Are all PCMs bound to fail? - JeepForum.com
Search  
Sign Up   Today's Posts
User: Pass: Remember?
Advertise Here
Jeep Home Jeep Forum Jeep Classifieds Jeep Registry JeepSpace Jeep Reviews Jeep Gallery Jeep Clubs Jeep Groups Jeep Videos Jeep Events Jeep Articles
Go Back JeepForum.com > Models > Jeep Grand Cherokee & Commander Forums > ZJ Grand Cherokee Forum > Are all PCMs bound to fail?

FS: Jeep Fog Light LED Bulbs! Several Brightness Options! Stainless Steel Door Hinge PinsPoly Door Hinge Bushings

Reply
Unread 04-05-2013, 04:56 PM   #1
GRN74cj5
Registered User
1998 ZJ 
 
Join Date: Jul 2005
Posts: 33
Are all PCMs bound to fail?

I'm trying to do some preventative maintenance to the 127K mile 98 ZJ. We've had it 2 years now and the first thing to go was the radiator. With your help, I swapped it out for a CFS and I haven't had any issues. The fuel pump left my wife sitting, it was replaced and a few months later the check valve is letting fuel drain back into the tank. I have a bosch ready to replace it since we're tired of turning the key to on 3 times. I also have a new Mopar CPS ready to go in. I'm trying to address common problems before they occur and leave us sitting again. Lately I have been reading about the PCM issues many of you have had. I've been wondering if there is anything that can be done to prevent the known problem or is it age related? Mine is working fine (knock on wood). To me, that harness appears to put a lot of stress on the connectors, especially while on a bumpy road. There is a white colored tie that holds it to the firewall, but that appears to be it. Perhaps some large zip ties could be placed around the PCM to help stabilize things to limit shock to the connectors. I also wonder, are there ZJs that have really high miles and still have an original perfectly functional PCM? Maybe there were good ones and bad ones.

GRN74cj5 is offline   Reply With Quote
Unread 04-05-2013, 05:26 PM   #2
leadfootny
Registered User
1996 ZJ 
 
Join Date: Feb 2005
Location: Oswego, NY
Posts: 471
Most of the failing computers are of the 93-95 variety. The older models were susceptible to corrosion. Both of my zj's are on their original pcms with no problems (I should knock on wood). 256K on the 96 and 183K on the 98.
__________________
96 ZJ 4.0
98 ZJ 5.9
leadfootny is offline   Reply With Quote
Unread 04-05-2013, 05:40 PM   #3
ZeeJay1997
Registered User
1997 ZJ 
 
Join Date: Dec 2008
Location: Sweet Home, Alabama
Posts: 6,444
Be sure you don't have any exhaust leaks forward of the firewall. My theory is the extra heat has a detrimental effect on everything under the hood. No proof that this is the case, but it makes sense... to me anyhow...
ZeeJay1997 is offline   Reply With Quote
Unread 04-06-2013, 05:24 PM   #4
mholmes7979
Registered User
1994 ZJ 
 
Join Date: May 2012
Location: Spring, Texas
Posts: 39
PCM's are electronic devices and subject to failure due to heat but, don't fix it if it ain't broke. I have a 1994 and yes it broke.
mholmes7979 is offline   Reply With Quote
Unread 04-06-2013, 05:55 PM   #5
Exdecuk
Registered User
1998 ZJ 
 
Join Date: Dec 2011
Location: London, England
Posts: 410
I had a Mopar PCM in my 9er, parked it up for 2 years, went back to it and it was shot. Running the original again now till i get round to a Hemifever tune. The Mopar PCM had about 30K kilometers on it from new over about 6 years.
__________________
A man will pay $2 for a $1 item he needs.

A woman will pay $1 for a $2 item that she doesn't need but it's on sale.
Exdecuk is offline   Reply With Quote
Unread 04-06-2013, 06:29 PM   #6
jnowak
Registered User
1993 ZJ 
 
Join Date: Nov 2011
Location: dahlonega, ga
Posts: 469
93 with 289k knock on wood still going on original
jnowak is offline   Reply With Quote
Unread 04-07-2013, 01:17 AM   #7
cootertwo
Registered User
1997 XJ Cherokee 
 
Join Date: Jan 2012
Location: Labelle, Florida
Posts: 180
Like some have said, it's an electrical item. Some last, others don't. Like some televisions, some seem to go on forever, many die too soon.
cootertwo is offline   Reply With Quote
Unread 04-07-2013, 02:20 AM   #8
UAE59
Registered User
 
Join Date: Nov 2012
Location: Dubai, UAE
Posts: 12
most 97-01 cherokee PCM go bad faster than old models and they are easy to fix .. this what i saw
UAE59 is offline   Reply With Quote
Unread 04-07-2013, 05:06 AM   #9
ratmonkey
R.I.P.
 
ratmonkey's Avatar
1997 ZJ 
 
Join Date: Dec 2006
Location: , Pennsylvania
Posts: 19,795
Quote:
Originally Posted by GRN74cj5 View Post
I'm trying to do some preventative maintenance to the 127K mile 98 ZJ. We've had it 2 years now and the first thing to go was the radiator. With your help, I swapped it out for a CFS and I haven't had any issues. The fuel pump left my wife sitting, it was replaced and a few months later the check valve is letting fuel drain back into the tank. I have a bosch ready to replace it since we're tired of turning the key to on 3 times. I also have a new Mopar CPS ready to go in. I'm trying to address common problems before they occur and leave us sitting again. Lately I have been reading about the PCM issues many of you have had. I've been wondering if there is anything that can be done to prevent the known problem or is it age related? Mine is working fine (knock on wood). To me, that harness appears to put a lot of stress on the connectors, especially while on a bumpy road. There is a white colored tie that holds it to the firewall, but that appears to be it. Perhaps some large zip ties could be placed around the PCM to help stabilize things to limit shock to the connectors. I also wonder, are there ZJs that have really high miles and still have an original perfectly functional PCM? Maybe there were good ones and bad ones.
The zip ties are the previous owners attempt at fixing a bad connection that many 96-98 computers experience. You'll need to fix the solder joints or buy a new one sooner or later.
It's supposed to be bolted to the firewall with three torx head bolts.
Quote:
Originally Posted by Exdecuk View Post
I had a Mopar PCM in my 9er, parked it up for 2 years, went back to it and it was shot. Running the original again now till i get round to a Hemifever tune. The Mopar PCM had about 30K kilometers on it from new over about 6 years.
This is an extremely common failure method for dodge computers. So common in fact that many salvage yards wont sell them. They go bad just sitting around with no power.
Had you left a battery tender on it and started it once a month it wouldn't have gone bad.
__________________
'97 zj 5.2, some stuff, some other suff, and some things that even work sometimes.

ratmonkey is offline   Reply With Quote




Jeep, Wrangler, Cherokee, Grand Cherokee, and other models are copyrighted and trademarked to Jeep/Chrysler Corporation. JeepForum.com is not in any way associated with Jeep or the Chrysler Corp.