QuestionTrying to get car to start. Checked sensors and relays. The fuel pump will kick on when we jump the wires in the relay. But still no spark. Would the PCM be causing this and is it located behind the battery?
Thank You,
Scott
AnswerHi Scott,
When you say you "checked the sensors" do you mean that you actually used a voltmeter to check that you were getting pulsing on the signal wire of each sensor, or that you just checked that the plugs and wires were OK? If only the latter, then you would either want to check for the voltage to oscillate on the tan/yellow wire of the cam sensor and on the light blue/dark blue of the crank sensor when you turn the engine over with a socket on the crank shaft pulley bolt, and the ignition switch 'on'. The voltage should oscillate between 5 and 0.3V compared to ground.
You can also check for fault codes using the ignition key: "on-off-on-off-on and leave on" doing this is 5 seconds or less elapsed time. Then watch the check engine light to begin to flash, pause, flash, etc. Count the number of flashes before each pause. The last two sets of flashes are always 5 in each. If you group the numbers in pairs in the order of appearance you get the two-digit fault codes. The last code number is 55 meaning end of readout. If you get an 11 code that is the crank sensor, and a 54 code that is the cam sensor.
The PCM is probably not causing this but rather one of the sensors not functioning. The box behind the battery to the left is the power distribution center. The PCM is located under the air filter/intake box on the right side front of the engine compartment, but it is probably not the issue.
Let me know what other codes you might get, and you can also go to www.allpar.com/fix/codes.html for a code translation.
The ASD relay is supposed to be closed for about 1 second when you turn the ignition switch to the run position, then because the engine isn't turning over it opens again. But during that second you should hear the fuel pump run and there should be 12V on the dark green/orange wire at the spark coil pack. Then when you start cranking the ASD relay closes again and continues closed as long as you are cranking or the engine starts and runs on its own. The presence of signals from the sensors is what tell the PCM to close the relay; if there is a missing signal then the relay will open as a safety precaution (turns off the gas and the spark). So that is why I ask about the signals both as a source of spark and fuel injection pulsing and as a cause for the relay to be closed.
Let me know what you find out, please.
Roland
