Jim Chapman

My car has been having trouble. When I'm at highway speeds, the speedometer will either fluctuate or be flat at zero, while my RPM gauge will be high. Almost like it's not engaging overdrive. I've changed my VSS, vehicle speed sensor, and still nothing. Anything helps. Thanks

Olds64

Does the car drive normally even though the speedometer doesn't display?

Jim Chapman

No. It flutters a bit, and my RPM is at a 3 even if I'm doing 55-60mph.

Olds64

Being a 94 Oldsmobile it has a GM type 1 computer. Is there a check engine light?

You should be able to get the codes with the procedure I give in this thread (post #4).

https://classicoldsmobile.com/forums...mputer-123831/

Jim Chapman

No check engine light. But also, when in cruise control, it surges like it wants to accelerate instead of holding speed

Olds64

The cruise control servos for the GM cars in those years can be faulty. The 93 Buick LeSabre I owned that I mentioned in the linked thread had intermittent cruise issues. I disassembled and cleaned the servo multiple times. It helped the first time but the problem quickly reappeared.

Since I owned that car many years ago, I happened upon a Buick training video on YouTube that IDed the cruise problem as an internal part in the cruise servo that fails. Your best bet is to find a replacement in the salvage yard or live without cruise.

BTW, did you test for codes and didn't find any? If you disconnected the battery recently that would have cleared the memory of the computer.