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Computer power issue

Tiny
JERRY BETZ
  • MEMBER
  • 2005 DODGE STRATUS
  • 2.4L
  • 4 CYL
  • FWD
  • AUTOMATIC
  • 128,000 MILES
Is there a fuse that I am missing for the power to the PCM? I have checked all fuses and all are good the car will not start and run at all but if I take out fan relay and run a positive power wire to the pcm terminal for the fan the car will then start and run. So is there a fuse that I am not finding that is bad?
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Saturday, December 31st, 2016 AT 7:23 PM

20 Replies

Tiny
STEVE W.
  • MECHANIC
  • 12,977 POSTS
Looking at the wiring diagram that back feed goes to a splice that leads to another splice that feeds the PCM. But because it runs with the feed in place I am thinking you have an issue right in the fuse box circuit board. The splices feed multiple areas as well as the PCM so if the splice was bad those would not operate even with the jumper in place.
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Saturday, December 31st, 2016 AT 10:00 PM
Tiny
JERRY BETZ
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  • 24 POSTS
Do not have fuel pump either before jumper or after jumper is in or at least I do not hear it running with jumper in. But it has to be running in order for car to run.
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Sunday, January 1st, 2017 AT 3:17 AM
Tiny
STEVE W.
  • MECHANIC
  • 12,977 POSTS
The splice is inside the PDC, it feeds the pump, PCM, Fan and a few others that all allow it to run. The jumper you add in bypasses the broken area and feeds the power "backwards" into the other side of the connection. So the pump and PCM get power.
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Sunday, January 1st, 2017 AT 3:33 AM
Tiny
JERRY BETZ
  • MEMBER
  • 24 POSTS
THE pdc doesn't have any circuitry board to it it's all wires going to each fuse and relay is there possibly a fusible link that is bad
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Tuesday, January 3rd, 2017 AT 7:46 PM
Tiny
STEVE W.
  • MECHANIC
  • 12,977 POSTS
No fusible links showing up except the one from the alternator to the battery.

I would check the connectors in the PDC, It shows fuse 14 as always hot PCM feed, to splice S104 inside the PDC and that feeds the PCM and the auto-shutdown relay.

Fuse 12 - low/high fan relay and A/C clutch.
Fuse 11 - switched power PCM fuse
Fuse 10 - ignition switch fuse that feeds fuse 11
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Tuesday, January 3rd, 2017 AT 9:37 PM
Tiny
JERRY BETZ
  • MEMBER
  • 24 POSTS
Steve do you have any diagrams that you could maybe send me or email to me to help me with this I notice tonight when trying to find the bad area that with jumper in place the service engine soon light will come on when key is on but will go out when jumper is removed
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Sunday, January 8th, 2017 AT 3:25 PM
Tiny
JERRY BETZ
  • MEMBER
  • 24 POSTS
I can't find any diagrams to help me with this
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Sunday, January 8th, 2017 AT 3:27 PM
Tiny
STEVE W.
  • MECHANIC
  • 12,977 POSTS
There are a couple places to get the diagrams, the better ones are on Mitchell. You could get a one month from http://www.eautorepair.net/Marketing/Default.asp
print out the wiring (there's like 15 pages on just power, grounds and data lines) so you can read them easier, for instance the power pages alone are 4 pages, print them and you can tape them together to trace the wires.
That way you have all the wiring available to you.
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Sunday, January 8th, 2017 AT 4:40 PM
Tiny
JERRY BETZ
  • MEMBER
  • 24 POSTS
OK thanks
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Sunday, January 8th, 2017 AT 7:19 PM
Tiny
JERRY BETZ
  • MEMBER
  • 24 POSTS
I can't sign up with them as I don't carry a credit or bank card is there any other sites that don't charge that I could use that is just as good
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Sunday, January 8th, 2017 AT 7:33 PM
Tiny
STEVE W.
  • MECHANIC
  • 12,977 POSTS
Not sure where you are but many libraries have access to the EBSCO system, that used to have a reasonable automotive area with schematics but I don't know what it looks like any more.
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Sunday, January 8th, 2017 AT 11:57 PM
Tiny
JERRY BETZ
  • MEMBER
  • 24 POSTS
I live in odon, Indiana
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Tuesday, January 10th, 2017 AT 1:36 PM
Tiny
JERRY BETZ
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Not quite sure what that is
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Tuesday, January 10th, 2017 AT 1:36 PM
Tiny
STEVE W.
  • MECHANIC
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EBSCO is an internet database. They have a ton of info and part of it is a link to auto repair information with schematics. I did find a different source for a manual if you're interested.
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Thursday, January 12th, 2017 AT 11:01 PM
Tiny
JERRY BETZ
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  • 24 POSTS
Yes what is it
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Friday, January 13th, 2017 AT 6:42 PM
Tiny
JERRY BETZ
  • MEMBER
  • 24 POSTS
Well Steve I'm stumped now if traced it down what my wiring diagram calls the mfi relay figured out that it doesn't have a ground so I gave it a ground and car will start and run but don't hear fuel pump after running for about two minutes it dies but starts back up but I can't figure it out cause when I was checking wires at pcm that wire was at the pcm and had a very low voltage reading of less than a tenth of a volt but at rely there was nothing but that reading comes out on positive instead of a negative do u have any ideas on how to fix this issue
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Tuesday, January 17th, 2017 AT 4:55 PM
Tiny
STEVE W.
  • MECHANIC
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That sounds like the driver in the PCM may have failed. That should be a pull down to turn the relay on.

What doesn't make sense is the running for a couple minutes. Unless the immobilizer is going flaky. That would give you the no start and no power to the MFI but it should show the security light (unless it's blown?) Or set off the alarm if that was the case.
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Wednesday, January 18th, 2017 AT 3:52 PM
Tiny
JERRY BETZ
  • MEMBER
  • 24 POSTS
OK I will have to check on the bulb and see if it is blown but I do have a brake light on and I've checked everything to do with the brakes and everything is working like it should and I don't believe it has abs because I can't find the abs pump anywhere so I believe that may be in the pcm as well and there isn't any Senor's for it either but then again it could just be a bad switch on e brake system
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Wednesday, January 18th, 2017 AT 7:26 PM
Tiny
JERRY BETZ
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  • 24 POSTS
Think I'm going to replace the pcm and see what happens but will check bulb first though before I replace it
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Wednesday, January 18th, 2017 AT 7:29 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
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Please let us know what happens so it will help others
Best, Ken
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Sunday, January 22nd, 2017 AT 2:50 AM

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