No spark?

Tiny
TRUCKS69
  • MEMBER
  • 1999 JEEP CHEROKEE
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 126,549 MILES
Starts when cold then shuts off no spark what could the problem be
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Tuesday, October 12th, 2010 AT 10:35 AM

22 Replies

Tiny
JDL
  • EXPERT
Check for primary voltage at the coil. Dark green wire with orange tracer. Should be hot engine cranking. If no voltage check the fuses for the asd relay. Any applicable trouble codes?


https://www.2carpros.com/forum/automotive_pictures/170934_cherokee_asd_relay_1.jpg

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Tuesday, October 12th, 2010 AT 11:05 AM
Tiny
STELLA25
  • MEMBER
  • 1998 JEEP CHEROKEE
  • 4.0L
  • 6 CYL
  • 4WD
  • AUTOMATIC
Hi I have a 98 jeep cherokee sport I have no spark I have my self changed the cap rotor coil crankshaft p sensor turns over gets gas but no spark need help
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Monday, December 7th, 2020 AT 12:12 PM (Merged)
Tiny
CJ MEDEVAC
  • EXPERT
Check this guide out it can help us fix it.

https://www.2carpros.com/articles/how-to-test-an-ignition-system

Please run down this guide and report back.
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Monday, December 7th, 2020 AT 12:12 PM (Merged)
Tiny
STELLA25
  • MEMBER
No spark to the coil plugs nothing could it be the engine computer? Can I get the engine wiring diagrams please?
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Monday, December 7th, 2020 AT 12:12 PM (Merged)
Tiny
CJ MEDEVAC
  • EXPERT
Let's check out ez stuff 1st---then move on to the harder stuff

sending 3 diagrams----may be easier to print them and tape the corresponding wires together

start on page one---left side at top---"coil" (wire 1 [gray] and wire 2 dark green/ orange)

follow the positive wire---a highlighter will aid you---follow any "tees" the wire makes

trace them thru the diagrams---you will find that somewhere along the way ---"fuses" (maybe more than one)cool thing is "mitchell i" has them numbered! So you might go straight to the right one quick.

There maybe be relays too. They go bad. Sometimes as a test. You can swap it's identical twin (like from power windows etc) before you rush out and buy one, to see if that is the problem

"mitchell" also gives locations of components you come across

anywhere you find a "switch" along the positive wire----this could be a potential failure point. Like maybe the neutral safety switch, for instance. Anything could be broke/ become disconnected/ wire breaks

with a voltmeter or even a 12 volt test light. You can follow voltages to each "switch". Locate it coming and going at each component along the way. Remember that the switch/ relay must be "on" or "made" to trace voltages thru it

Check out the diagrams (Below). Please let us know what happens.
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Monday, December 7th, 2020 AT 12:12 PM (Merged)
Tiny
CONWILLI
  • MEMBER
  • 1998 JEEP CHEROKEE
  • 4.0L
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 155,000 MILES
I recently changed the motor mounts in my vehicle listed above XJ Limited. I had some trouble getting the motor back on the new mounts, but with some pulling, shaking, I was able to muscle and align it back into position. And when I went to start it it no longer starts. I have replaced the crankshaft position sensor and distributor so far. I tested for spark in which I have none at the ignition coil. At the ignition coil I tested the gray wire which is supposed to have constant 12v (when ignition is on) but there is nothing. When I crank the engine, I do get the required 12volts on the dark green/orange wire at the coil which leads me to believe there is no problem with the cam sensor, crank sensor, or automatic shutdown relay. My question is, how do I get the constant 12v power back? I traced the wire to the PCM computer. Possible problem with the ignition switch? Help!
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Monday, December 7th, 2020 AT 12:15 PM (Merged)
Tiny
ASEMASTER6371
  • EXPERT
Good morning,

The green/white wire is from the ignition switch. The gray wire should be hot through the coil. It is the coil driver for spark and does go to the PCM.

From your testing, it tells me the coil is the issue.

