You're not serious! You're kidding me right?

Early on in my career I used get amazed at the number of issues and concerns that I would encounter in the automotive world. I found myself saying on a regular basis "Just when I thought I seen it all." Those are the moments, especially when you find the cause of the fault and its not what you expect. There has also been a occasion or two when I simply had a good chuckle about some experience's. It is such a moment that I wish to share with you all. Hopefully you will gain some insight, find a bit of wisdom to add to you diagnostic arsenal and have a chuckle or shake you head in disbelief with me.

A few months back I was at a shop for a run of the mill blind spot module static calibration. Due to repairs completed on the quarter of vehicle involved in a collision. I showed up onsite because a co-worker was having trouble communicating with the vehicle. The frustration on his face was pretty obvious as he explain to me several basic features on the Toyota Sienna were inoperable. He also informed that at first it was impossible to get the vehicle to start without a jump too. So the shop had installed a new battery almost 40 minutes prior to my arrival. Now that the Toyota Sienna hybrid could start and move on its own but it had several other issues. I looked at his scan tool and noticed the amount of ecu's offline by a simple dash next to each module instead of reporting back no communication. This meant that the scan tool was reporting back that over 20 modules were not installed at all on this vehicle. According to the scan I was looking over the BCM, Door lock, ABS, HVAC or Navigation/Infotainment Module amongst too many others to count. Forget no communication! They were not installed period! In disbelief at what I was seeing I went to grab my Autel and then OEM TechStream. Which stated make sure the key is in the on position and vehicle is connected to a VCI(vehicle communication interface). Both reported back the same results. I blurted out loud "This makes no sense, its Impossible!"

I placed all the scan tools down on the driver seat then took a moment to organize my thoughts. The bits of information and symptoms I had observe so far began to fly around and collided into each other building one plausible scenario after the next. The synapses in my mind fired in a fury similar to a stage 4 hurricane one bit of information tossed then another. Until finally the storm had calmed and a diagnostic approach based on all the information I had gathered thus far was created.

I turned calmly and looked at my co-worker "You have three possible scenario's here that can cause this many faults across several Control Modules. A lot of blown fuses/One big fuse 60amps are better, crushed Can Bus network circuit or a missing ground.

I pulled up a schematic and found which fuse was responsible for the door locks and windows. Its location was in the driver footwell fuse box and as I suspected it was indeed blown. This did not help me be able to communicate with the vehicle but it did confirm that one of the three scenarios I came up with was a probable cause. The 10amp fuse to the 16 pin Data Link Connector was actually fine so that was definitely not the issue here.

I needed one more concrete piece of evidence that a major power supply blown fuse or two was the cause of the no communication with any scan tool.

I normally carry a breakout box on me so this was not out of the norm. After digging through my work vehicle I returned with a big grin and my special break out box in tow. My co-worker looked at me in disbelief "I don't get what is that supposed to do."

This is yes a breakout box for a DLC but also is meant to power up and program nearly any ECU separate from a vehicle. Seconds later I was plugged into the Toyota DLC and my break box was plugged into the wall socket. ALL three switches were flipped on the GODIAG box and within minutes for the first time after about 30 minutes of nothing. The ms909 scanned all available control modules giving me more direction.

As I pulled up a couple of schematics to cross reference I pinpointed the fault down to the PBD ALT1 120A fuse in the under hood power supply box.

The shop ordered a new maxi fuse array and when I returned days later to install it I discovered this was not a stroll in the park job.

After this Fuse assembly was replaced there was still P056014 System Voltage short to ground or open reported as current in the Hybrid Control Module. Needless to say this fuse was blown too!

After the replacing the final fuse I thought to myself I know what the cause of these fault were but what was the root cause. Pulling the schematic back up and looking at the repairs done by the shop. It clicked immediately I knew what was the actual root cause of this crazy electrical mess. I just needed to ask one question the young man who repaired the right rear quarter confirmed that he had been welding. The original 12v battery was not disconnected and no surge protector was ever used. This explain why a vehicle that was drivable needed repeated jumps after completion of repairs. Also how 4 fuses including a 120amp one was blown. I was utterly shocked to find this out. I walked away muttering to myself over and over "You gotta be kidding me !!!!