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Discussion Starter · #1 ·
So i picked up a 1998 TJ Sahara with the 4.0 and 5 speed manual (Ax15) transmission. The CEL is on and the code comes to a P0743 which is a TCC lock up circuit code. The trans is a 5-speed manual and can't figure out why this code appears. I've cleared the code, and it comes up right when the jeep is started.

The current owner has had the vehicle since 2001, and It doesn't look like the trans has ever been converted from auto to manual. The shift light turns on at higher rpm.

I've looked online (google and forums) and i have access to alldata and prodemand (which don't have very good info), and i cant figure this out for the life of me.

I know the wiring harness is the same for auto vs manual trans, but is there still a signal the PCM sends out through this circuit for a manual trans? There is a jumper in the connector at the trans where it would connect to for an auto trans, but am I missing something here? Has anybody run into this issue?

How can I tell if the pcm is the correct one?
 

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Sounds like you have a PCM from a vehicle with an auto

To see what your TJ originally get a free bold sheet for your vin from Chrysler
 

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P04886 689 is a PCM for a 1997 TJ built before July 24th with auto tranny

P04486 686 is a PCM for a 1997 TJ built before July 24th with 5spd

There in lies your problem
 

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Discussion Starter · #6 ·
Sonamabich!

Will a 97 6cyl manual pcm work in my 98 6cyl manual tj?
Is there a difference in pcm's between the 97 and 98 tj if they have same 6 cyl and manual trans?
 

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List of PCM part numbers for 4.0 TJ and XJ 97-04

1997 pre 7/24/97 TJ auto Fed 4886 689
1997 pre 7/24/97 TJ auto Calif 4886 689
1997 pre 7/24/97 TJ 5spd Fed 4886 686
1997 pre 7/24/97 TJ 5spd Calif 4886 686
1997 post 7/24/97 TJ auto Fed 56041 338AD
1997 post 7/2/974 TJ auto Calif 56041 338AD
1997 post 7/24/97 TJ 5spd Fed 56041 312AD
1997 post 7/2497 TJ 5spd Calif 56041 312AD
1997 XJ auto Fed 56041 277AD
1997 XJ auto Calif 56041 280AD
1997 XJ 5spd Fed 56041 274AD
1997 XJ 5spd Calif 56041 274AD
1998 TJ auto Fed 56041 627AE
1998 TJ auto Calif 56041 623AE
1998 TJ 5spd Fed 56041 617AE
1998 TJ 5spd Calif 56041 624AE
1998 XJ auto Fed 56041 534AB
1998 XJ auto Calif 56041 537AB
1998 XJ 5spd Fed 56041 531AB
1998 XJ 5spd Calif 56041 532AB
1999 TJ auto Fed 56041 469AC
1999 TJ auto Calif 56041 470AC
1999 TJ 5spd Fed 56041 465AC
1999 TJ 5spd Calif 56041 466AC
1999 XJ auto Fed 56041 492AC
1999 XJ auto Calif 56041 493AC
1999 XJ 5spd Fed 56041 488AC
1999 XJ 5spd Calif 56041 489AC
2000 TJ auto Fed 56041 657AC
2000 TJ auto Calif 56041 658AC
2000 TJ 5spd Fed 56041 652AC
2000 TJ 5spd Calif 56041 653AC
2000 XJ auto Fed 56041 634AE
2000 XJ auto Calif 56041 635AE
2000 XJ 5spd Fed 56041 667AE
2000 XJ 5spd Calif 56041 668AE
2001 TJ auto 50 state 56041 746AA
2001 TJ 5spd 50 state 56041 741AA
2001 XJ auto 50 state 56041 801AA
2001 XJ 5spd 50 state 56041 795AA
2002 TJ auto 50 state 56041 930AE
2002 TJ 5spd 50 state 56041 945AE
2003 TJ Not Rubi auto 50 state 56044 096AG
2003 TJ Not Rubi 5spd 50 state 56044 093AG
2003 TJ RUBI auto 50 state 56044 386AC
2003 TJ RUBI 5spd 50 state 56044 385AC
2004 TJ Not Rubi auto 50 state 56044 478AC
2004 TJ Not Rubi 5spd 50 state 56044 477AC
2004 TJ RUBI auto 50 state 56044 433AC
2004 TJ RUBI 5spd 50 state 56044 419AC
 

