k2keith

96 XJ 4.0 Auto w/ 270k, well used but loved nontheless

I am trying to get a good understanding of what exactly turning the key in the ignition does.

I know that it does the following -
1) unlocks the steering
2) If turned far enough it makes a connection to engage the starter

Beyond that does it simply turn on the electrical in the Jeep? Does it turn on all electrical at one time through 1 wire or multiple wires? How does it trigger fuel / spark functions?

Here is why I ask -
symptom 1) when I shut the ignition off the truck continues to run for another 5-10 seconds or so, not rough, coughing 'dieseling' as we used to call it, but steady strong, like the key had never been turned. Almost like the electrical was still powered up but the fuel supply was cut and the truck had to run until it ran out of fuel in the system.

symptom 2) a couple of times now, I have started it, it starts and runs fine (fine is relative with this many miles), however the lights, radio, wipers, vent fan, etc, do not work and the e-brake light remains lit (I don't have ANY guages (fuel, speed, odo, temp) at any time so I can't say what they are doing. I can drive it like this, later I will shut it off and restart it and everything is fine.

I am beginning to question if the act of me turning the ignition key is not triggering things to turn on/off as it should.

Any thoughts?
Keith

XJ Stryker

Go pick up a new ignition switch from auto Zone.

It is what the key ignition activates when turning the key.

Usually when you get problems like your stated the ignition switch is burnt up or degraded causing issues.

It is located on top of your steering column under the dash. Relativly easy to get to once you get under there and start looking. You may have to get the pigtail end of the harness too since they will get hot and melt.

RENIXBEAST

Sounds like a bad ground or loose connections. I would thoroughly check all connections and grounds.

fantic238

The ignition switch when i position ON, powers the latch relay that gives power to everything. After that, the ground of "everything" is provided by the computer.
When in START position, the switch powers the starter relay and starts the engine. What probably has been done (messed) to your electrical system, is a jumper wire somewhere to the harness that gives also a positive to the computer, but not to the fuel pump, this is why it continues running until the fuel pressure drops to 0. Check the wires for "strange" connections.

k2keith

thank you all for your responses, looks like I have some work ahead.

Keith

Bustedback

The switch is actually located right behind the key on the column. Remove the plastic covers and you will see it, black box looking thing with some white on it too. You have to remove the ignition cylinder from the switch by turning the key to the run position and pushing a pin on the bottom in, the cylinder should pull out with a little wiggling and tugging. Check the end of the ignition cylinder and make sure it is not chipped off. You may have to purchase a special torx driver for the tamper proof screws.