2002 3.7 Liberty no-start - JeepForum.com
 1Likes
Reply
 
LinkBack Thread Tools
post #1 of 21 Old 05-19-2020, 03:29 AM Thread Starter
stoneforge
Registered User
 
Join Date: May 2020
Posts: 14
2002 3.7 Liberty no-start

In the first week of the Coronavirus thing my 2002 Liberty (3.7 V6) dropped the intake valve seat on the #2 cylinder. After waiting through the shutdown I got a machine shop to do the work, then replaced the head "by the book". At this point the engine will crank just fine, but won't fire. It doesn't set any codes, so that's no help. I repaired a leaking injector and found an 02 sensor plug that wasn't seated correctly, so no problem with them. No 12 volt power to the center terminal at the coils, checked all the fuses involved, wiring wasn't disturbed other than to be moved out of the way. I'm stuck!

stoneforge is offline  
Sponsored Links
Advertisement
 
post #2 of 21 Old 05-19-2020, 04:12 AM
jtec
Web Wheeler
 
jtec's Avatar
2014 JK Wrangler 
 
Join Date: Oct 2017
Posts: 8,261
When turning key ON - does the CEL come on @ 3seconds then go off?

with key ON check for 12v at injectors and coils?
you are sure there is no 12v on DG/OR (green/orange) wire at coils?

ck PDC fuse #6, #24, and #26,
fuse box fuse #15

When I see the price of OEM I think aftermarket.
When I see the quality of aftermarket I think OEM.
jtec is offline  
post #3 of 21 Old 05-19-2020, 01:25 PM Thread Starter
stoneforge
Registered User
 
Join Date: May 2020
Posts: 14
jtec, when I got home from work I checked the stuff you sent...the CEL comes on but does not go out at all. No voltage at the coil plugs on either wire w/ ignition on. Checked fuses, all OK, also, no codes stored in the computer. I;ve been working on cars since 1960, and this one has got me beat! I'm grateful for any ideas you may have.
stoneforge is offline  
 
post #4 of 21 Old 05-25-2020, 12:51 PM Thread Starter
stoneforge
Registered User
 
Join Date: May 2020
Posts: 14
Latest developments in the continuing saga...at the urging of a friend I replaced the camshaft position sensor, but nothing changed. Still no power to the coils, CEL does not go out, no codes. I'm beginning to think the computer is mentally retarded.
stoneforge is offline  
post #5 of 21 Old 05-25-2020, 03:14 PM
jtec
Web Wheeler
 
jtec's Avatar
2014 JK Wrangler 
 
Join Date: Oct 2017
Posts: 8,261
if the CEL is on there is likely codes, maybe your scanner is not able to read all codes. SO what scanner are yu using to read codes? A code reader and a scanner are apples and oranges.

Lets cover all the what ifs - cheak the coil and injector voltage within 3seconds of turning key to ON/run position. A good easy 2 person check.
Brad426 likes this.

When I see the price of OEM I think aftermarket.
When I see the quality of aftermarket I think OEM.
jtec is offline  
post #6 of 21 Old 06-01-2020, 05:30 PM Thread Starter
stoneforge
Registered User
 
Join Date: May 2020
Posts: 14
Brad426, Sorry it took so long for me to answer, I drive a medical transport vehicle and things are nuts right now. Anyway, I have 2 code readers, the oldest one is 2005 and the new one is 2019 so it should be no problem for them both to read a 2002 vehicle code. Today I replaced the throttle position sensor because I saw some damage and even though it was working when the car broke down I thought it might be the problem, so I replaced it, no luck. Still no codes, CEL stays on, no power to the coil packs. It has become a test of wills, and right now the Liberty is winning. Anyone got any ideas?
stoneforge is offline  
post #7 of 21 Old 06-02-2020, 10:09 AM
Waterluvr
Registered User
 
Waterluvr's Avatar
2004 WJ 
 
Join Date: Apr 2018
Location: South Bend, IN
Posts: 384
Garage
So there's a few possibilities here, and I'll share a brief overview of what needs to happen in order to get those coils powered up to fire the ignition when the pcm drivers call for an ignition pulse to a specific coil circuit.

In a normal cycle when you turn the key and crank the engine the pcm supplies switched ground to the ASD relay in the pdc box, after initial start up when the skim module verifys the correct security code from the pcm it continues to switch closed ground to the ASD relay allowing the engine to run this powers up the hot side of both the coils and fuel injectors and the pcm switches coils and injectors on and off with driver circuits that open and close grounds to them.

