Wiring and Connections

In my daily travels to shops I get to see some interesting issues. I uncover some interesting wiring issues daily. Some are natural and some are natural with some human help so to speak. I used my human senses and brain power more than my other test equipment to find these issues
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One of my really good customers calls me to tell me he has a 2008 Ford F250 that has an intermittent no crank condition and the customer reports that when the vehicle is in this no crank condition the dashboard has all the warning lamp illuminated.

I arrive and the truck starts and runs like clockwork. This happens all the time. I scan all the modules with Ford IDS and there are many communication codes dealing with the CAN (Controller Area Network) network. A quick scope check tells me the CAN network is operational right now. I look at the modules involved. I see that the CAN wiring runs throughout the vehicle. I give a visual under the hood for anything rubbing or a harness that is not secured. Looks pretty good. I then see the CAN wiring runs down each rocker panel. This truck is definitely a typical Northeast plow truck work horse. I pull up the passenger side sill plate.

Yikes! There is dirt, leaves, and not too much left as far as the rocker panel itself. I literally dig out the wiring harness and surprisingly it is in good shape. I cannot find anything wrong. Well if this side is like this what does the other side look like?

 Just as bad if not worse. I can immediately duplicate the issue as well by moving the harness. You can see the issue barely in this photo. Lets get closer.

Here it is. Between the water intrusion and the dirt it wore one of the CAN wires and corroded it. I repaired this wire and a couple of others. I advised the shop to vacuum out both side sill plate areas. Unfortunately, this will happen again due to the rocker panel area being rotted. The fact that the customer likes to run this vehicle into mud up to the doors multiple times doesn't help at all either.

Next up is a 2012 Toyota Camry that is at a body shop. The owner of the shop tells me that the vehicle was actually in an accident a couple of weeks ago and was repaired at another shop a couple of hundred miles away. Recently, it has developed a couple of strange issues. The vehicles cooling fan runs all the time, headlamps illuminate when not requested, and most troubling is the vehicle will start on its own and won't shut off! The car owners insurance suggested this body shop to rectify the situation. That is when he called me in.

I have been down this road before with these vehicles. In fact there is a TSB from Toyota concerning this issue. I printed it out ahead of time so I could give it to the body shop. I arrive at the shop and the shop owner is reviewing the issues with me. I pop the hood remove the cover from the underhood fusebox and I am greeted by the unmistakable smell of burnt electronics. As the owner is talking to me I wiggle up the Integration Relay in the underhood fusebox.

That is a hole burnt right through! Now the whole shop has the burnt electronics odor emanating throughout. The body shop owner lets out a couple of descriptive expletives and calls everyone over to look at the relay. Next lets look at the wiring.

That bare wire in the photo is not supposed to be bare. The heat from the amp load burnt off the insulating jacket and left a bare conductor. The reason is carefully laid out in the TSB. The vehicle grounds are attached to a support. Typically, a body shop will undercoat or paint these supports and often times insulate the grounds causing a voltage drop. The TSB wants you to expose the support sand and use new redesigned bolts. But, we will still need a underhood fusebox, some wiring, and a new Integration Relay. I leave the TSB with the body shop to use as a guide.

Next is a 2004 Dodge Ram Truck that the owner said just died out and now is a crank and no start. The shop checked for PCM communication and had none. They also check for spark and had none. I arrive and confirm the no communication with the PCM. I check for proper 5vref and have a strange fluctuating voltage that never reaches 3.0 volts. Ok, maybe I have a sensor that is loading the 5vref line down. This is pretty common. A couple of minutes later all sensors on the 5vref line have been disconnected and I still don't have a solid 5vref. Lets check powers and grounds at the PCM. I pull a wiring diagram and verify proper powers and grounds. Did this PCM go bad? Looking that way. I have been burnt before with JTEC terminal tension. I pull the PCM connectors to do a pin drag test and quickly see my issue.

That green spot is supposed to be a terminal. A terminal that supplies power to the PCM. Where is the terminal?

There it is stuck in the PCM connector. Now, this vehicle is going to need a PCM and I am going to have to do some micro surgery on the PCM connector and replace that terminal. The terminal that rotted is at the bottom of the PCM. Somehow, water got into the PCM harness and laid there and rotted that terminal out. In talking to the owner this vehicle was in an accident years ago and sat for a long time before he bought the truck. probably with the hood off. Maybe then?  

I have had quite a few emails lately. I will be answering them all real soon.