EFI System Components


It is the larger of the sensors, Thermotime switch on the H2O inlet housing (brown in color, locaated below the water temp sensor that feeds the gauge in the car).
A 24mm socket is needed to remove it. The other swith is the H2O, locate beside the water temp gauge sensor. Check all of the connectors for corrosion. Do yourself a favor... get rid of the Haynes manual and buy a factory service manual. Dyment has them 1-800-247-5321.
To check the thermotime switch, unplug it, and remove the ground from battery.
measure the resistance between terminal no. 45 and switch body. If the ohmmeter sreding is between 51 to 62ohms, it is ok. If not, it is bad.
To check the water temp sensor, unhook the connector and check resistance before and after engine warm up. Place the meter probes on the two connector blades on the switch and check the ohm rating. Then check when the engine is warm. compare the following: (you will need a rod type thermometer, like one to test meats for cooking)
water temp resistance
C (F) ohms
-30 (-22) 20.0-33.0
-10 (14) 7.6-10.8
10 (50) 3.25-4.15
20 (68) 2.25-2.75
50 (122) 0.74-0.94
80 (176) 0.29-0.36


Water Temp SWITCH (has nothing to do with fuel injection circuit) Apparently in 49 state models, it advances timing and in Cali models, controls the completely useless EGR .