Help with 2002 DT466 code 525 - Diesel Truck Forum -
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post #1 of 3 (permalink) Old 07-04-2016, 04:31 AM Thread Starter
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Help with 2002 DT466 code 525

Hello all. I have a 2002 international 4300 DT466. Just purchased a few weeks ago, when purchased I suspected a few bad injectors, had 357,XXX on dash, had a miss, hard start w/knock when cold... Had injectors tested 5 out of six where bad.. So i replaced injectors with rebuilt/reman ones. Changed oil, oil filter, and fuel filter

After bleeding fuel system, truck started right up cold, but I noticed it still had a miss, upon trying to drive it, it lacked a lot of power very bad. At this point I didn't have a scanner to scan for codes.. truck continued to start for days, just no power, ordered scanner(nexiq) used servicemaxx to get codes, got dtc 525.. upon reading I noticed that rarely is the idm itself the issue, but normally a wiring/clean power issue.. I checked all the known issues, and noticed that all connectors and fuse holders had been changed or removed all together.. I did find bad battery in the process, and replaced. I have not been able to locate ecm relay. Is it in the fuse box? cec relay?

With KOEO standard test passes, injector test brings up dtc525, if I run that same test with injector harness unplugged at valve cover I get 513 and 514 as expected, but no 525. So my question is should I be looking at injector side of harness for problem, or is it still probably a power issue? When truck was starting I was able to verify that all 6 injectors were firing.. just wondering what I really should focus on? is it possible that IDM was really dying causing my misfire in the first place, and now its really dead and does need to be replaced?

my idm is integrated with em, if it is bad do they sell bottom boards for these models as well?
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post #2 of 3 (permalink) Old 07-04-2016, 05:36 PM
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Does this engine have the pass through connector on the side of the valve cover?


This is from the Navistar web site:

525 ECM Injector driver circuit DTC
ECM cannot supply sufficient voltage to injectors
Engine harness, injector harness or ECM problem
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post #3 of 3 (permalink) Old 07-04-2016, 08:04 PM Thread Starter
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Originally Posted by terry_g View Post
Does this engine have the pass through connector on the side of the valve cover?
yes it has circle connector for injector harness on side of valve cover
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