Roy
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Monday, December 7th, 2020 AT 12:15 PM (Merged)
Tiny
CONWILLI
  • MEMBER
Why would the coil be the issue if I don t have power to the coil through the gry wire to begin with? The 12v power power is a supply to the coil from the PCM, isn t that correct?
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Monday, December 7th, 2020 AT 12:15 PM (Merged)
Tiny
CONWILLI
  • MEMBER
What would cause the pcm to not send those 12v? Thanks
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Monday, December 7th, 2020 AT 12:15 PM (Merged)
Tiny
ASEMASTER6371
  • EXPERT
The PCM does not send power. It looks for the power from the coil. You are thinking backward.

You stated you have power to the positive side and that comes from the ignition switch.

That voltage should pass through the coil and go to the PCM which makes and breaks the ground for spark command.

Roy
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Monday, December 7th, 2020 AT 12:15 PM (Merged)
Tiny
CONWILLI
  • MEMBER
Thanks Roy you were right about the coil. I now have spark to the spark plugs. I wasn t able to get it started yet probably flooded it from cranking a bunch and dumping fuel in.
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Monday, December 7th, 2020 AT 12:15 PM (Merged)
Tiny
ASEMASTER6371
  • EXPERT
You are welcome.

Hold the gas pedal to the floor and crank it. That will clear the flooding and it should start.

Roy
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Monday, December 7th, 2020 AT 12:15 PM (Merged)
Tiny
CONWILLI
  • MEMBER
Roy,

Today I tried starting it again but it would not start. Confirmed again I have spark at all 6 spark plugs. When cranking, the air intake makes a gasp/gulping sound but sounds normal when depressing the gas pedal. I do have gas flow, can smell it. Any ideas?
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Monday, December 7th, 2020 AT 12:15 PM (Merged)
Tiny
CONWILLI
  • MEMBER
Backfires through intake.
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Monday, December 7th, 2020 AT 12:15 PM (Merged)
Tiny
ASEMASTER6371
  • EXPERT
Okay, I would check the compression to be sure it is not a timing issue.

https://www.2carpros.com/articles/how-to-test-engine-compression

Roy
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Monday, December 7th, 2020 AT 12:15 PM (Merged)
Tiny
JONATHAN HERRING
  • MEMBER
  • 1998 JEEP CHEROKEE
Computer problem
1998 Jeep Cherokee 6 cyl Two Wheel Drive

i replaced the computer on my jeep limited and it still as no fire going to my coil
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Monday, December 7th, 2020 AT 12:15 PM (Merged)
Tiny
JDL
  • EXPERT
Hello, can you check for codes? The ASD relay supplies primary voltage to the coil--injectors--heater circuits for the o2 sensors, I don't know what all.

The computer controls that relay on the ground circuit. A common reason for the computer not to ground that circuit, is because it doesn't see the proper cam and crank signals. I'm not telling you to replace anthing, you need to do some testing.
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Monday, December 7th, 2020 AT 12:15 PM (Merged)
Tiny
JONATHAN HERRING
  • MEMBER
Thanks I have been trying everything
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Monday, December 7th, 2020 AT 12:15 PM (Merged)
Tiny
TERRY BURCHFIELD
  • MEMBER
  • 1998 JEEP CHEROKEE
  • 4.0L
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 140,000 MILES
Coming home one night it just quit at an intersection.
It is not getting any spark. I have replaced the ignition module in the distributor, the coil, The sensor on the bell housing, and the PCM (main computer). I have checked the relays and still not spark. These were all parts that I was told to replace by a on line mechanic. This has cost me a bundle so far, but I am in too deep to quit. Car ran fine for the eight years I have had it only replaced a battery and AC unit in all that time and it is still in good shape. Am on social security so I cannot afford to take it to a shop.
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Monday, December 7th, 2020 AT 12:15 PM (Merged)
Tiny
DOCFIXIT
  • EXPERT
Try this, look at fuse box find automatic shut down relay remove find fuel pump relay remove and place in ASD slot. Then check for spark if there is replace ASD relay.
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Monday, December 7th, 2020 AT 12:15 PM (Merged)

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