I am searching through misc. codes myself and I happen to come across this code. Apparently there are ECM Quad Drivers 1 thru 4. Driver 1 sends commands to the EGR. It is not Isuzu specific, but the codes appear to be pretty generic and apply to OBD II. And I know it's pretty vague, but I hope it helps.
EDIT***
Strike all that bullhockey above. It is too generic. But then Isuzus definition is even more crap. A P1640 code is just an improper voltage was detected on an output driver module. But doesn't say which One. It will clear itself after 40 consecutive warm up cycles without another fault. They go on to say to check for a poor connection at the ECM, a damaged PCM harness, or a poor connection at the insrrument cluster, canister purge solenoid, A/C clutch relay. Sounds like they're gonna have your running in circles! Anyway, it's a start.
Last edited by AnalogVX : 01/12/2006 at 03:11 PM
RichD
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