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Andy
Andy, Truck Diagnostic Technician
Category: Medium and Heavy Trucks
Satisfied Customers: 1675
Experience:  International and Isuzu trucks , International, Maxxforce, Cummins and Isuzu engines, Diagnostic and electrical troubleshooting specialist , Hvac and truck /trailer refrigeration troubleshooter
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I have a 01' Frieghtliner century S/T truck. The ground and

Customer Question

Hi. I have a 01' Frieghtliner century S/T truck. The ground and positive fuses by the batteries keep blowing
Submitted: 3 months ago.
Category: Medium and Heavy Trucks
Customer: replied 3 months ago.
It's a ISM Cummings. The truck will turn over but will not fire up!
Expert:  Andy replied 3 months ago.

Hi there . My name is ***** ***** Can we start with the engine serial number please ? It is an 8 digit number on the ecm or valve cover or front cover . Thanks

Customer: replied 3 months ago.
2PJ51984
Expert:  Andy replied 3 months ago.

Sorry . I am looking for an 8 digit engine serial number . It's all numbers

Customer: replied 3 months ago.
I'll have in a few hours. I'm not by the truck right now
Expert:  Andy replied 3 months ago.

It sounds to me like your ecm power feed is grounding out somewhere along the harness up to the ecm . That would cause these symptoms you are experiencing .

Customer: replied 3 months ago.
We traced the wires already for that. They were good. When you plug in the plug to the ecm. It burns the fuse instantly
Expert:  Andy replied 3 months ago.

Is your plug a 4 pin connector on the ecm ? Is that the plug that is blowing the fuse when you plug it in ?

Expert:  Andy replied 3 months ago.

Are you still there ?

Customer: replied 3 months ago.
I'm still at church.
Customer: replied 3 months ago.
I don't work on Sunday usually. I will get back to you this afternoon
Expert:  Andy replied 3 months ago.

Oh I see . Sorry about that !

Customer: replied 3 months ago.
Esn 35047916
Customer: replied 3 months ago.
I hope that's help you
Expert:  Andy replied 3 months ago.

Thanks .Is your plug a 4 pin connector on the ecm ? Is that the plug that is blowing the fuse when you plug it in ?

Customer: replied 3 months ago.
No, there is 25 pins on the plug
Expert:  Andy replied 3 months ago.

Here is your Ecm and connector locations

Expert:  Andy replied 3 months ago.

On the OEM port , you want to test and make sure you are getting unswitched power and ground at these pins :

Customer: replied 3 months ago.
What does unswitched power mean and how do I check it
Expert:  Andy replied 3 months ago.

It means battery power ( constant power from the battery ) . You would test by disconnecting the oem connector , finding those pin numbers and load testing them using a load light like a headlight , between a power pin and a ground pin to see if the wiring is good . Be sure to install new fuses before doing so , but disconnect the ecm oem connector first before doing so .

Customer: replied 3 months ago.
Ok thx
Expert:  Andy replied 3 months ago.

If you load test and light comes on bright , then circuit is able to carry a load just fine .

Customer: replied 3 months ago.
Ok. I won't be able to try the load until tomorrow. I'll let you know what I find
Expert:  Andy replied 3 months ago.

Ok sounds good . I work days so i'm mostly on in the evenings

Expert:  Andy replied 2 months ago.

Hi there ! Any luck with the load tests ?

Expert:  Andy replied 2 months ago.

Hi there . Just checking to see what you have found or if you need anymore help . Perhaps Skype would be a better option for us to diagnose this together.

Customer: replied 2 months ago.
We got the truck running but we put a hot wire from the battery to the injector pump to make a run
Expert:  Andy replied 2 months ago.

Ok so there is a problem in the harness somewhere by the sounds of it .

Customer: replied 2 months ago.
Can I run the truck like that will it hurt anything
Expert:  Andy replied 2 months ago.

I need to know exactly where you jumped to answer that . From battery positive to .... which pins ?

Customer: replied 2 months ago.
From the battery positive to the solenoid on injector pump
Expert:  Andy replied 2 months ago.

If that is the only thing you jumped , then perhaps there is a reason why the ECM is not powering up that solenoid . ( low coolant level , low oil pressure , high coolant temp) . One of these things may be off in readings

Expert:  Andy replied 2 months ago.

You are better to follow the information on theses two links to resolve your problem . I don't believe it is supposed to get a full 12 volts there .

Expert:  Andy replied 2 months ago.

Hi there . How's it going for you today sir ?

Expert:  Andy replied 2 months ago.

Hi there . Looking for an update on this ?

Expert:  Andy replied 2 months ago.

Have you been able to resolve the issue? Do you still need assistance or can I close this question ?