98 cherokee sport no spark
Alright gentlemen here is the latest. So parts replaced (all oem parts): plugs wires dizzy cap rotor ignition coil distributor ignition pickup and cps. Still no spark. Checked all fuses and qiring and nothing exposed or blown. Any ideas?
CF Veteran
Joined: Dec 2011
Posts: 1,050
Likes: 2
From: Roanoke, VA
Year: 1990
Model: Cherokee
Engine: 4.0
Do you hear the fuel pump prime when you turn the key? If not, for kicks and giggles, try jumpering the Asd relay. It eliminates it as an issue, or shows its faulty.
CF Veteran
Joined: Aug 2010
Posts: 8,357
Likes: 103
From: Canton, MI
Year: 1999
Model: Cherokee
Engine: 4.0
CF Veteran
Joined: Aug 2010
Posts: 8,357
Likes: 103
From: Canton, MI
Year: 1999
Model: Cherokee
Engine: 4.0
Did you perform the tests in my previous post?
In the previous post wiring diagram, did you notice that the coil is engine gounded. That is, the coil itself is grounded to the engine.
When you replaced the coil did you make sure the surfaces of the coil, and the coil mount, are clean and capable of grounding to the engine?
When you replaced the coil did you make sure the surfaces of the coil, and the coil mount, are clean and capable of grounding to the engine?
CF Veteran
Joined: Aug 2010
Posts: 8,357
Likes: 103
From: Canton, MI
Year: 1999
Model: Cherokee
Engine: 4.0
If you don't have voltage and/or ground pulse there may be a PCM driver problem or voltage supply problem. That is to say that the ASD relay is functional.
Last edited by CCKen; Oct 14, 2014 at 01:59 PM.
CF Veteran
Joined: Aug 2010
Posts: 8,357
Likes: 103
From: Canton, MI
Year: 1999
Model: Cherokee
Engine: 4.0
Yes it is a decimal 12 and yes im positive. I have 3.8 coming out the pcm but a quarter that actually gets to my ignition coil. I tried to take a picture but the downloader wouldn't let me
CF Veteran
Joined: Aug 2010
Posts: 8,357
Likes: 103
From: Canton, MI
Year: 1999
Model: Cherokee
Engine: 4.0
I think you should get another Voltmeter (Digital) and check your voltages again. Sometimes a bad Voltmeter will send you off chasing your tail with bogus readings.
Edit: The 12 volt power source to the coil does not come from the PCM. It comes from the ASD relay via fuse F21 in the PDC.
The PCM provides the ground driver for the coil.
The wire carrying the 12 volt source is the Dark Green.Orange tracer wire at the coil. The PCM driver wire is the Gray wire.
Last edited by CCKen; Oct 15, 2014 at 07:52 AM.
Volt meter is good. Even tested a few circuits on my wife's car and got exactly what it was supposed to be. So your telling me the dark green wire with the orange tracer coming from the pcm does not go to the coil. Tested it multiple times and every time it came back with the same reading
Last edited by old big red; Oct 15, 2014 at 08:37 AM.


