Fixing lazy PCM. New caps writeup. - Page 2 - 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 > Fixing lazy PCM. New caps writeup.

December Specials at Jeephut.comROCK BOTTOM prices on LIFT KITS at Rockridge4wd!! WANT TO Alloy usa heavy duty ball joint kits

Reply
Unread 12-26-2009, 02:44 AM   #16
Bannonjr
Registered User
1993 ZJ 
 
Join Date: Dec 2008
Location: St Lazare
Posts: 390
wicked! Thanks for the pic...

better get of my arse and get this done.

__________________
Canada Synthetics.ca
Your Friendly Canadian Amsoil Dealer!


Red Jeep Club #151
Canadian Jeeps Club Member #25
Bannonjr is offline   Reply With Quote Quick reply to this message
Unread 12-26-2009, 04:16 AM   #17
ZJ5point2GCL
Registered User
1998 ZJ 
 
Join Date: Oct 2009
Location: Calgary
Posts: 3,392
so why would you do this? is it basically just for no-starts ?
ZJ5point2GCL is offline   Reply With Quote Quick reply to this message
Unread 12-26-2009, 10:29 AM   #18
AmbuGrl
Web Wheeler
 
AmbuGrl's Avatar
1998 XJ Cherokee 
 
Join Date: Oct 2009
Location: Virginia Beach, Va
Posts: 2,409
Quote:
Originally Posted by ZJ5point2GCL View Post
so why would you do this? is it basically just for no-starts ?
It is for more than no starts. Once you have troubleshot everything else and replaced what you need to replace and that doesnt work, this is another cheap fix to try. It will cost roughly $700 to replace a PCM with the dealer, it will cost less than $4 to fix it yourself with parts from radio shack. We had this issue (without knowing it) We replaced the fuel pump and filter, the ignition coil, the CPS, all of the relays and several fuses(roughly $600) before trying this fix. We found a few threads related to PCM probs before we found the fix from Gomes512. The probs described by others were indentical to ours. We had no CEL light at all, even after replacing the CPS. We figured why not and gave his write up a shot, she started right up and has been fine ever since.
__________________
- HM1(SW/AW)Ret USN Dec 23,1992 to Dec 31, 2012

I drive an XJ, and all of my power windows work :)



2000 Pontiac WS6 - DD
DD (Mine) Sold - 98 XJ Moss Green
(His) - 92 YJ December 2013 YJOTM

Sold - 95 ZJ
Sold - 97 XJ Red
Sold - 98 XJ


USN Jeep Club Hull #36
NAXJA #3700

Quote:
Originally Posted by RacerX View Post
WTF is Clockspring??? my Jeep has digital clock
AmbuGrl is offline   Reply With Quote Quick reply to this message
Unread 01-01-2010, 12:25 AM   #19
prplhz96
Registered User
2005 WK 
 
Join Date: Oct 2005
Posts: 18
Any more follow ups on this repair??? How long ago have some of you done this and still have no prior symptoms??? I am sure there are other things in the PCM that can fail, is there anything else I can replace while I am in there as more preventitive maintance?? Thanks in advance for any replies
prplhz96 is offline   Reply With Quote Quick reply to this message
Unread 01-14-2010, 05:55 PM   #20
gomes512
Registered User
1994 ZJ 
 
Join Date: Nov 2005
Location: Des Plaines, IL
Posts: 1,143
I did mine whenever the post was made. No problems, Jeep runs like a top.

The rest of the board should hold up through nuclear winter. I'm curious as to what's under that big 'ol heatsink. Obviously something that puts out heat, I could see that as being a future failure point.

The reason the caps are prone to failing is due to the harsh environment they are in. Constant heat/cool cycles are the problem. The caps in my vehicle information display on the other hand look great.
gomes512 is offline   Reply With Quote Quick reply to this message
Unread 01-17-2010, 04:57 PM   #21
kappa080
Registered User
1995 ZJ 
 
Join Date: Mar 2009
Location: Reno,nv
Posts: 12
The caps

Should the tops of the caps be blown at all? i really think that all my problems ive been having lately are thanks to the pcm but do not want to tear into the board if the caps arent going to fix it. thanks for the thread it helped alot.
kappa080 is offline   Reply With Quote Quick reply to this message
Unread 01-17-2010, 05:42 PM   #22
ZeeJay1997
Registered User
1997 ZJ 
 
Join Date: Dec 2008
Location: Sweet Home, Alabama
Posts: 6,879
delete a post???

