QuestionI have a 95 LHS that cranks over but does not get spark at all cylinders and the spark it does get is weak. I have replaced the crank and cam position sensors and the coil pack and PCM and still no luck. Also, it is not throwing any codes. I have checked the coil pack connector for a pulse at the three wires going to the PCM and only one wire is pulsing correctly. One of them has steady voltage and the other is dead. I have voltage to the coil pack from the ASD relay and I have also checked the ground circuits to the PCM. I haven't checked the timing belt yet, I just assumed it would throw a code if it detected the cam out of position. Maybe you can point me in the right direction.
AnswerHi Bill,
It would be good to check the timing belt is still intact, but you are getting pulses on one wire from the PCM so it is probably ok. My inclination would be to verify that you have 8 volts on the orange wire at both the cam and crank sensors when your are cranking it. Then I would verify that the signal wires from the crank and cam sensor are continuous the PCM light blue/dark blue to pin 24, and tan/yellow to pin 44, respectively, and black/light blue ground wires both get to pin 4. You then could use a fine pin to probe through the insulation and then verify that the voltage on both sensor signal wires oscillates from 5.0 to 0.3 volts, 3 times, for each revolution of the engine when you turn it over by hand using a socket on the crank pulley. Those tests would assure that the pcm is getting the signals.
Then I would verify all 3 driver wires from the PCM to the coil: these come from pin 17, 18, 19 to the plug at the coil pack, even though you have verified the volages on two of them.
Thus if you are getting input signal to the PCM but not reliable pulses at the coil pack I would believe the PCM is not doing its job of driving the coil pack.
You have done the right tests so far, now just take it a step further.
Please let me know what you find out. Use the "rate the expert tab" to send me a "comment".
Roland
