There is no easy way to put this, but Ford is one of the leaders at building in totally unnecessary, and unreliable electronics. The moisture, dust, and vibration is the worst possible environment to expect delicate electronics to survive in. To add to the misery, the dozens of computers all talk back and forth to each other, and a problem with one can show up as a symptom for another. In Ford products, the most intelligent computer on the car, meaning the most involved with all the other systems, is the instrument cluster. Nothing happens without him being involved. The cluster is even the first of two computers involved in blowing the horn. The engineers found a solution where there was no problem.
In the case of dim sections on the instrument cluster, that is not caused by anything other than a problem on the cluster itself. If you do a Google search for "instrument cluster repair", you will find hundreds of listings for places that repair the multitude of GM problems. Most of those places also do the Ford repairs. Some only accept units through new-car dealers' parts departments, but most will accept a cluster from the owner. If you send yours in, it will come back with the same mileage. If they are able to ship out a replacement cluster first, they will program in the mileage, and when necessary, they are usually able to program in the vehicle ID number so you can just plug the cluster in and it will work.
Another source of problems is Ford's "GEM" module, (Generic Electronic Module). That is their name for their Body Computer. That is involved with lights, wipers, seat belts, etc. Basically all the things we had for many decades, but that never needed a computer before. One recurring source of trouble has been corrosion buildup between adjacent connector terminals. Look at that when a symptom occurs when something seemingly unrelated takes place. A good example is the wipers run intermittently when the tail lights are turned on.
The best place to start with this is to find a mechanic with a scanner that can access all the computers, and have him read and record all of the diagnostic fault codes. Even the heater controller is a computer module and it can store fault codes. The engineers tell us diagnosis is much easier today because all these computers detect problems and set fault codes directing us to the circuits that need further diagnosis. The problem is the majority of the problems are caused by those computers and their sensor circuits. Customers today insist on having all the latest technology in their cars, then they do not understand why they have so many problems and expensive repairs.
Saturday, April 15th, 2017 AT 10:05 PM