My car will not accelerate quickly and the RPMs never go above 3000. After an engine diagnostic, I got an “Error Code P0340: Camshaft Position Sensor”. However, I was trouble shooting the sensor with a voltmeter hooked up while hand turning the engine, and I was getting a 10 volt reading every time the camshaft passed by the sensor. This would indicate that the sensor is working properly. Also, I put the voltmeter across the 1st and 3rd node where the sensor plug is and received a 7-8volt reading without even turning the key into the on position. This seemed strange.
Another issue which might be related, is a radiator fan which will not turn on. All troubleshooting indicated a switch replacement, however after replacing the switch, the fan still does not work. Is all of this pointing to larger electrical issues? Or is the camshaft sensor replacement a sure bet?
The cam sensor tells the engine computer whether the cylinder is on the compression or the exhaust stroke. Without that info it has to fire the spark plugs on both strokes, which is probably why it is limiting the rpm, to prevent ignition module and coil damage. I don’t know how to test that sensor on Jetta’s, but a Chilton’s or Haynes repair manual would probably have that procedure, among other sources like googling the internet. If you are having trouble with the testing, it might pay to have an inde shop with the VW scan tool check it for you, and then you can fix whatever’s broken yourself. Or take a gamble & just replace the sensor. Whether the voltages your are measuring are to spec or not depends on how the sensor circuit is designed, varies car to car.
Radiator fans of that era are often controlled by the engine computer reading the engine coolant temp sensor, and turning the fan on when the coolant reaches a certain temperature (around 200+ degrees F) via a radiator fan relay. If your car uses a temperature activated switch, which is surprising to me for a 2001, that’s like it works my early 90’s Corolla. I’ve had it fail two ways, the switch, and a broken wire between the fan relay and the fan. Replacing the radiator fan coolant temp switch was a reasonable thing, but if that didn’t fix it you’ll have to test at the relay next. Also, make sure what you are replacing is actually the radiator fan temperature switch. On my Corolla there are 5 different gadgets that screw into the water jacket, and only one of them is for the radiator fan.
Thank you for the reaponse. The trouble shooting when I measured the bolts across the first and third node with that on and then again with the voltmeter while hand turning the engine, we’re both from a Chilton book. The result of the first was odd because I got voltage while the car was off and the results of the second indicated that the sensor was fine.