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Unread 09-18-2013, 04:36 PM   #1
AnotherRedZj
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1997 ZJ 
 
Join Date: Feb 2012
Location: fort walton beach, fl
Posts: 1,631
While I was out wheeling a bit today it Jus shut down on me. Got it towed home and started messing with it. Seems its not getting spark.

I've been reading the "12 things....." Thread but am very a.d.d so I think alot got by me. First step seems to be right up my ally though. I tried to check for codes with the key and found that the CEL don't come on....at all. Not on startup or when I try for trouble codes. I know it used to work! I don't see it Jus burning out without coming on since last time. More importantly, there are no codes shown on the odometer. Not even a 12. This leades me to believe the pcm is dead. I tried wiggling it while cranking but no changes at all. So I hooked up my lil OBD2 scanner that works with my phone.....it tells me that it can not connected to the ecu.

I'm not very handy with a multi meter either so I'm not sure exactly how to check the coil or ckp. Also in my reading I came to check the wiring at the O2 sensor after the cat and found the harness to be partially melted to the exhaust. Got it disconnected but still no CEL.

I'm leaning towards the pcm, but I always think worst case, I've never had an issue with it at all so that puts me on the fence about it.

Should I even bother checking the ignition coil and ckp, if so what's the best way.

Any other input or insite would be greatly appreciated.

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Unread 09-18-2013, 04:51 PM   #2
ELMCZJ95
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Fuel pump maybe?
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Unread 09-18-2013, 04:57 PM   #3
AnotherRedZj
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Quote:
Originally Posted by ELMCZJ95 View Post
Fuel pump maybe?
sry a.d.d. got me again.

i tried priming the TB first before i F'd with any wires. no go.

thanx though
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Unread 09-18-2013, 05:57 PM   #4
Rich93ZJ
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Check the fuse for your pcm (under the hood #20 iirc). If it is blown, check your O2 sensor wiring for a short then replace the fuse. Good luck
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Unread 09-18-2013, 06:31 PM   #5
ZeeJay1997
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Quote:
Originally Posted by rich93zj View Post
check the fuse for your pcm (under the hood #20 iirc). If it is blown, check your o2 sensor wiring for a short then replace the fuse. Good luck
^^
this
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Unread 09-18-2013, 06:34 PM   #6
AnotherRedZj
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ill get on that after work tomorrow. right now is drink beer and forget about about my 2 outa 3 vehicles being down

keep the info coming though fellas! thanks
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Unread 09-18-2013, 09:55 PM   #7
stovie
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Had this problem before, turned out a wire to the tranny was rubbing on the shift linkage and blew a fuse. It should be a 20 amp one in your fuse box!!
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Unread 09-19-2013, 08:03 PM   #8
AnotherRedZj
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Checked fuses and relays all good.

Next question.....how exactly do you check if your pcm is in fact dead?
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Unread 09-19-2013, 08:09 PM   #9
ZeeJay1997
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Since the CEL is not coming on and you found mangled o2 wires, and you cant find a blown fuse, the PCM is a likely suspect.

before you condemn it, disconnect both os2 sensors and the crank sensor, turn on the key and see if you get the cel and key on back.

if not, it may be time to throw in the towel and get a pcm.
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Unread 09-19-2013, 08:11 PM   #10
AnotherRedZj
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Quote:
Originally Posted by ZeeJay1997 View Post
Since the CEL is not coming on and you found mangled o2 wires, and you cant find a blown fuse, the PCM is a likely suspect.

before you condemn it, disconnect both os2 sensors and the crank sensor, turn on the key and see if you get the cel and key on back.

if not, it may be time to throw in the towel and get a pcm.
I thought you would chime in here soon... You slowly becoming my hero!

.....and, will do. But I think I only remember there being one O2 sensor, that sound off to you?
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Unread 09-19-2013, 08:13 PM   #11
ZeeJay1997
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Quote:
Originally Posted by AnotherRedZj View Post
But I think I only remember there being one O2 sensor, that sound off to you?
one on the manifold and one on the cat.
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Unread 09-19-2013, 08:18 PM   #12
AnotherRedZj
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Quote:
Originally Posted by ZeeJay1997 View Post

one on the manifold and one on the cat.
Found it. But its not on the manifold, one before the cat and one after.
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Unread 09-19-2013, 08:24 PM   #13
ZeeJay1997
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ah, I'm stuck on 4.0s.

i dont know beans about a 5.2. i thought they had more than 2?
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Unread 09-19-2013, 08:32 PM   #14
AnotherRedZj
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Quote:
Originally Posted by ZeeJay1997 View Post
ah, I'm stuck on 4.0s.

i dont know beans about a 5.2. i thought they had more than 2?
Jus the 2.

Disconnected both and the ckp...no cel. And for good measure I tried the obdII scanner......it can find the "ecu" as It calls it, I know, its the same thing.
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Unread 09-19-2013, 08:46 PM   #15
ZeeJay1997
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it's the luck of the draw when the o2 wires get shorted. if the heater voltage shorts to ground it just blows a fuse. that is the best case, anything else can blow the internal circuits.
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