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Old 03-13-2010, 12:18 PM
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Join Date: Mar 2010
Posts: 37
engine swap, ecu died, can not start!

I recently bought a running(but knocking) 98 Sahara 4.0L 5 speed W AC. I found a 96 model 4.0L out of a wrecked cherokee AT. I went on a tangent to get this wrangler running. I pulled the engine out of the wreck and pulled it engine from the wrangler, then swapped all of the accessories, water pump and flywheel off of the 98. I had all this done and the engine in place to start in less than 24 hours.

I hit the key I had fire and I had fuel pressure to the fuel rail. I spun it over for about ten seconds and nothing would catch. I checked the timing again and realized I had it 180 out so I spun the distributor around, while I had the distributor out I changed it to the 96 distributor because the 98 distributor had a crack in the casing. After I changed the distributor it quit firing no fuel pressure nothing. I did accidentally spark the main hot wire going to the alternator, at the time I did not think it hurt anything. After about three days messing with it I realized the check engine light was not coming on when you turn the key on. I ordered a used 98 wrangler ecu, I put it in and everything came on, fuel pump, injectors are clicking and it is firing like hell but will not start. I have tried every fuse and relay. I have replaced the crankshaft position sensor, pickup in the distributor, coil, distributor cap rotor button. I have removed and cleaned or replaced all the ground on the engine to the frame and engine to firewall. I have cleaned the two ground going into the main harness under the hood.

Here is the kicker the only light that is on the dash is the no key light. Per the manual if it flashes it means it has the wrong key, mine is on SOLID. which in the manual says if the no key light is on constantly means it detects a wiring fault. I am to the point to take it to the dealership but I really hate doing that. It still works if I put the made NON smart key in it flashes. Has anyone had an other problems with a skim module going bad.

I have pulled it up the road to see if I can get it to fire but it just does not seem to want to. If you turn the key off and on it will fire for a second of two. Then it gives me the cod p1686 and p1391 p1686 means no skim bus module communication and p1391 mean occasional loss of distributor pickup. Both of these could be because I was dragging it up the road switching the key on and off, and the ecu was cutting power to certain things.

If you need more info let me know! If you have a guess, a crackpot scheme or an epiphany I will try it!

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Old 03-13-2010, 11:28 PM
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not even a nibble, someone told me some of the people on here eat sleep and drink thinking about the jeep wrangler, someone must have an inkling of an idea.

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Old 03-13-2010, 11:56 PM   #3
Join Date: Feb 2010
Location: Hemphill, Tx-Toledo Bend Lake
Posts: 115
I don't have a clue what might be wrong. I would take it to a local garage with a good reputation. Sometimes it's worth the money to have someone with experience figure it out. It's usually faster and might be cheaper. Good luck.
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Old 03-14-2010, 10:40 AM
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My father is a 30 year mechanic, I have worked on cars all of my life so I have a good ten years of experience. I just now believe it is solely in the pcm,ecu realm which neither of us have the equipment to deal with.
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Old 03-14-2010, 12:11 PM   #5
Join Date: Feb 2009
Location: Near Scranton, Pa
Posts: 97
Is the new ECU the same part number as the old one?
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Old 03-14-2010, 12:16 PM   #6
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Join Date: Jan 2009
Location: Wisconsin
Posts: 1,495
The weekend is not a good time to
get info here
Everyones out playing

I am sure someone will chime in

I am wondering if the computer for the auto
will work with the 5spd

"locked and loaded"
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Old 03-14-2010, 10:17 PM
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the computer is for the EXACT same thing 98 Sahara 5 Speed w AC 4.0L the numbers on the computers are the same 617AE if i remember correctly and T54061 orT54091 that is just off my head.
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Old 03-16-2010, 07:29 PM
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Ok I am still to annoyed to take it to the dealership so I went back and checked fuel and fire. It only fires the injectors the first time that you turn the key on so could it be something to do with the security/skim module.

Did they off a skim module on a 98 or is this something someone put on?

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