Question For Experinced Ford Electrician!! - Ranger-Forums - The Ultimate Ford Ranger Resource


General Technical & Electrical General technical and electrical discussion for the Ford Ranger that does not fit in any other sub-forum.

Reply
 
LinkBack Thread Tools Search this Thread
  #1  
Old 03-30-2008
Member
Thread Starter
 
Join Date: Dec 2007
Location: moss,tn
Posts: 9
Question For Experinced Ford Electrician!!

Help much appreciated.. I have a 1993 FORD ranger 4.0 i am having a problem with coil pack blowing(i know it is blown cause when try to crank it ,it smokes and when i take it off there is a hole in coil pack) the wires are hooked up correctly. Have put three brand new ones on all do the same (getting expensive) The last one i put one it ran for at least 15 minutes then blew. I am not able to pull codes truck is undriveable witout coil pack working. Was wondering what to check please help i hate to see my FORD not on the road. I would rather not take it to a ford tech. any advice or knowledge about this situation will be appreciated!!
Reply With Quote
  #2  
Old 03-30-2008
67cobain94's Avatar
Member
 
Join Date: Jul 2005
Location: Vero Beach, Florida
Posts: 708
Well, you either have a bad PCM which is sending too much voltage to the coil, faulty wiring such as a short to ground in the coil wire circuit including a plug wire grounded to a piece of metal. Also, I'd pull the plugs and make sure none of them are broken. When the coil fires it's looking to have a certain amount of resistance in the ignition system and if it sees 0 resistance to ground it could very well be backfeeding and killing your coil. But I have seen a bad PCM do it the most. I make no promises without seeing the vehicle though, that's just my best idea of what to look for.
Reply With Quote
  #3  
Old 03-30-2008
Rev's Avatar
Rev Rev is offline
Level I Supporter
 
Join Date: May 2005
Location: San Diego, CA
Posts: 1,179
The only things that I can think of right off that could cause the coil pack to smoke would be:
1. A short in one of the three primary wires between the coil and the ignition control module.
2. A defective ignition control module.
3. An open circuit in the secondary (bad plug wire causing arc through internally in the coil secondary).
4. A defective coil pack (internally shorted primary).
Reply With Quote
  #4  
Old 03-30-2008
Level I Supporter
 
Join Date: Aug 2006
Location: Durham, NC
Posts: 3,657
Pull the primary connector off the coilpack (4 wire connector) With the ignition key on (run position), with your meter in voltage mode, meaure the
voltage on all 4 wires, one of them should be 12V. After finding the 12V terminal, but your meter in resistance (OHMS) mode, and measure the resistance on each of the other 3 wires. When you measure the resistance,
have your meter negative lead on GROUND. The coil drivers are open collector, and if they are ok, you should measure a high resistance.
Reply With Quote
  #5  
Old 04-05-2008
Member
Thread Starter
 
Join Date: Dec 2007
Location: moss,tn
Posts: 9
Quote:
Originally Posted by 67cobain94 View Post
Well, you either have a bad PCM which is sending too much voltage to the coil, faulty wiring such as a short to ground in the coil wire circuit including a plug wire grounded to a piece of metal. Also, I'd pull the plugs and make sure none of them are broken. When the coil fires it's looking to have a certain amount of resistance in the ignition system and if it sees 0 resistance to ground it could very well be backfeeding and killing your coil. But I have seen a bad PCM do it the most. I make no promises without seeing the vehicle though, that's just my best idea of what to look for.

First of all thanks for reply, where would the PCM be located on my ranger cause i have found the ignition module(EDIS) is that the same thing?? IN a manual i have it shows the PCM on the fire wall of the truck my 93 ranger or my 94 ranger neither one has this on the firwall where it shows it should be?
Reply With Quote
  #6  
Old 04-05-2008
Member
Thread Starter
 
Join Date: Dec 2007
Location: moss,tn
Posts: 9
Quote:
Originally Posted by Takeda View Post
Pull the primary connector off the coilpack (4 wire connector) With the ignition key on (run position), with your meter in voltage mode, meaure the
voltage on all 4 wires, one of them should be 12V. After finding the 12V terminal, but your meter in resistance (OHMS) mode, and measure the resistance on each of the other 3 wires. When you measure the resistance,
have your meter negative lead on GROUND. The coil drivers are open collector, and if they are ok, you should measure a high resistance.
I have cut the two power wires to the coil pack and put some fuses on them then tried out new coil pack and it still blew it . What size fuses would be the best to put in there?
Reply With Quote
  #7  
Old 04-05-2008
Level I Supporter
 
Join Date: Aug 2006
Location: Durham, NC
Posts: 3,657
Quote:
Originally Posted by 93blue View Post
I have cut the two power wires to the coil pack and put some fuses on them then tried out new coil pack and it still blew it . What size fuses would be the best to put in there?
Did you pull the primary connector and do the measurements I suggested?

And to John, the PCM DOES NOT provide voltage to the coilpack, it has open collector drivers that provide the GROUND path (pulsed) to the primary of the coil.
Now, if one of the drivers are shorted, this would create a high current condition.
Reply With Quote
  #8  
Old 04-05-2008
67cobain94's Avatar
Member
 
Join Date: Jul 2005
Location: Vero Beach, Florida
Posts: 708

Here is the wiring diagram for your coil. Voltage IS supplied to your coil from the PCM power relay, and the coils are grounded through your ignition control module. If the 12 volt feed is good, and your base ignition system is good, the best bet is to replace the Ignition Control Module.
Reply With Quote
  #9  
Old 04-05-2008
Level I Supporter
 
Join Date: Aug 2006
Location: Durham, NC
Posts: 3,657
Quote:
Originally Posted by 67cobain94 View Post

Here is the wiring diagram for your coil. Voltage IS supplied to your coil from the PCM power relay, and the coils are grounded through your ignition control module. If the 12 volt feed is good, and your base ignition system is good, the best bet is to replace the Ignition Control Module.
John, the PCM RELAY DOES NOT supply 12V to the coilpack!! 12V for the coilpack comes from the ignition switch, which also powers the coil to pick the PCM relay!!!!

Matter of fact, if you understood how a diode worked, you would see that the diode connected to the PCM relay in the schematic would be reverse biased to block
current flow from the PCM relay, but will pass current from the ignition switch into the PCM relay (coil).

Last edited by Takeda; 04-05-2008 at 06:17 PM.
Reply With Quote
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
Die-Hard Ford-ie, Ford-ite, Ford-iast ... cuddlepuppy59 Member Introductions 15 11-15-2013 02:42 PM
Ford Ranger - 1, Ford Flex - 0 NXD 5150 Snapshots 29 12-03-2008 04:58 PM
NOT a Ranger Light Question, but still a Ford Light Question buggman General Technical & Electrical 1 11-19-2008 12:00 PM
Bill Ford steps down as CEO of Ford Roach2004 General Ford Ranger Discussion 12 09-05-2006 11:40 PM
Ford or no Ford?? FX2.3 General Ford Ranger Discussion 13 09-04-2005 10:09 PM


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not 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 Off
Refbacks are Off



All times are GMT -6. The time now is 01:15 PM.


We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.