The definitive factory manuals from Helm Inc. should have them, but of course they are over $100 unless you find a buy on Ebay. AlldataDIY.com is a convenient on-line way to get data that's more detailed than Chiltons. You can pay for a specific period or vehicle. Haven't checked prices lately because I invest in factory paper manuals whenever I adopt a new vehicle. The free ones available via a link here for download seem to include for the 2008 Isuzu Ascender, a sister truck, but most of the schematics are the same. Funny, I never looked at the 2008 one before.