QuestionI replaced the 2 oil pressure sensors in my 1996 2.0 Volkswagen Jetta. I also had the oil pressure checked and it was ok. I was wondering what the problem could be. If anybody has any similar problems and can maybe help me out. It would be greatly appreciated.
AnswerI wonder if the wiring harness that feeds, and retrieves information, and power to your sensors could be shorted, or more likely, unable to find a consistent reliable ground. Strip, cut, or pull the old insulation off of the wiring harness that goes to your pressure sensors, and look for corroded, or nearly broken wires. Also, track down your ground connections to the chassis/body of the car. The one on the hood is already broken...they all are by now...
This may seem time consuming, and fruitless, but your time invested will be far less money out of your pocket than paying someone else to find a broken, or corroded wire. After all, the car is 11 years old, and has been heated to 212 degrees F, and beyond how many times now? Wiring insulation, etc. is good, but not good eternally.
I hope you find it/them...How many different owners? How many different stereos? How many different wiring additions through the "bulkhead/firewall?" Do all other portions of the instrument cluster work perfectly? It could even be a bad ground connection through the cluster.
Volkswagen is not unusual in that they will reduce weight, and materials necessary for construction of a vehicle by grounding certain circuits through other circuits that are still "live" with current. The reason this works is there is far less current demand in the circuit used for ground, than in the circuit using the ground.
I'm reminded of a difficult problem I had to diagnose, and it turned out to be something completely unrelated. It was electrical, and the solution was electrical, but the system was, logically, unrelated.
Turn your car on, let it run, at idle and turn on your headlights, AND foglights, if you have them, switch on the brights, and switch them off, and watch the instrument cluster. If nothing changes, leave the lights on, and car running, and walk around the car and check all, I mean all, of the bulbs, have some one watch for turn signals, and for brake lights too. As unlikely, or as unrelated as this sounds, the oil pressure switch may be grounded through a lightbulb filiment, and if the lightbulb is burned out...No path to ground! I don't have access to wiring diagrams to check this, and I'm not all that familiar with A3's, or A2's, but this is something I have encountered, in at least 2 other situations...one was lighting, but the other one was comfort/convenience, so why not assume the same could be true for instrumentation....Be certain to check for lights in the cluster, radio, and ventilation controls too. Very clever, those "ingeneurs"/engineers!
