YJ No Spark

Nope, the CPS doesn't have any current flowing through it unless the engine is running... and then that current is self-generated. :)

Jerry

Dave Lee wrote:

Dave Lee did pass the time by typing:

Start simple.

Spark from the coil? Hold the coil lead by the block and see if it draws a spark when you turn the engine.

Double check you put the rotor in there. :) And the camshaft position sensor pickup on the distributor is hooked back up.

And the plugs are going to the proper post.

With a bad timing chain, it's still gonna spark - just not where it should. Crank Position Sensor would be #1 suspect, Cam Position Sensor (inside the distributor) is a possibility as is a bad coil - but the Crank sensor is more common.

Dave Lee did pass the time by typing:

Your seeing the solinoid close, it's basically a big ass relay and will spark.

Could be the coil. but before going there, double check the harnesses around where you were working. Sometimes things come loose.

You can take a noid light (12V lamp) or multimeter and measure across the coil primary (small side) while starting the engine. You should see 12V pulses If you do then the coil is shot.

The crank sensor operates on voltage that is supplied by the PCM anytime the key is on, running or not, and does not generate current.

Then tell us all what a reluctance head pickup is, because that is exactly what the CPS is.. :)

Jerry

bllsht wrote:

Hmmm.....

Normally I would say the bad connection sparking down at the starter would be the power 'not' going to the ignition module via the bypass when the starter is cranking. The power goes direct to the module when the key is in run.

Though I didn't think the solenoid had those connections on it at the starter, I thought those connections were on the relay on the firewall. They are on most of the 6 bangers anyway....

The other thing that can spark at the starter is the main wire being loose. This can cause a major amp draw when the starter is turning. Enough draw that maybe enough isn't left over to turn on electronics. If the power goes too low, some things just won't turn on.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's

Dave Lee wrote:

Exactly wrong...

The crank sensor used on a 95 YJ is a hall effect device. It's a 3 wire sensor. The PCM (SBEC) supplies the ground, 8 volts to operate the circuitry in the sensor, and a 5 volt reference(signal circuit). These voltages are present any time the key is on.

The sensor alternates between pulling the reference voltage to ground (zero volts), and releasing (5 volts), depending on whether it's aligned with a "gap" or a "tooth".

Put a lab scope on the signal circuit and you'll see a 5 volt square wave. No current is generated by the sensor.

I don't know what you're thinking of but it's not a 95 Jeep.

I'll be darned, I had been thinking it was a reluctance head pickup all these years, a device I'm very familiar with. I've used them in similar circuits to generate timing pulses just like this particular circuit. Thanks!

Jerry

bllsht wrote:

Nope, a Hall Effect device doesn't draw even close to that much current.

Jerry

Dave Lee wrote: