Diagnosing battery drain - JeepForum.com
LinkBack Thread Tools
post #1 of 3 Old 08-20-2013, 01:58 PM Thread Starter
Registered User
1996 ZJ 
Join Date: May 2012
Location: Diberville
Posts: 84
Diagnosing battery drain

I have been having intermittent stalling and no start problems, throwing codes 42 43(p0351) 72. The 72 low cat efficiency I have always had, the other 2 popped up recently.

I found out for sure problem is loss of spark. My battery was really, really dead. I got it charged to 12.4. With car running it goes to 13.78.

I'm a bit clueless as to how to diagnose battery drain. I have a voltmeter and continuity tester, but I'm not sure where to start.

I'm not good with electrical stuff. :/

1996 jeep grand cherokee laredo 2wd
240,xxx miles 4.0L i6
jeepgal2k12 is offline  
Sponsored Links
post #2 of 3 Old 08-20-2013, 02:47 PM
Registered User
2000 TJ Wrangler 
Join Date: Jul 2012
Location: 42.127628
Posts: 2,857
search the code numbers and then go from there as far as what they are...most have been covered somewhere on the site. Could also go to autozone or somewhere and have them read the codes to see what they are then start from there. I searched up 43 ignition control circuit not responding. I'm not good with electrical so someone else or maybe search around on that.

If i had to guess for a start. check all grounds and fuses and look from wires that are chewed, melted or stripped.

His:00 TJ "Fiona" stuff/stuff/stuff
95 ZJ 3.5" w/242 swap-Sold
Hers: 15 JK Sahara-3" Teraflex
tucsonzj is offline  
post #3 of 3 Old 08-20-2013, 07:35 PM
Registered User
1997 ZJ 
Join Date: Dec 2008
Posts: 9,000
Addressing the code 42, If your gas gauge works good, look in the PDC (fusebox under the hood) and find the fuel pump and ASD relays. Swap them out with the horn and intermittent wiper relays (if your horn and wiper are working good)

42* Auto Shutdown Relay Control Circuit
An open or shorted condition detected in the auto shutdown relay circuit.
42* Fuel Pump Relay Control Circuit
An open or shorted condition detected in the fuel pump relay control circuit.\
42* Fuel Level Sending Unit Volts Too Low
Open circuit between PCM and fuel gauge sending unit.
Fuel Level Sending Unit Volts Too High
Circuit shorted to voltage between PCM and fuel gauge sending unit.
Fuel Level Unit No Change Over Miles
No movement of fuel level sender detected.
* Check Engine Lamp (MIL) will not illuminate if this Diagnostic Trouble Code was recorded. Cycle Ignition key as described in manual and observe code flashed by Check Engine lamp.

For the P0351, this is sometimes a problem in the coil or PCM, but may be caused by bad grounds. Usually accompanied by a miss.
P0351 Ignition Coil #1 Primary Circuit
Peak primary circuit current not achieved with maximum dwell time.

This could be caused by a lazy rear o2 sensor or bad cat.
72** P0420 Catalytic Efficency Failure
Catalyst efficiency below required level.
** Check Engine Lamp (MIL) will illuminate during engine operation if this Diagnostic Trouble Code was recorded.

If you in fact have a parasitic drain, it's usually caused by something connected to the body control module, most notably a door module or switch. You need to be sure your charging system is up to par before you start chasing a drain.

Check out the links in my sig and read over everything.

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
ZeeJay1997 is offline  

Quick Reply

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:
Please enter a password for your user account. Note that passwords are case-sensitive.


Confirm Password:
Email Address
Please enter a valid e-mail address for yourself.

Email Address:


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.

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On

For the best viewing experience please update your browser to Google Chrome