Oh, but the rear stop lamps DO affect the cruise control! If the connection is dirty, it can prevent the CC from working -- the operating ground is through the lamp filament. Type of bulb, according to them, isn't significant, but I always use Osram on the advice of my professional mechanic friend. A bad bulb will also prevent the CC from working correctly, too, as well as lighting up the lamp out signal lamp. IF the current from the CC isn't sufficient to make a connection through a dirty bulb socket, no CC.

Surging isn't usually the amp, I don't think -- on 86-87 turbodiesels, it can be the air recirc valve on the turbo causing the surging -- there is a refit kit to smooth out the signal to the ALDA to prevent excessive power bursts. Mine did this before the tranducer died and I left it dead -- did fine on the flat, but would overrun the set speed on hills by 5-10 mph and osccillate down 5, up 4, down 4, etc until it stabilized. Annoying.

Otherwise, the usual suspect is dirty linkage, causing the actuator to stick. If this is the case, it will intermittantly disconnect when the actuator doesn't reach the correct posistion in time. Can be cured by cleanign the swivels in the linkage.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!