[thumbdoctor]

OBD I ground terminal "B" on the ALDL (assembly line diagnostic link) under the driver's side of the dash board. The check engine light will flash code 12 (ignition bypass) 1 long 2 short flashes in three sessions then immediately after that, the problem codes will flash in order of importance. Coolant sensor will be either a code 14 coolant sensor low (1 long 4 short) flashes or a code 15 coolant sensor high (1 long 5 short) flashes. For the cost of a coolant sensor, you might as well replace it as well as the thermostat (190 F).