PO357.& Voltage drop issues under load

Tiny
MIKEMUKA
  • MEMBER
  • 2003 DODGE RAM
  • 113,000 MILES
My problems began when I jumped a buddies e350Ford when cables were still attached he started his truck revving his motor and my volt meter went crazy.I jumped out and disconnected jumper cables. Within a week alternator went bad.I replaced alternator and battery and the truck has never been the same.I am original owner the volt gauge has always been above half to half under full load(air cond. Ligjts. Etc).I have since replaced alternator agin and same results. Dashbiard lights dim. All lights dim and volt gauge is way below half at full stop. Then accelerate and comes back to half on gauge and everything brightens again.I have had battery and alternator tested. They tell me they are good.I understand their is an internal pcm regulator. Not sure how to test. Now new issue. Slight rough idle and pcm code 357. Votage probem coil #7.I ohm meter tested the coil with a couple of the other coils and seem to get same reading so I don't think its the coil. Bad pcm. Please help. Thank 2003 dodge ram 1500 5.7 hemi 4x4.
Thursday, May 9th, 2013 AT 10:19 AM

3 Replies

Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
For the alternator check the fusible link and fuse where pointed out in pic. One may have blown internal regulators when an alternator is tested means they are ok too. By chance the blown fuse or link may fix both your problems buti'm sending two pics along on how to test for 357.
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Thursday, May 9th, 2013 AT 12:36 PM
Tiny
MIKEMUKA
  • MEMBER
  • 4 POSTS
Thanks for quick response.I really appreciate your help. Fuses all check fine. How do I know fuseible link is bad.I have 12 volts at alternator with truck off. Doesn't that elimate link? Or is there something I am missing. Thanks I really miss my truck.I will check coil tomorrow thanks for schematics. Got off work late.
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Thursday, May 9th, 2013 AT 4:52 PM
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
You should have the same voltage at blk/gray wire at fuse 19 an fusible link on alternator end. If that's ok then it will have to be scanned to try to find problem. It may be a module. Also check your grunds for cleanliness they are shown in drawing.
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Friday, May 10th, 2013 AT 5:47 AM

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