Hi HEF! re: CAT 420D TLB Serial Number Suffix FDP 08XXX As the subject line explains, we're hunting for a Service Manual for a CAT 420D Serial Suffix FDP7199-Up. This machine no longer shifts into reverse; hence, the need for a powertrain manual. The audible reverse alarm comes on when the shuttle shift lever is shifted into Reverse. Also, both the hydraulic shift solenoids/relays have either been swapped or, in the case of the reverse solenoid, replaced with a new unit. Regardless, there is 12VDC present at both solenoids when shuttle shifts are made. At one point, I removed the transmission filter screen and found a small amount of rubbery debris trapped in the filter. The transmission fluid in the English transmission was subsequently replaced with the appropriate amount new CAT transmission fluid. A pressure test has NOT been performed, but all indications are that there is an internal problem in our CAT 420D's transmission. By the way, this problem used to be intermittent, but it now seems to be permanent. Any thoughts about this will be well received!
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