Last edited by ZeeJay1997; 01-17-2010 at 06:12 PM.. Reason: deleted
ZeeJay1997 is online now   Reply With Quote Quick reply to this message
Unread 01-17-2010, 05:42 PM   #23
ZeeJay1997
Registered User
1997 ZJ 
 
Join Date: Dec 2008
Location: Sweet Home, Alabama
Posts: 6,879
Quote:
Originally Posted by gomes512 View Post
I'm curious as to what's under that big 'ol heatsink.
I'm guessing a voltage regulator for the 5V sensor output. All that extra voltage has to go somewhere.
ZeeJay1997 is online now   Reply With Quote Quick reply to this message
Unread 01-17-2010, 05:48 PM   #24
JrMechanic
Registered User
 
JrMechanic's Avatar
1993 ZJ 
 
Join Date: Oct 2008
Location: Lima, Ohio
Posts: 3,368
That looks familiar:

__________________
Want to swap an NP242 or NP231 into your ZJ? Here's how:
http://www.jeepforum.com/forum/f13/n...pdated-685644/
JrMechanic is offline   Reply With Quote Quick reply to this message
Unread 01-23-2010, 11:34 AM   #25
Garryjav
Registered User
 
Join Date: Nov 2004
Posts: 9
thanks for the write up, mine sat for a few months then would not start, messing with it a while it did start, thats when i noticed it would only start when the check engine light came on and found this post.
something that might help others is i only have a 140 watt soldering gun. it really was to big to get in to the small pins on the caps. what i did was to use a pc. of solid coopper wire 12 ga.i think it was and bend up a tip for my soldering gum out of the wire. it gets hot in a instant
Garryjav is offline   Reply With Quote Quick reply to this message
Unread 01-23-2010, 12:24 PM   #26
getoffmyland
Registered User
2007 JK Wrangler 
 
Join Date: Jan 2010
Location: uk
Posts: 84
the other reason for capacitors fail is due to a counterfeit operation that was / is running. Had a load of computer power supplies and motherboards fail due to capacitor fail. I would guess that the 12v to 5v circuit is failing because of the caps (they form part of a regulator circuit) and then whatever the PCM does is not working.
getoffmyland is offline   Reply With Quote Quick reply to this message
Unread 09-14-2010, 10:10 PM   #27
jeepjoe123
Registered User
 
Join Date: Sep 2010
Location: lake stevens
Posts: 1
Just to insert

Hey I have the same ecm problem on a 93 jeep grand cherokee. However I noticed that the part number from radioshack on here matched as a 85 C rating. The capacitors you remove from the ecm the 105 C ratings. I read up about that on this post

http://www.jeepforum.com/forum/f9/an...ir-pcm-628371/

That post said that radioshack didnt carry the 105 C rated ones. It does say you can get them from Digi-key. I checked with them and spoke with a tech and he said they did not carry the PL(W) series. He did say that these would be the same though

Digi-Key - 493-3277-ND (Manufacturer - UTT1E221MPD)

I posted because I saw everybody replacing theyres with the 85 C ones. Anyways thats my 2 cents worth after 3 days of thread combing. Props to all for the great info.
jeepjoe123 is offline   Reply With Quote Quick reply to this message
Unread 09-15-2010, 11:35 PM   #28
AUSjeepzj
Registered User
 
Join Date: Sep 2010
Location: Perth, PERTH ,WESTERN AUSTRALIA
Posts: 8
Gday I was just wondering if you are aware of the same problem with the PCMs on the 1996 models as Im having the same problem with my jeep, I have no power going to the coil and its been traced back to the PCM.
AUSjeepzj is offline   Reply With Quote Quick reply to this message
Unread 09-16-2010, 12:21 AM   #29
iPlay1515
Registered User
1993 ZJ 
 
Join Date: Jun 2006
Location: Southern Pines NC USA
Posts: 522
Quote:
Originally Posted by AUSjeepzj View Post
Gday I was just wondering if you are aware of the same problem with the PCMs on the 1996 models as Im having the same problem with my jeep, I have no power going to the coil and its been traced back to the PCM.
The PCM does not directly supply power to the coil. It supplies ground. However, the PCM does control the auto shutdown relay which in turn supplies power to the coil. Check the relay if you have no power on the coil.

You may have a fault that is keeping the PCM from closing the auto shutdown relay as it should.
iPlay1515 is offline   Reply With Quote Quick reply to this message
Unread 09-16-2010, 12:33 AM   #30
freakinheep89
Registered User
1995 ZJ 
 
Join Date: Jan 2010
Location: Mobile, Alabama
Posts: 3,252
Quote:
Originally Posted by iPlay1515 View Post
The PCM does not directly supply power to the coil. It supplies ground. However, the PCM does control the auto shutdown relay which in turn supplies power to the coil. Check the relay if you have no power on the coil.

You may have a fault that is keeping the PCM from closing the auto shutdown relay as it should.
also, a no power to coil is the main symptom of a CKS fault(crankshaft position sensor), have you eliminated that as an option?
__________________
TJ-
[SIZE="1"][B]95 ZJ 5.2[/B]- D30/XJ shafts/D35 Yukon alloys,249, 2"BB, 30x9.5"Wildcat EXT,lots of motor mods, rancho shocks & stabilizer.[/SIZE]

[QUOTE=slayercr23;12630497]How would i go about Stroking it?[/QUOTE]
freakinheep89 is offline   Reply With Quote Quick reply to this message
Reply

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the JeepForum.com forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid e-mail address for yourself.
Note: All free e-mails have been banned due to mis-use. (Yahoo, Gmail, Hotmail, etc.)
Don't have a non-free e-mail address? Click here for a solution: Manual Account Creation
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.


Thread Tools


Suggested Threads





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.