First-time mistakes in the service bays

April 1, 2017
In this article, I will provide you with real-world shop mistakes that I and others have made. Some are costly in time or parts that both affect the shop’s bottom line; and, in other cases, costly in terms of one’s reputation.

“To err is human; to forgive, divine” is a phrase that you may have heard at one time or another. In the automotive business, however, an error could be very costly and just may not be forgiven by the vehicle or shop owner. In this article, I will provide you with real-world shop mistakes that I and others have made. Some are costly in time or parts that both affect the shop’s bottom line; and, in other cases, costly in terms of one’s reputation.

Our first tale

One of the problems that we encountered in our shop recently was on a 2008 Honda Accord with 125,000 miles that had come back after a timing belt and tune up were performed. The owner returned to our shop because of an illuminated check engine light that resulted from an engine misfire. After the tech connected the Honda factory scan tool, he retrieved the misfire DTCs (Figure 1) along with a P0339 Crank Sensor DTC. It’s never good when a customer returns with any problem after a repair has been recently performed on their vehicle. The return of the MIL light is the telltale sign that the vehicle’s computer system sees something wrong and is going to alert the driver. There is no way, at least with drivability issues, that you can hide from doing it right. So, we had to handle the vehicle owner very carefully and be honest with her on what the problem was. We explained what went wrong and caused the MIL light to illuminate and what we were going to do to make it right.

Figure 1

Before we dive too deep into this misfire and crank sensor problem, a good suggestion would be to read up and understand the DTC description before moving forward. Since this looked like a simple problem that may be the result of possible defective ignition part, the tech performed the usual diagnostic routine. Well, in this case it was a lesson that was going to be learned the hard way. Since many technicians would start testing the ignition and fuel system as their first part of the diagnosis, they would not find the root cause of the problem on this Accord. The next logical step that the technician would most likely perform is checking the crank sensor and possibly replacing it, without repairing the problem. Some of the first steps to perform are having a vehicle owner Q&A, visual inspection, system scan and a (Figure 2) TSB check. In this case, there was a TSB for this Honda that describes the DTCs and lists the potential problems, such as a weak battery that can cause the P0339 DTC. Reminder! It’s also a good idea to check service information and TSBs on every vehicle you work on. After all, you don’t know what you don’t know. My technician checked the crank sensor and the circuit without finding any problems. After checking the vehicle for over an hour, my tech was still baffled on what the root cause of the misfire could be. He decided to ask me if I had any idea what was causing the problem since he could not pinpoint it.

Figure 2

I proceed to check all the basics from the battery, engine mechanical condition, ignition and fuel systems, as well as the CKP circuit, only to find the same results as my tech did. My suggestion was to perform a (Figure 3) Crank Relearn procedure on this vehicle since it’s the procedure that Acura/Honda recommends. I connected the MVCI along with the Honda factory software, showing and explaining the procedure to the technician so he could get a better understanding of the problem. Once the procedure was complete, the vehicle was road tested, then returned to the owner without any DTC or MIL illuminated. We assured the vehicle owner that her engine was in very good condition and all the issues were addressed. We explained that there was really nothing wrong with the work we performed on the engine, but by accident we forgot to perform the relearn procedure. The vehicle owner left our shop with a smile and even called us about 10 days later to tell us that the Accord was running great.  

Figure 3

Lesson No. 2

Our next mistake was on a 2003 Saab 9-3 that had a DTC P1681 Control Module Internal fault that one of my techs brought in the shop for his cousin. After my tech checked all the basics, he confirmed that the problem was in the ECU. This problem on the 9-3 had only one fix for the P1681 DTC and that was to replace the ECU and program it. Since we all know that Saabs are no longer made, my tech went the cheapest way and found a used ECU to install. With the new ECU installed, his next step was to program it with the correct information by updating the programming file. Without asking anyone else in the shop, he proceeded to program the car with a J2534 (Figure 4) tool, rather than using our factory Saab tool.

Figure 4

It’s wasn’t his first time programming a vehicle, but there are some things that he just did not know about programming a Saab. After trying the program procedure two different times without success, you would think he would have asked one of us for some assistance. Not sure why he did not ask, but he decided to wait for the weekend and contact one of my students. Jamie is a good technician that already took his lumps with a Saab and is knowledgeable and helpful, so he showed my tech the correct procedure. Jamie explained that the only way the vehicle could be programmed was with the factory Tech 2 Saab scan tool. When it comes to programming a Saab, you must go through the Tech 2 scan tool and not a J2534 device. Sometimes you just have to ask others for help and not be embarrassed to say you don’t know everything. Once the procedure was properly performed on the 9-3, the vehicle ran great without any DTCs.

On to No. 3

A 2016 Acura RDX came in from one of the body shops we do work for because it was involved in an accident and had two codes stored: BD0090-87 DTC (No Signal from the Left Front Impact Sensor) and B18C7 (Blind Spot System) error (Figure 5, 6). Since this is a new vehicle, the only way we were going to diagnosis it was by connecting our Honda factory scan tool. With the scan tool connected, DTCs were visible along with helpful information on what to check and test right in the scan tool.

Figure 5
Figure 6

As you can see (Figure 6), the BSI (Blind Spot System) indicator problem could be everything from an open in a wire or connector to a bad connection. We decided to tackle this problem first since it looked the easiest out of the two DTCs. We performed all the suggested checks and did not find a problem so we performed a drag test on the BSI indicator connection along with applying Stabilant 22, then retested the circuit. The good news was that this problem was now repaired, but now we had to move on to the tougher of the two problems.

