No power to the coil

Tiny
MARC BOESLER
  • MEMBER
  • 1997 DODGE RAM
  • V8
  • 2WD
  • AUTOMATIC
1997 dodge ram 1500 Pulled out transmission and put back in, now wont start. No power going to engine fuse in console. Always started right up
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Wednesday, July 13th, 2011 AT 9:37 PM

6 Replies

Tiny
CARADIODOC
  • EXPERT
You have to check for voltage to the coil, any injector, or either small wire on the back of the alternator while the engine is cranking and for the first second after turning on the ignition switch.
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Thursday, July 14th, 2011 AT 12:27 AM
Tiny
MARC BOESLER
  • MEMBER
No voltage to the coil, injectors, or small wire in the back of alternator. What do I do next
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Monday, July 18th, 2011 AT 10:33 PM
Tiny
CARADIODOC
  • EXPERT
Was the voltage there for the first second after turning on the ignition switch? If it was, suspect the crankshaft position sensor. It should have been removed before the transmission was pulled out, and it requires a paper spacer to set the critical air gap when it's reinstalled.

If there is no voltage for that first second, there's an open fuse feeding the automatic shutdown (ASD) relay.
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Tuesday, July 19th, 2011 AT 12:44 AM
Tiny
MARC BOESLER
  • MEMBER
No power the first second but have power in two slots going to the ASD relay. Replaced ASD relay and still no power to the coil, injectors, and small wire to back of alternator.
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Tuesday, July 19th, 2011 AT 7:02 PM
Tiny
MARC BOESLER
  • MEMBER
Pulled off power distribution box under hood, using a test light I found I had no power leaving the ASD relay then using a test light I touched the blue yellow wire going to the power train control module, the ASD relay clicked. Using a multimeter, I found I had power coming out now. As soon as I took off test light, ASD clicked and lost power again. Could this be a bad ground or is the power train control module bad.
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Tuesday, July 19th, 2011 AT 10:08 PM
Tiny
CARADIODOC
  • EXPERT
Slow down; you're getting wrapped around the axle with misleading tests. Your test light grounded the coil of the ASD relay causing it to turn on. That's the job of the Engine Computer. Rather than tearing the Power Distribution Center which can be a pain to put back together, just measure that voltage at the coil or any injector, dark green / orange wire. That's the voltage that comes from the ASD relay when it turns on.

That relay turns on two different times. The first time is that one second when the ignition switch is turned on. It's very easy to miss it with a digital voltmeter because they often don't respond fast enough. A test light does a better job. Since you found voltage feeding the ASD relay contact and the coil, we know that part is okay. If you still don't find that voltage turning on for the first second, we have to determine if the relay is not being turned on by the computer or if the voltage isn't getting to the coil and injectors.

Use the test light to double-check that voltage at the coil. If it's not there for the first second, hold your finger on the ASD relay to feel if it clicks when a helper turns on the ignition switch. If it doesn't click, I suppose we could have a bad computer but that would really be rare. If it clicks but there is no voltage to the coil or injectors, look for a break in that dark green / orange wire.
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Wednesday, July 20th, 2011 AT 5:37 AM

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