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As I understand the early 97 TJ is very different in sensor department and needs early 97 PCM


First I would try to fool PCM with a resistor on converter solenoid wire

It may fool it just seeing resistance or it may expect to see an RPM drop with lockup and if so the resistor may not fool it but early 97 not very advanced so my guess is a resistor will fool it and no more CEL or codes

Send in your in to Chrysler to see if originally auto with swapped tranny or a 5 SPd with swapped PCM
 

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Discussion Starter · #9 ·
What resistance does the pcm have to see in that two wire connector? The FSM, alldata and Prodemand don't list a diag tree to test resistance.
 

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Discussion Starter · #10 ·
What resistance does the pcm have to see in that two wire connector? The FSM, alldata and Prodemand don't list a diag tree to test resistance.
I found it! 30 ohms in a new tcc solenoid (found on this forum!)
 

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With alternator voltage at 14 volts or so that 30 ohm resistor will draw about one half an amp and generate somewhere around 7 watts so need a resistor rated for that and placed somewhere where getting warm is not an issue
 

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Don't remember it as a two wire I thought wire went from PCM pin to solenoid or resistor then to ground

So one side resistor to ground and other side to converter lockup wire from PCM

But double check as I am not a slush box guy
 

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Ok looks like it gets 12 volts with key on to one wire and PCM supplies a ground

So all you have to do is put resistor across those two wires

Or if you want to get fancy cut the other side of that connector off a tranny at you pull it and hook resistor to that cut off plug and then plug it in

Then either resistor will fool it or it will expect to see rpm change and still throw a code even after you clear the old one
 

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Discussion Starter · #15 ·
Had to put the cel repair on hold for the weekend due to a bad fuel pump right when i wanted to move the jeep back into the garage. But, I got the pump, got the resistor and will try to trick the pcm tonight!
 

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Discussion Starter · #17 ·
With a quick update: It's just one thing after another. So I replaced the fuel pump, and it wont start. This might not seems like a biggie, but au contraire.

-So, there is 47-49 psi at the rail, check with fuel psi gauge...
-There is power at the injectors because i tested them with a noid light
-There is spark between each spark plug AND the wire, BUT, when i pulled the spark plug out, it has a VERY faint spark. The plugs are wet which means it's getting fuel, but even though the spark plug tester shows there is a spark, could be a failing dist cap and rotor, and/or plugs. On my way to the store to get those and find out.
-It's not water in the fuel because i poured some from the rail into a metal cup and lit it on fire,aaaaaand it burnt itself dry.
-Compression is within spec.

Some background info i looked into: The crank pos snsr - this can't be bad because its giving a signal to the PCM to send a signal to the ignition coil and it shows a faint spark.

The only thing I ddnt check is timing, but the engine has only 87k miles on it, and this happened overnight.

We shall see!
 

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Timing not adjustable

Check engine ground from battery

Also verify good solid plus 12 to coil the PCM pulses the ground for the oil

Weak spark all wires
Coil or power or ground to coil
Or
Dist cap or rotor
Or
Engine block ground
Or
Primary wire coil to center of dist cap
 

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Discussion Starter · #19 ·
Found out what the issue was and got it started.

So, ass they always teach us, K.I.S.S (keep it simple stupid).

It was the Ignition coil. Turns out the coil was sending a weak spark that didn't ignite under compression. When testing it with the spark tester between the plug and wire, it showed a spark. What I took the plug out and grounded it, it still showed a spark, but a weak spark. So, i swapped ign coils with one I had laying around a VIOLA, she starts. I will start a new thread explaining testing procedures and what this means when you have different test results.
 

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Discussion Starter · #20 ·
Be interested to hear it it fools the PCM
So i placed a 30 ohm resistor into the harness where the harness would connect to the TCC solenoid for an auto trans, and CEL does not come on. Now, I only drove the jeep for about 20 mintues, but only got up to maybe 40 mph, so i don;t know what will happen at highway speeds, but for now, CEL is off with that resistor in place.
 
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