the system isn’t just operating as it’s intended to. Many systems shut off automatically after a certain amount of time or won’t operate when it’s raining, snowing, in 4WD, or the ambient temperature isn’t within a certain range. Reading the owners’ manual or the description of the system operation can prevent chasing problems that don’t actually exist – and also prevent expensive embarrassments.
TSBs, programming updates, tech tips and pattern failures
If the preliminary inspection doesn’t identify the cause of the problem, there are a few more diagnostic tricks that may pinpoint a problem so you don’t need to send the car away – if you have a good scan tool and good service information at hand.
One important note though — it’s wise to make sure the battery doesn’t go dead during diagnosis or repair because the battery may then need to be replaced (not simply recharged), and the customer may not be happy about paying for it. One customer took his Equinox in (to the dealer) for a no-charge programming update and was handed just such a bill for a new battery when it couldn’t be successfully recharged after the repair. He wasn’t impressed to say the least.
Actually, checking battery voltage and strength beforehand is an excellent idea anyway since even a difference of .1 v below specification has been known to cause problems with the electrical systems on newer vehicles. In other words, any battery problems need to be fixed before any other diagnosis happens to avoid wasting time and resources, and it’s best to know this right away. A good battery is essential for the vehicle to operate correctly.
From experience, many of the diagnostic challenges that roll into service bays can only be fixed by replacing or reprogramming modules (or replacing and then reprogramming modules), so checking for applicable TSBs and updates early on is critical. Since customers also use the internet and know this, it’s wise to ensure that a wrecker, alternate source or donor module hasn’t been used in an attempt to save money and fix the problem frugally. The modules might not be compatible or programmed correctly and any problems you’re chasing may be result of the frugal fix.
This issue of mismatched modules might come up if you’re using global scan tool data to see if any codes are present rather than specific scan tool data that can help diagnose problems and monitor parameters. Global data is quick, but it’s not what you need for complicated diagnostic problems. Take the extra time and get specific data for the vehicle. Understanding what the tool is telling you and how to test systems is essential to fix the vehicle correctly the first time.
One experienced technician who works on a dealer’s help line has said a few times that too many technicians still look at a scan tool like it’s a Rubik’s cube, and it simply doesn’t need to be that way anymore. Scan tools are there to help, and there’s more information available than ever before (some phone apps can even do output tests) and it’s just a matter of practicing and learning what to expect from the equipment.
However, in the interest of saving time be sure to check for service tips for any pattern failures that have been identified. The reality is that these simple checks save time and can help quickly pinpoint a problem so you can fix it quickly and go on to the next challenge. Diagnosis can be tough, so it’s wise to use all the resources available to get the job done quickly.
Wiring diagrams, pin and terminal grip and integrity and related problems on the vehicle
If all the modules are communicating and the programming is indeed correct and current, there are still a few more things to check before sending the vehicle away, in particular checking known problem areas like connectors and splices.
In the old days, diagnostic techs used to check the ground straps and ground bolts when chasing hard-to-find problems. That’s still excellent advice, but from experience tough-to-find problems are now more commonly caused by poor terminal grip and issues that develop between connectors and splices rather than from resistance in ground paths, so if you’re chasing a problem that’s tough to locate, it’s worth checking the connectors carefully.
Connectors on newer vehicles can’t take being disconnected and reconnected more than a few times before the pins lose their grip and problems develop. Additionally, the tiny micropins used in many body harnesses have been known to actually break off and get stuck together, creating intermittent problem as they shift around inside the plastic housing. Visually inspecting connectors for damage and checking that the connectors still grip may identify tough-to-find problems without sending the vehicle to the dealership to get fixed.
One good diagnostic tip that might help is to make note of any other symptoms in the vehicle and then use the wiring diagram to check if any of these problems share a common element such as a pass through, junction block, connector or splice. If so, it’s worth investigating the shared area a bit more closely because the problem may indeed be in that area.
And if all else fails, swapping in a known good part from another vehicle or another location on the vehicle may not be a glamorous strategy, but it’s an old trick that still works to locate tough-to-find problems (this doesn’t apply to programmed modules, they often can’t be switched between vehicles without causing big problems).
For example, swapping the location of a suspected bad ignition coil to see if a misfire moves can be helpful and conclusively diagnose the problem. Or swapping extremely expensive headlight components from side to side (if possible) can help pinpoint a faulty component before ordering a new one. Swapping is definitely not a strategy techs brag about, but it’s often one that’s effective and one many dealer technicians themselves have used at some point to save time.
Sometimes the old tricks are still the best tricks, even on newer vehicles.
Conclusion
It makes financial sense to send certain jobs to the dealership rather than wasting time and resources fixing them yourself – but that’s not always the case. In fact, certain independent repair shops make excellent money by taking on the diagnostic challenges dealers don’t want to tackle (or have given up on) and fix them successfully and accurately with minimal problems. It’s not always easy, but if you’re up for the challenge, it can quite profitable. Just be sure to use a good scan tool, vehicle-specific service information and understand the systems involved and what can go wrong before you start. Perform a good preliminary inspection, check for TSBs and programming updates, use the scan tool data and wiring diagram strategically, and test the things that commonly go wrong such as pin grip and bad connections.
You never know, you may surprise yourself with your diagnostic ability and improve your bottom line in the process.
