Throttle actuator re-install and ASR
Been discussing this one over in Hot-Rods; a couple of regulars have offered their assistance, but the problem isn't quite solved yet.
M119 V8, running perfectly, had the throttle actuator removed to inspect the integral wiring harness. Harness wires appeared to be in A-1 condition on inspection. Internals of TBA also in A-1 condition, no heat damage visible.
Replaced TBA-to-intake gasket and re-installed TBA. Left engine to sit for several minutes with ignition key turned and cluster lights lit, to allow computer to re-learn throttle stop location.
Engine starts instantly, but ASR light remains illuminated, and on test drive, limp-home mode is evident.
Checked diagnostic LED panel. A code 6 (idle speed control inop) is recorded. No other codes. Manually cleared code with the panel button.
Repeated startup procedure; identical symptoms presented (ASR illuminated, limp-home mode active, code 6 stored again).
Another member checked service order notes for his TBA re-install by a dealership tech. It said, quote, "... reset the Throttle Stop, Valves are OK. Cleared Faults. Runs to factory spec."
Two hypotheses here:
(a) the TBA is damaged despite looking good; should be replaced.
(b) the TBA is OK, but my re-install steps are flawed.
Assuming (b) for now. Which leads to three questions.
Is anything required to reset the throttle stop other than just to leave the key in the "on" position for a few minutes? Or does something get manually adjusted?
Is clearing codes from the diagnostic panel button OK, or am I going to have to perform a more specific procedure to reset the persistent ASR fault?
And what might the "valves" be in the service order notes? Only valve I know of in that area is the butterfly valve in the TBA itself, which is fine.
Grateful for any light anyone can shed; I'll write up this whole job as an article once it's finally finished...