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Truck will not start after replacing relay

Tiny
DAVIDRAMBO2
  • MEMBER
  • 2003 DODGE RAM
  • 4.7L
  • V8
  • 4WD
  • AUTOMATIC
  • 188,000 MILES
I was told I had a bad A/C condenser fan relay. So I bought one from AutoZone and replaced the bad one, but now my truck just cranks over and won’t start. I tried putting the old relay back in but no luck. Any help is appreciated.
Wednesday, August 21st, 2019 AT 3:06 PM

18 Replies

Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Good evening,

Check all your fuses with a test light for power on both sides. Do not do a visual test, do the power test.

https://www.2carpros.com/articles/how-a-car-fuse-works

Chances are you either have a bad relay or you put it in with the wrong terminal alignment and it shorted and blew a fuse.

Roy
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Wednesday, August 21st, 2019 AT 3:49 PM
Tiny
DAVIDRAMBO2
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I have tested all relays with a light, it couldn’t have been put in the wrong way, the pins were positioned to only fit one way.
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Wednesday, August 21st, 2019 AT 3:53 PM
Tiny
ASEMASTER6371
  • MECHANIC
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Did you test the fuses as I suggested? I asked for the fuses, not the relays.

Roy
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Wednesday, August 21st, 2019 AT 3:58 PM
Tiny
DAVIDRAMBO2
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Yes, sorry meant to type fuses and relays.
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Wednesday, August 21st, 2019 AT 5:01 PM
Tiny
ASEMASTER6371
  • MECHANIC
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What was the voltage at the fuses?

Roy
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Thursday, August 22nd, 2019 AT 2:14 AM
Tiny
DAVIDRAMBO2
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I tested them with a light like you said to. I have an ammeter but I am not sure how to use it to test the fuses.
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Thursday, August 22nd, 2019 AT 2:52 PM
Tiny
ASEMASTER6371
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Are these the 2 fuses you checked with a test light?

Roy
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Thursday, August 22nd, 2019 AT 3:01 PM
Tiny
DAVIDRAMBO2
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Yes, both of them light up.
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Thursday, August 22nd, 2019 AT 3:13 PM
Tiny
ASEMASTER6371
  • MECHANIC
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Can you check for spark? Crank the engine and see if the tachometer moves.

Do you hear the fuel pump run when you turn on the key?

Roy
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Thursday, August 22nd, 2019 AT 3:18 PM
Tiny
DAVIDRAMBO2
  • MEMBER
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Tachometer moves when I turn the key. I cannot hear the fuel pump priming.
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Thursday, August 22nd, 2019 AT 3:21 PM
Tiny
ASEMASTER6371
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Okay, the crank sensor is working.

If you have some starter fluid, spray it into the air filter and see if it starts and stalls.

Roy
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Thursday, August 22nd, 2019 AT 3:23 PM
Tiny
DAVIDRAMBO2
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Just to confirm, spray the fluid onto the filter itself?
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Thursday, August 22nd, 2019 AT 3:30 PM
Tiny
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Just squirt some fluid into the air filter.

Roy
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Thursday, August 22nd, 2019 AT 3:37 PM
Tiny
DAVIDRAMBO2
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Engine didn’t attempt to start, just cranking.
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Thursday, August 22nd, 2019 AT 3:39 PM
Tiny
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Can you check for any codes? Do you have something that can read codes?

Roy
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Thursday, August 22nd, 2019 AT 3:40 PM
Tiny
DAVIDRAMBO2
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I checked with my obd2 scanner, but it’s not throwing any codes.
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Thursday, August 22nd, 2019 AT 3:45 PM
Tiny
DAVIDRAMBO2
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This has me stumped. Thanks for continuing to reply quickly and consistently.
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Thursday, August 22nd, 2019 AT 3:46 PM
Tiny
ASEMASTER6371
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No worries.

Can you check for voltage to the coils? Do you have a voltmeter to check this?

I attached a diagram for you. Check the highlighted wires for power with the key on.

Roy
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Thursday, August 22nd, 2019 AT 3:51 PM

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