[Gmecm] 92 riv help

[kctobyjoe1]

I went thru the HELM? 4" thick manual
It mentions'1' computer
Behind the glove box is an assembly that seems to be 2 computers wide
IF the BCM chip is bad is securing one difficult?
EVERYTHING works on my car but the odometer it SAYS ERROR
IF I change mileage type (E/M) works fine
switch from digital readout of speed to just bar works fine
runs great too
about 31 mpg after its major tune up 3 months ago

HELP!