96 850 Turbo Wagon Cruise Control Surging Please Help

clarkr · Post by **clarkr** » 30 Jun 2025, 06:47

Hi all, having problems in cruise control mode.

1996 Volvo 850 Turbo Wagon - Automatic - Engine Type 57 - 2.3 L - 127,000 miles

Lately with Cruise Control I am getting an RPM surge between 300 and 500+ RPM at random times even when the CC switch is ON and NOT engaged. Getting surges when running under CC also. At a stop with foot on brake it sometimes surges like that and is quite frankly pretty scary.

This does NOT happen when I turn off the CC switch. Only when it is on. No surges with the CC switch in the off position.

Any idea's where to troubleshoot this? Any help would be greatly appreciated.

Thanks in advance,

Clark

clarkr · Post by **clarkr** » 14 Jul 2025, 08:51

UPDATE:

I replaced the Cruise Control relay with one I salvaged a few years ago. So FAR it seems to be working correctly now. Still more tests in the works but no surging so far.

Post by **scot850** » 15 Jul 2025, 12:03

The other option would be a vacuum leak to or at the pump possibly causing your issue. Hopefully all is now good.

Neil.