400E (124.034) V8-4.2L (119.975) (1992)
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Upshift Delay Control System
To heat up the catalytic converter faster, the no/partial load upshifts from 1st to 2nd and 2nd to 3rd gear in the automatic transmission are delayed. If the
engine coolant temperature is between 0 °C (32 °F) and 50 °C (122 °F), the LH control unit will delay the upshift to a maximum of 15 seconds after
engine start-up. The upshift occurs at higher RPM, accelerating catalytic converter warm-up.
The 1st to 2nd gear upshift delay is controlled by the LH control unit and the first gear start relay (K29/1).
The 2nd to 3rd gear upshift delay is controlled only by the LH control via the switch-over valve (Y3/3).
With the upshift delay switchover valve (Y3/3) energized, vacuum is applied to the control pressure cable vacuum element (8). This delays the gear
upshift point.
