 | |||||||||||||||||||||||||||||||||
|
|||||||||||||||||||||||||||||||||
|
Chrysler 2.0L & 2.4L Ignition SystemsPosted 5/10/1999By Greg Montero
The ignition system consists of a crankshaft position sensor, camshaft position sensor, PCM, ignition coil pack, plus the usual spark plug wires and plugs. The crankshaft position sensor is a three-wire hall-effect sensor that triggers off of a specially machined crankshaft counterweight. The counterweight has two sets of four notches machined onto it. The crankshaft position sensor is hardwired to the PCM. The PCM uses the sensor to calculate engine RPM, TDC No.1 and No.4, coil synchronization and cam-crank misalignment (for diagnostics). The 9-volt power supply from the PCM, 5-volt signal line from the PCM, and a sensor ground circuit all lead to the sensor. As the crankshaft rotates, the signal line voltage fluctuates between 5 volts and 0 volts. The way the camshaft position sensor works is similar to the crank sensor in that it is also a 3-wire hall-effect sensor, and is hardwired to the PCM. This gives the PCM cylinder identification, plus it is used for fuel-injector synchronization. A target magnet, attached to the end of the camshaft, has four different poles. As the camshaft rotates, so does the magnet. The cam sensor has identical electrical circuits going to it, just like the crank sensor, 9-volt power supply, 5-volt signal line, and sensor ground. As the cam (and magnet) rotate, the 5-volt signal line voltage fluctuates from 5 volts to 0 volts. Once the PCM has both sensor inputs, it can determine which coil to control and which injector to energize. The ignition coil pack has battery voltage supplied from the Auto Shutdown Relay. The PCM controls the saturation of the ignition coils. The two coils, built into a single housing, are serviced as an assembly. The PCM determines which coil to fire, based on the crankshaft/camshaft inputs. The PCM energizes the coil and at some point (timing) before the crankshaft sensor indicates TDC, it releases the ground from the coil to produce a spark. The timing is controlled 100 percent by the PCM and is not adjustable. Since the ignition coil primary winding has low resistance (.5 ohms), current flow is limited to about 8 amps. The current limiting function is provided by internal circuits inside the PCM. The coils are arranged with cylinders No.1 and No.4 on one coil, and No.2 and No.3 on the other coil. On most coils, the secondary resistance is 11.5K-13.5K. Output is around 40 KV per coil. To test the coil output, use two adjustable spark testers set to around 20KV each or about a 1/4 inch gap each. With both spark plug wires on the spark tester at the same time, there should be enough spark to jump the gap of both testers at the same time. Test the other coil pack the same way.
|
||||||||||||||||||||||||||||||||
Copyright (c) 1996-2008. Automotive Service Association. All rights reserved.
 | |||||||||||||||||||||||||||||||||
This information is provided by IDENTIFIX®. IDENTIFIX® resources cut diagnostic time and provide repair solutions that increase the shop's bottom line. From Repair-Trac pattern failure quick fixes, to Diagram-Online wiring diagrams by fax, to the Repair Hotline staffed by 32 master techs who specialize in diagnosing complex problems by phone or fax, IDENTIFIX® helps techicians fix more cars in less time.
