This article is directed towards a Chrysler Minivan that I had in the shop the other day with a strange problem that I have seen a few times before so I wanted to inform others about this problem. The problem starts from a simple issue you would never expect to lead to this. Take a look at the cut open wire harness below.
Here you can see that there is obvious battery acid corrosion that deteriorated the insulation of the wiring. Even though at this point you may not know what this wire harness is for you can tell that this would cause an obvious problem, no matter what it’s for, huh?
The picture you’re looking at above is the main wire harness for the fuel injectors. The injectors are supplied battery positive through a common wire and they’re energized by a ground control through the PCM (powertrain control module). These wires are shorting out on the ground control side only because if it shorted on the power side the vehicle would just not run, would blow a fuse or burn up a fusible link. That would actually be easier to diagnosis because the picture of the wire harness above actually caused an intermittent problem for years before it actually failed to the point were the customer had to tow the vehicle in to my shop.
On theses Chrysler vehicles it’s common to see this type of battery corrosion at the positive and negative battery terminals and cables. The way the cables are sealed you usually will not see the corrosion unless you cut open the battery cable. The battery acid eats at the wires like cancer and will follow all the way down through the harness. Now a year earlier with this same customer we had an alternator and battery failure and I found this same corrosion in their battery cables. I had fabricated new positive and negative cables, replaced the battery and alternator and though nothing else of it once they started having the misfire issues caused by this fuel injection wire harness. I believe that the neglected battery cables caused the corrosion to grow down the harness. Keep in mind that old battery’s that are starting to sulfate will cause this also so keep a good battery in your vehicle and keep the terminals clean. You can use either baking soda & water to clean the acid or buy a special cleaner from the auto parts store. Once your done cleaning the battery parts make sure to seal them with either dielectric grease or a battery terminal sealant that comes in an aerosol can.
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