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Truck Repair/99 freightliner ecm


I am working on a 99 freightliner with an ISM engine. It will run for hours and sometimes days then die and not restart. I have pulled the harness for the ecm and ohmed and checked all the wires I can and can find nothing wrong. I have the following codes. Pid 168 with a flash code of 441 sid 232 and 251 with a flash code of 434. Can you offer any help. right now it wont fire at all. last time out it ran for five days before dying. Thank you.

Found that code 441 is unswitched battery supply circuit. So that will be the wire going directly from your battery to the ecm should be a fuse in it around the battery area.
Code 434 is the same code So definitely have something wrong in the battery power to the ecm. Never have worked on a ism in a freightliner but have worked on one in a international and if you follow the ecm power wires up to the ecm around the engine area was a weather pack connector and our international would do similar to what you have. it would run great for awhile the stop running what we found was that weather pack connector would lose contact so we would bypass it and solved all of our problems.

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Jeff Drumm


I Can answer any question pertaining to semi trucks and trailers. Have no experience in the automotive field so not able to help in that area.


My experiences in Semi Trucks is. I own my own truck and i presntly maintain a 80 truck fleet. Can handle any questions pertaining to a truck have tore apart and rebuilt every aspect on them. Fleet I deal with is Mainly Volvo trucks and a handful of freightliners. Work on automated transmissions on a daily basis along with carrier apu's. With engines my specialty is the 60 series Detroit but do work on the cummins isx the n-14 and the ism. and also the Volvo engines.

Have a College Degree from university of northwestern ohio in diesel and agriculture mechanics. Have 10 years behind the wheel driving a truck and 4 years working on trucks full time. Also have grown up on a farm so have been tinkering on trucks and tractors all my life.

Awards and Honors
I've gone through online schooling and have received certificates from webb wheel, Timken and Volvo academy.

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