With our attention now directed to the BD0090-87 DTC, we first tried to clear the DTC again only to find it would not erase. This result meant that we had a hard code that was caused by either an open circuit, a defective impact sensor or defective SRS computer as per Acura/Honda factory information. The body shop stated that they had replaced the impact sensor and the SRS computer with new Acura parts. After performing all the system checks, wiring and connector checks, we did not find any issues that would cause this hard DTC. I called the body shop and inquired about the impact sensor, asking if they knew where the old part was. The body shop informed me that the impact sensor was replaced with an updated part number and that they were sure it was installed correctly. I stopped him to ask if he was sure that there was an updated sensor for this vehicle. He replied that his information system that he uses for collision work provided him with that information. I suggested he locate the original part and please drop it off so I could check it out. The body shop located the old left front impact sensor and dropped it off.

While examining the impact sensor we noticed (Figure 7) that the part looked the same but the numbers did not match. For the hell of it, and since we could not find anything else wrong in the circuit, we thought we would plug in the old sensor to see if we could clear the DTC and prevent it from returning. Bingo, the old sensor cleared up the DTC along with removing the message from the dash display. Our conclusion was that the old sensor was good and the new one was either bad or it was the wrong part.

Figure 7

The Acura was not finished just yet. Due to body repair regulations, once a vehicle is involved in an accident, the sensors and computers for the SRS system are required to be replaced. It would now be up to the body shop to contact the dealer and get the correct Left Front Impact Sensor for the vehicle before returning it to the owner. The lesson learned here is never fully trust a part information system or parts guy 100 percent, since the part was obviously wrong. With the new Left Front Impact Sensor installed, the vehicle was back to proper operation with no codes or warning messages displayed. 

And the lessons continue

A 2008 Mercedes Benz ML350 with 254,697 on the clock came in with a bunch of different problems from the common intake manifold to the tail lights staying on all the time. Our customer’s issue with the rear tail lights staying illuminated even when the vehicle was turned off, along with the icon for the rear hatch being illuminated, killed the ML350 battery. The vehicle owner stated he noticed that the lights were not turning off, but since the vehicle started, he just keep driving.

Even though there were other problems on this vehicle we are going to focus on the Signal Acquisition Module (SAM) and explain what it does. Since the vehicle is on a CAN network, the SAM units (yes, there is more than one on this vehicle) control the following: fuel level information, left or right low beams, fog lights, turn signals, doors locking and unlocking, tail lights staying on and other problems. The first thing to look for is always water damage to any of the components that the SAM controls besides the SAM itself. European vehicle are no stranger to water issues, so always make it a habit to check all the drains and clean them out while performing any service on the vehicle. What we found on this vehicle was water damage to both rear lenses, along with some bulb sockets not working. The damage to these rear tail light assemblies was what caused the damage to the rear SAM (Figure 8).

Figure 8

I am happy to report that my technician performed the proper diagnostic procedure, finding the issue with the lights staying on as well the problem with the hatch light illumination. Since the rear hatch door assembly was worn and damaged, he installed a new one. With the new part installed, the hatch closed properly but the hatch warning light was still on. The rear lights were now off and the rear hatch was closing and locking properly, but the mistake was that the SAM was not properly programmed before the vehicle was returned to the owner. So even though all the correct parts were replaced, including the SAM, it had to be programmed or there would still be issues. The tech thought that since the rear lid closed properly and the rear lights were now off the vehicle was fully repaired. Well, we received a call from the ML350 owner complaining that his seats and mirrors were not adjusting to the driver preset position, and they could not be moved manually. We told him to bring the vehicle back in. Once the vehicle was back in the shop, my other technician connected the scan tool and programmed the SAM, making sure everything it controlled on the CAN BUS worked properly. For his inconvenience, we gave the vehicle owner a credit for his next oil change, helping ensure his return to our shop. We explained that the programming of the new module was not executed correctly, and that was causing his seat issue. We performed a checkup of all the vehicle systems by performing a complete vehicle system scan. We provided a printout of the system scan to assure him that all was now good with his Mercedes.

Last lesson for today

Our last vehicle, but I am sure not this will be our final lesson learned, as we are human and most likely capable of making a mistake in the future. This vehicle came to us from a different body shop than the one I mention above with a dash light illuminated for an adaptive headlight issue. The vehicle was a 2013 BMX X5 that had been hit on the right front side of the vehicle. The body shop replaced all the sheet metal including the fender, hood, grill and headlight assembly on the right front side of the vehicle. The body shop thought the only thing that need to be done was to clear the DTC and adapt the headlight. Well, the DTC could not be cleared because this was a hard code for an open circuit. Having seen this problem before, I called the body shop and told them they most likely forgot to remove and install the motor assembly from the old unit to the new replacement unit.

The body shop was adamant that the assembly was install with all the parts correctly. In fact, they were dropping off another vehicle to diagnosis that the owner of the body shop was delivering so he could personally read me the riot act. He said, he was 100 percent sure that I was making a mistake and should just get the headlight coded and clear the DTC. Rather than getting into to a drawn-out argument with him, I assured him we would get the headlight working. After he left, we removed the right tire and fender well to access the headlight assembly. The headlight was installed without the motor assembly.

I called up the body shop and told him that I had pictures, along with access to the headlight assembly, so he could see for himself. I suggested that he look around his shop for the original assembly and bring it to us if he wanted the headlights to work properly. Lucky for him, he found the old assembly in the dumpster or he would be calling the dealer and spending a lot of money on the replacement headlight motor that the insurance company would not be paying for. Once he brought down the old assembly, we showed him where his head tech had made the mistake. We fixed the vehicle, received payment, but did not receive an apology from the body shop owner. We don’t know everything, and we learn something new every day. So, it is not a bad thing to admit when we are wrong and say sorry.

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