1991 S10 Blazer 4.3L (Z) automatic, 4x4.

While driving at any given time the odometer mileage reading is replaced with "error". It will flash on and off sometimes or stay on for a while. Does not matter what the temperate is outside and doesn't seem to matter if it's raining out (higher moisture). SES codes are 33 (MAP) and 51 (MEMCAL or PROM). I have an all digital dash panel. :frown: Thanks

--raedeus

I am having a very similar problem with a 91 Sonoma 4.3, speedometer has filed completely but the odometer works fine. Did you get your problem resolved?

Thanks

Well, to my understanding if the odometer reads error occasionally it is either the PROM or MEMCAL chips on the computer. However, I couldn't find chip replacements so I bought a rebuilt computer from Autozone for $87.99. It comes in today so I'll let you know. I also checked my SES codes and pulled a code 51 off the truck which refers to "faulty PROM and/or MEMCAL" which refers to these ECM chips.