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Unread 07-20-2009, 07:56 PM   #1
dz1087
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Computers (ECU/PCM)

Hey guys. I've got a friend with a 98 grand, 6cyl, auto(not sure which one) that is needing a replacement computer, or at least thinks he does. What years would be compatible for him? To be honest, I can't even remember when the ZJ went to WJ as I'm kinda a noob in the grand world.

He says he has replaced the CPS, distributor pickup, coil, and cap and rotor, and still no spark on his engine. Said sometimes it would take a while to crank, then worked for a few days and then completely quit. All help appreciated.

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Unread 07-20-2009, 08:03 PM   #2
ZeeJay1997
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Thats going to be a PCM for a 98.

There's a standard Mopar replacement but it has to be installed be the dealer to load the proper software for make/model (flashed). I think i read where this runs about 600-800 bucks

There are remans from several online suppliers who will send it to you flashed for about 200 bucks.

I opted to get the part number off the bad one and get one from a salvage yard for 150.

So, you have options!
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Unread 07-20-2009, 08:07 PM   #3
Virmagicus
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I am not convinced that the ECU is bad. Has he tried a new TPS ?
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Unread 07-20-2009, 08:08 PM   #4
dz1087
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Not sure about the TPS.
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Unread 07-20-2009, 08:12 PM   #5
ZeeJay1997
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Try swapping the ASD relay in the fuse box under the hood with another one. They are all the same.

The TPS wont keep it from firing
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Unread 07-20-2009, 08:12 PM   #6
Virmagicus
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Quote:
Originally Posted by dz1087 View Post
Not sure about the TPS.
Could be the TPS. A bad ASD relay will also cause a no spark issue but you did mention that it would start after awhile. Try swapping with another matching one in the PDC.
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Unread 07-20-2009, 08:41 PM   #7
dz1087
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Right now it is n start period, but this is after hard starting for a period of weeks.
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Unread 07-20-2009, 10:04 PM   #8
gomes512
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b4 replacing comp check the capacitors on the circuit board to ensure they did not rupture.
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Unread 07-21-2009, 12:23 AM   #9
ratmonkey
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98 pcm only, and he needs his vin programmed into it or the sentry system will shut it off after 3s of running.

I vote for asd as well.
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Unread 07-21-2009, 03:36 AM   #10
ZeeJay1997
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b4 replacing comp check the capacitors on the circuit board to ensure they did not rupture.
Not a good idea on the 97-98 having the JTEC PCM. The PCM that the capacitors can be replaced on is on the SBEC that came on earlier models. The difference is the pliability of the conformal coating and the JTEC has micro circuits as opposed to wire lead semiconductors.

If there's not actually a problem in there, you'll do more harm than good.
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Unread 07-21-2009, 10:36 AM   #11
dz1087
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I'll have him check the ASD relay. Don't know if it's a sentry Jeep or not.
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http://www.jeepforum.com/forum/showthread.php?t=565361

There can be no fifty-fifty Americanism in this country. There is room here for only 100% Americanism, only for those who are Americans and nothing else.
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Unread 07-21-2009, 01:07 PM   #12
ratmonkey
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Quote:
Originally Posted by dz1087 View Post
I'll have him check the ASD relay. Don't know if it's a sentry Jeep or not.
the security system is standard on all grand cherokees, if your vin doesn't match between the bcm and pcm in a 98 plus, it will not run for more than 3 seconds.
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Unread 07-21-2009, 02:33 PM   #13
gomes512
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Quote:
Originally Posted by ZeeJay1997 View Post
Not a good idea on the 97-98 having the JTEC PCM. The PCM that the capacitors can be replaced on is on the SBEC that came on earlier models. The difference is the pliability of the conformal coating and the JTEC has micro circuits as opposed to wire lead semiconductors.

If there's not actually a problem in there, you'll do more harm than good.

Good to know, thanks for the info!
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Unread 07-21-2009, 02:47 PM   #14
TX-WJ
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Make sure he checks all the fuses on the junction block and the power distribution center (engine compartment) before getting a new PCM.
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