Two batteries so it has to be 24V right? Well that's what the guys in the yard thought. Lumberyard truck with a crane on the back. Engine started and ran after replacement of a relay. LUCK! Now the Instrument Cluster is dead. The warning lights illuminate and the gauges sweep at power on but otherwise nada. Using a Snappy scanner one time the BCM shows alive the next time dead. Huh, what? Fried instrument cluster? Start by diagnosing the BCM? Halp! I'm an auto electrical guy trying to help my heavy diesel buddy who's old school. Gimme anything Background // Research Found a schematic online. Hurrah! http://bodybuilder.navistar.com/General/Documents/svcmanpdf/s08315.pdf I found this thread on TruckersReport useful ' A .pdf on International's electrical system https://www.internationaltrucks.com...ctrical-Guide-Post-2007-HPV-Electrical-BB.pdf Ordered a service manual / wiring diagram off Ebay.
2 batteries does not equal 24 volt necessarily. heck most of my trucks have had 4 batteries, would that make it 48V? NO.. Series and parallel. Learn the difference.
My money is on some stuff got fried. Some manufacturers are even advising against jump starting these days due to voltage spikes taking out modules.
Lester, I'm an auto electrician attempting to diagnose & repair the damage, not one of the yard apes who incorrectly tried to jump start it.
I would start by disconnecting the batteries for a couple minutes. Re connect them and see what is working. What modules can you see with the scanner? There is a fuse box under the right side dash panel and there may be one under the hood Check all the fuses.
Best advice is check some fuses. All of them! Go along with a test light while ignition on and engine running and check for power on each side of each fuse, carefully note the ones that dont exhibit voltage on each end, then when done with the panel testing, go to a service manual listing for the fuses that didn't have voltage, identify the label, circuit they belong to and functions they would contribute to under certain circumstances. Then do your detective work to find out which one got ####ed.
