97 TJ ignition help

[ELindey]

Hello,

I am having a major issue with my 2.5l jeep that I have been trying to solve for about six months. Currently it cranks but will not start. The fuel pressure is good. I am not receiving any spark. We have traced it back to the power into the coil drops from 12 volts to .02 when it turns over.

I have replaced the timing sensors, the coil, the wires and plugs, the computer, the rotor and cap. The trouble shooting manual points to the computer being bad but replacing it didn’t change anything. Living in Germany getting parts is a little expensive and time consuming. My jeep is my daily driver and I really need to get her fixed.

I am also having a hard time finding a good wiring diagram for the early 97s. Thank you for any assistance,

Edward

 

[Paparock1]

https://wranglertjforum.com/threads...ice-manuals-fsm-technical-documentation.4618/
I know it seems weird but in your other post I mentioned checking and cleaning and lubing the ASD relay.

 

[ELindey]

https://wranglertjforum.com/threads...ice-manuals-fsm-technical-documentation.4618/
I know it seems weird but in your other post I mentioned checking and cleaning and lubing the ASD relay.

I replaced the relays. Also, I’m not sure what you mean by other post as this is my first post here.

 

[Chris]

I don't know much about the 2.5 engines as they are more uncommon, but did you replace the coil?

 

[Jerry Bransford]

Hello,

I am having a major issue with my 2.5l jeep that I have been trying to solve for about six months. Currently it cranks but will not start. The fuel pressure is good. I am not receiving any spark. We have traced it back to the power into the coil drops from 12 volts to .02 when it turns over.

I have replaced the timing sensors, the coil, the wires and plugs, the computer, the rotor and cap. The trouble shooting manual points to the computer being bad but replacing it didn’t change anything. Living in Germany getting parts is a little expensive and time consuming. My jeep is my daily driver and I really need to get her fixed.

I am also having a hard time finding a good wiring diagram for the early 97s. Thank you for any assistance,

Edward

This is out of the factory service manual. The top black lead provides 12v from the ASD relay to the coil. The bottom GY (gray) wire will have 12 volts on it as soon as the ignition is turned to start but it gets grounded (technically a pulsating ground) by the Powertrain Control Module (computer) while the engine is being cranked or while the engine is running. So if the gray wire is going from 12 volts to .02 while cranking, that is normal. Every time the computer grounds the gray wire, the coil produces a spark. It could look like a ground to any kind of a volt meter while the engine is being cranked or while it's starting.

Also, the 12 volts initially provided to the coil by the ASD relay will not stay on continually if the engine doesn't start. The ASD relay shuts it off if the engine doesn't start.

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[ELindey]

I don't know much about the 2.5 engines as they are more uncommon, but did you replace the coil?

Yes, coil replaced.

 

[Rubicon88]

Chrysler did some funky things over the years with security. Could yours be having a security/key type issue? Perhaps yours didn't have that feature. I don’t know the year by year doings of the security stuff by chrysler/jeep

 

[Rubicon88]

The computer. How do you know that's good? (The one you replaced it with)
The fuel lressure....what readings?

 

[Goatman]

JERRY does that say Generator field source on it? I thought that everything had switched to an alternator by the end of the 60's!
Sorry to derail. Also, why does the coil only have two wires? Or is this showing low voltage only?