2002 Peterbilt C15 no crank, no start.

Discussion in 'Trucks [ Eighteen Wheelers ]' started by HillbillyDeluxeTruck, Jul 2, 2025.

  1. Ribeye

    Ribeye Light Load Member

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    Also I'd suggest check each battery for voltage, one could be crap. I've had that happen.
     
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  3. HillbillyDeluxeTruck

    HillbillyDeluxeTruck Road Train Member

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    Completely forgot to update this. Got the truck started with the jumper wire. Went ahead and dropped it to a mechanic I use last Thurs. with a new starter because we had 4th of July plans. He said he was going to double check my ignition switch before he put the starter in, which I didn't think about. I guess I'll know tomorrow.

    Those kinda got wiped out by all the rain and flooding here in the Tx hill country. My town was fine, the flooding just N of us was really, really bad.
     
  4. HillbillyDeluxeTruck

    HillbillyDeluxeTruck Road Train Member

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    Looks like its back to me diagnosing.

    Starter tests good, switch tests good. Next test will be to jumper the ign switch to verify.

    There is a large Bosch relay in the dash, mouted almost directly behind and above the steering column. It has a red/black wire with a tag that says "ign switch", along with a larger gauge orange wire. Can I assume that is the relay for the ignition?
     
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  5. HillbillyDeluxeTruck

    HillbillyDeluxeTruck Road Train Member

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    I am the biggest idiot on the planet...

    Of course there's a relay right on the firewall. Why would I even bother to look at that.
     
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  6. HillbillyDeluxeTruck

    HillbillyDeluxeTruck Road Train Member

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    Update, decided to swap the old worn out ignition switch and a new firewall relay with no change other than now getting an audible click from a relay somewhere in the dash or fuse block
     
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  7. HillbillyDeluxeTruck

    HillbillyDeluxeTruck Road Train Member

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    This is F'ed. I've traced out the wiring from the positive terminal on the starter where the small wire goes up to the connector, then to the relay on the firewall. Using a volt meter, I have power upto the connector that goes to the relay. Relay just clicks when turning the key or jumping power directly from the terminal to the start post on the back of the ignition switch.

    Now Im starting to suspect a ground wire issue.
     
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  8. beastr123

    beastr123 Road Train Member

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    Glad you and yours are safe and mostly dry
     
  9. D.Tibbitt

    D.Tibbitt Road Train Member

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    JolliRoger Thanks this.
  10. Goodysnap

    Goodysnap Road Train Member

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    The relay on the firewall is not needed with the relay on the starter your running. Just use one or the other but not both.
     
  11. Big Road Skateboard

    Big Road Skateboard Road Train Member

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    Agree with @Goodysnap, just run your signal to the firewall relay straight to the starter mounted relay. So bypass the firewall relay. If you're jumping it to that top signal, starter is good.

    If you're losing that signal when you load the circuit, check for a 5 pin relay for the starter signal. Not sure if they have one or not
     
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