I have a 1993 gas 240 with 320k miles on the speedometer. When driving the ABS light flashes and the speedometer momentarily goes to zero.Other lights sometimes flash but ithappens so fast I can't always tell what's happening. Also the car engine appears to not run smoothly as this is going on. This happens intermittantly but more often than I like. I suspect it is the computer that either isn't seated properly or needs replacement. I am not a mechanic, however, I do the minor things associated with my Volvo's maintenance.

 

I would start with checking the charging system.

 

I want to let people know I found my problem. It was an intermittent battery chassis ground connection. The chassis ground connection along side the battery had corroded. I rerouted the connection to another location and several problems I have had with my Volvo have now been cleared up. The way I tested for the problem is to check for voltage between the battery negative terminal and the chassis (a good clean screw into the chassis metal). The voltage should be zero or nearly zero. I found some voltage indicating the negative battery terminal was not grounded properly to the chassis. You can do the same test to the motor block to test that the negative battery terminal is properly grounded to the engine block. These wonderful vehicles get old and have lots of miles that can cause strange thingsto happen - instrument lites flashing, etc. My first indication of trouble was my heater blower wouldn't work, then the AC, then later the instrument lites were flashing.

 

Thanks for the update!!!

 

I am new here. My daughter's 93 940 non-turbo sedan with 159K has a problem with the instrument warning lights. Would not come on when key turned before starting. Took it in last Friday and was told it was the ignition switch. $195 later still the same problem. Any suggestions?