In this case you need to see if the pcm is supplying a ground to the asd relay first, so go to the pcm and find the gray connector. There is a DB/YL wire that completes the circuit between cavity 3 on the pcm plug and the asd relay ground socket, turn the ignition to the on position and probe that wire to see if there is a ground being supplied by the pcm.
Waterluvr is offline  
post #8 of 21 Old 06-04-2020, 04:16 AM Thread Starter
stoneforge
Registered User
 
Join Date: May 2020
Posts: 14
I answered your note twice but neither one got posted so I'm hoping this one works. I found the DB/YL wire and probed it. The results were: with ignition off I got a ground, or at least it appeared as a ground on my meter, and with the ignition on it showed battery voltage. I think you're on the right track since no ground was provided as it should have been. What's next?
stoneforge is offline  
post #9 of 21 Old 06-04-2020, 09:33 AM
Waterluvr
Registered User
 
Waterluvr's Avatar
2004 WJ 
 
Join Date: Apr 2018
Location: South Bend, IN
Posts: 384
Garage
There should never be 12V on that circuit ever (pull the asd relay and see if that changes?) ~Also, unless the ignition is in the run position (key on engine off) you shouldn't have a ground.

If there's a ground with the key off the pcm is bad, and your asd relay will remain powered up all the time.
Waterluvr is offline  
post #10 of 21 Old 06-04-2020, 05:12 PM Thread Starter
stoneforge
Registered User
 
Join Date: May 2020
Posts: 14
I'll try pulling the ASD relay, but where do I find it?
stoneforge is offline  
post #11 of 21 Old 06-04-2020, 07:59 PM
Waterluvr
Registered User
 
Waterluvr's Avatar
2004 WJ 
 
Join Date: Apr 2018
Location: South Bend, IN
Posts: 384
Garage
Quote:
Originally Posted by stoneforge View Post
I'll try pulling the ASD relay, but where do I find it?
There's a spare right next to it if needed.

Waterluvr is offline  
post #12 of 21 Old 06-05-2020, 03:48 PM Thread Starter
stoneforge
Registered User
 
Join Date: May 2020
Posts: 14
I've got 3 days off so maybe I can make some progress on this car. Win, lose or draw, I do appreciate the help and the information...Thank you!
stoneforge is offline  
post #13 of 21 Old 06-06-2020, 08:04 AM Thread Starter
stoneforge
Registered User
 
Join Date: May 2020
Posts: 14
ASD...I pulled the ASD but no change. There was no spare relay, but the blower motor relay is the same one, so I swapped them but nothing changed. I got under the car and did a careful visual check of all the plugs and wires under there but all looks good. I know that a bad cam position sensor may cause a "no-start", so I have replaced the sensor, then today I probed the cam position sensor plug with the ignition switch on and got 5.4 VDC at the two outside terminals, nothing on the center one...possible clue? Also, the CEL stays on steady for about 10 seconds after turning on the ignition, then flashes for a few seconds, then back to steady on. According to the owner's manual that means that the OBD is not ready to work yet, and the cure is to start and run the engine. As old Willie Shakespeare said "therein lies the rub".
stoneforge is offline  
post #14 of 21 Old 06-06-2020, 09:00 AM
jtec
Web Wheeler
 
jtec's Avatar
2014 JK Wrangler 
 
Join Date: Oct 2017
Posts: 8,261
hope this helps... start with a test light .

NOTE circuit 'G' goes to the coils..
Attached Files
File Type: pdf 2002 ASD.pdf (151.4 KB, 6 views)
File Type: pdf 2002JeepKJ ASD S121.pdf (128.5 KB, 8 views)

When I see the price of OEM I think aftermarket.
When I see the quality of aftermarket I think OEM.
jtec is offline  
post #15 of 21 Old 06-07-2020, 09:35 AM Thread Starter
stoneforge
Registered User
 
Join Date: May 2020
Posts: 14
Today I used your diagrams and I think they were very helpful. Referring to diagram headed 8Wa-30-2-----8W30 FUEL/IGNITION SYSTEM------KJ, I tested components and everything is good at the ASD, 12VDC at terminals 86 and 30. Next in line is the PDC, fuse 26, and I have nothing on either terminal. In between is something labelled S121. Does your information tell what that is? Everything in the line from fuse 15 down to C1, pin 2 is good, and from PDC fuse 24 down to C1, pin 22 is good. This car originally came from Boston, which of course is coastal, lots of salt air and salt on the roads in winter, and I have had a ton of trouble with oxidized electrical connections and body rust. I know I'm spending way more than this car is worth, but we're trying to pay off some debts right now so I'd like to get it back on the road for awhile longer.
stoneforge is offline  
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.



Email Address:
OR

Log-in











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